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A comparison of facial injury management undertaken at US and UK Medical Treatment Facilities during the Iraq and Afghanistan conflicts ForJournal: peerBMJ Open review only Manuscript ID bmjopen-2019-033557

Article Type: Original research

Date Submitted by the 13-Aug-2019 Author:

Complete List of Authors: Breeze, John; Royal Centre for Defence Medicine, Royal Centre for Defence Medicine Bowley, Douglas; University Hospitals Birmingham NHS Foundation Trust Combes, James; Royal Surrey County Hospital NHS Foundation Trust Baden, James; University Hospitals Birmingham NHS Foundation Trust Rickard, Rory; Royal Centre for Defence Medicine DuBose, Joseph; R Adams Cowley Shock Trauma Center Powers, David; Duke University Medical Center

Military, Face, Trauma management < ORTHOPAEDIC & TRAUMA Keywords: SURGERY

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1 2 A comparison of facial injury management undertaken at US and UK 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Medical Treatment Facilities during the Iraq and Afghanistan conflicts 5 6 7 8 Breeze J 1, Bowley DM 2, Combes JG 3, Baden J 4, Rickard RF 5, DuBose J 6, 9 10 Powers DB 7 11 12 13 14 1 Duke University Medical Center, Durham, North Carolina, USA. 15 16 [email protected] 17 2 University Hospitals Birmingham, Birmingham, UK. [email protected] 18 For peer review only 19 3 Royal Surrey County Hospital, Guildford, UK. [email protected] 20 4 21 University Hospitals Birmingham, Birmingham, UK. [email protected] 22 5 Academic Department of Military Surgery and Trauma, Royal Centre for Defence 23 24 Medicine, Birmingham, UK. [email protected] 25 26 6 Center for the Sustainment of Trauma and Readiness Skills, R Adams Cowley Shock 27 28 Trauma Center, Baltimore, Maryland, US. [email protected] 29 7 Duke University Medical Center, Durham, North Carolina, US. [email protected] 30 31 32 33 Keywords 34 35 Face; trauma; military; fracture; tracheostomy 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Abstract 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Objectives: To perform the first direct comparison of the facial injuries sustained and 5 6 treatment performed at United States (US) and United Kingdom (UK) deployed Medical 7 Treatment Facilities (MTF) in support of the military campaigns in Iraq and Afghanistan. 8 9 Setting: The US and UK Joint Theatre Trauma Registries were scrutinized for all patients 10 11 with facial injuries presenting alive to a UK or US deployed MTF between 01 March 2003 12 13 and 31 October 2011. 14 Participants: US and UK military personnel, local police, local military and civilians. 15 16 Primary and secondary outcome measures: An adjusted multiple logistic regression 17 18 model was performedFor using tracheostomypeer review as the primary only dependent outcome variable and 19 20 treatment in a US MTF, US or UK military, mandible fracture, and treatment of mandible 21 fracture as independent secondary variables. 22 23 Results: Facial injuries were identified in 16944 casualties, with the most common being 24 25 those to skin/muscle (64%), bone fractures (36%), inner/middle ear (28%) and intra-oral 26 damage (11%). Facial injuries were equally likely to undergo surgery in US MTF as UK 27 28 MTF (OR: 1.06, 95% CI: 0.4603 to 1.142, p= 0.6656), however, variations were seen in 29 30 injury type treated. In US MTF, 692/1452 (48%) of mandible fractures were treated by 31 2 32 either open or closed reduction compared to 0/167 (0%) in UK MTF (χ : 113.6; 33 p=<0.0001). US military casualties who had treatment of their mandible fracture (ORIF or 34 35 MMF) were less likely to have had a tracheostomy than those who did not undergo 36 37 stabilization of the fractured mandible (OR: 0.61, 95% CI: 0.44 to 0.86; p= 0.0066). http://bmjopen.bmj.com/ 38 39 Conclusions: The capability to surgically treat mandible fractures by open or closed 40 reduction should be considered as an integral component of deployed coalition surgical 41 42 care in the future. 43 44 Trial registration: not applicable. 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Strengths and limitations 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4  US MTF treated almost half of all mandible fractures prior to aeromedical 5 6 evacuation, whereas the UK MTF treated none. 7 8  US military casualties who had treatment of their mandible fracture were statistically 9 less likely to require a tracheostomy than those who did not. 10 11  This paper support accepted US military doctrine that mandible fractures should be 12 13 treated by open reduction in deployed MTF whenever agreed indications exist. 14 15  The lack of standardization between the two trauma registries limits further outcome 16 analyses between nations. 17 18  It is not possibleFor to collate peer long-term review outcome data only in the US system due to the lack 19 20 of uniformity of reporting methods. 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Introduction 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 In support of military operations in the Iraq and Afghanistan, the United States (US) and 5 6 United Kingdom (UK) deployed numerous military Medical Treatment Facilities (MTF). 7 Their primary role was to treat coalition military forces, but as the mission evolved, 8 9 treatment was offered to host nation police and military members, as well as the civilian 10 11 population according to the prevailing 'Rules of Eligibility’ (1). Coalition MTF deployed to 12 13 Iraq and Afghanistan are broadly classified by the North Atlantic Treaty Organization 14 (NATO) into Roles (or echelons). Role 1 provides primary health care with specialized first 15 16 aid, triage, resuscitation and stabilization (1,2). Role 2 MTF provide enhanced 17 18 resuscitation with capabilityFor forpeer life-saving review surgery, in addition only to further triage and 19 20 treatment of casualties. Role 2 facilities are divided into ‘Basic (R2B)’, where damage 21 control surgery (DCS) procedures can be undertaken, and ‘Enhanced’ (R2E) with 22 23 additional capabilities and greater resources, including the capability to prepare casualties 24 25 for strategic aeromedical evacuation (STRATEVAC) (1). Role 3 MTF provide all the 26 capabilities of the R2E MTF as well as the capability for specialized imaging and surgery, 27 28 blood banking and laboratory support. 29 30 31 32 The US military deployed surgeons formally trained in the management of facial skeletal 33 trauma to their Role 3 MTF at Balad (Iraq), Baghdad (Iraq) and Bagram (Afghanistan) 34 35 (3,4). Further management of facial trauma in US military personnel occurred following 36 37 STRATEVAC to Landstuhl Regional Medical Centre in Germany (Role 4), with a http://bmjopen.bmj.com/ 38 39 proportion further evacuated to homeland US facilities (Role 5) (4,5). The UK deployed 40 surgeons formally trained in the management of facial trauma to the R3 MTF in Camp 41 42 Bastion and, for a shorter period to the Canadian-led R3 MTF in (6–9). Taught 43 44 British practice was to repatriate patients with facial injury without stabilization or fixation of 45 the facial skeleton to the Royal Centre for Defence Medicine (RCDM) in Birmingham UK on September 29, 2021 by guest. Protected copyright. 46 47 (Role 4) (6,7,10–13). 48 49 50 51 Although both US and UK authors have previously published analyses of facial injuries 52 sustained in Iraq and Afghanistan, comparing the results is challenging due to 53 54 methodological differences. Accurate comparisons are relevant, as the US has a different 55 56 approach to the UK in terms of surgical training and the range of deployed surgical 57 58 specialties. This may have led to differences in the manner in which patients with facial 59 injuries were treated. Those studies describing treatment undertaken in deployed MTF 60 were generally based on a limited duration and/or utilized surgical logbooks that inevitably

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1 2 produce epidemiological and reporting bias (4,6–8,14). Existing papers can neither enable

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 comparison of treatment performed at different deployed facilities, nor between population 5 subtypes such as host nation civilians or military personnel (15,16). For example, between 6 7 2005-2010 the Canadian led MMU, during Operation ATHENA, treated 184 facial 8 9 fractures, but did not subdivide into fracture location or patient nationality (9). Finally, the 10 11 terminology used to describe the facial region has not been standardized between papers, 12 and includes ‘head and neck’, ‘craniomaxillofacial’, ‘craniofacial’ and ‘maxillofacial’ (17,18). 13 14 Analyses may include scalp and neck wounds, and these papers more often reflect the 15 16 specialty of surgeon treating the wounds and not the anatomical area (4,18). Potential 17 comparisons between treatment performed at US and UK MTF is enabled by both nations 18 For peer review only 19 utilizing databases, which record injuries using Abbreviated Injury Scale (AIS) scores 20 21 (16,17,19). To our knowledge, no authors have previously scrutinized the deployed trauma 22 23 registries of both nations to enable direct comparisons of injuries and treatment. The aim 24 of this analysis was therefore to compare incidence, injury types and treatment performed 25 26 in Iraq and Afghanistan during the conflicts on US and UK military and host-nation civilians 27 28 during an extended period in order to inform future surgical skill sets and training 29 30 requirements. 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Methods 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 With appropriate permissions from the US and UK chains of command, the US 5 6 Department of Defense Trauma Registry (DoDTR) and UK Joint Theatre Trauma Registry 7 (JTTR) databases were scrutinized to identify all patients with injuries to the facial region 8 9 (AIS region 2) sustained between 01 March 2003 and 31 October 2011. Died of Wounds 10 11 (DOW) was defined as casualties who died after reaching a MTF. During this period, both 12 13 US and UK military units were engaged in similar types of counter-insurgency warfare and 14 were wearing comparable types of personal armour. The Iraq conflict was described in the 15 16 databases as Operation Iraqi Freedom (US), Operation New Dawn (US) or Operation 17 18 TELIC (UK). The AfghanistanFor peer conflict was review described as Operationonly Enduring Freedom (US) 19 20 or (UK). Population groups studied were US, UK and other coalition 21 military, host nation military and civilians. Host nation military primarily comprised Iraqi or 22 23 Afghan National Army units. Host nation civilians included local police, such as the Afghan 24 25 National Police (ANP). 26 27 28 Injuries in both registries were matched using AIS codes (20). Within the AIS system, the 29 30 face is body region 2, and comprises the skin and soft tissues, the maxillofacial bony 31 32 skeleton, eyes and ears. Frontal bone, frontal sinus, head (scalp, cranial bones and 33 intracranial), and neck wounds were excluded from this analysis. AIS scoring of injuries in 34 35 the facial region ranges from 1-4 and, within this system, death cannot be directly 36 37 attributed to a facial injury. Treatment performed in deployed US MTF was coded using the http://bmjopen.bmj.com/ 38 39 International Classification of Disease version 9 (ICD-9) codes. Treatment performed in 40 deployed UK MTF was coded using the Classification of Interventions and Procedures 41 42 (OPCS) version 4. 43 44 45 An adjusted multiple logistic regression model was performed using tracheostomy as the on September 29, 2021 by guest. Protected copyright. 46 47 dependent variable and treatment in a US MTF, US or UK military, mandible fracture, and 48 49 treatment of mandible fracture as independent variables. Reverse stepwise logistic 50 51 regression was performed with a p-value threshold of <0.05 for inclusion in the model. 52 Odds ratios were determined using a Chi-Square test with Yates’ continuity correction, and 53 54 reported with p-values and confidence interval. Data analysis was performed using Stata 55 56 for Mac version 15.1 (StataCorp, USA). 57 58 59 60

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1 2 Results 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Patient demographics and injury mechanisms 5 6 Facial injuries were identified in 16944/67586 (25%) casualties who survived to reach a 7 deployed MTF across both databases (Table 1). 8792/ 16944 (52%) were recorded as due 8 9 to penetrating trauma, and 7702/16935 (45%) from blunt trauma. The most common 10 11 mechanisms of injury were explosive events (10700/16944, 63%), motor vehicle collisions 12 13 (2158/16944, 13%) and gunshot wounds (1685/16944, 10%, Table 2). 14 15 16 Types of facial injuries sustained in casualties that survived following treatment at 17 Role 2 and 3 MTFs 18 For peer review only 19 693/16944 (4%) patients with facial injuries who arrived alive at MTF died of wounds 20 21 (DoW) and 16251/16944 (96%) survived. The most common facial injuries in survivors 22 were to skin or muscle (10319/16251, 64%), facial bone fractures (5927/16251, 37%), 23 24 inner/middle ear damage (4486/16251, 28%) and trauma to intra-oral structures including 25 26 teeth (1782/16251, 11%, Table 3). 27 28 29 Treatment performed on survivors based upon population cohorts 30 Across both databases, 4653/16251 (29%) of survivors had procedures undertaken for 31 32 facial injuries in the deployed setting (Table 4). The most common was debridement of soft 33 34 tissues of skin and muscle (3879/4653, 83%), treatment of facial fractures (2217/4653, 35 36 48%) and surgical tracheostomy with facial injuries (1228/4653 (26%). Treatment of facial 37 fractures was divided into those managed by open reduction and internal fixation (ORIF) or http://bmjopen.bmj.com/ 38 39 those stabilized by mandibulo-maxillary fixation (MMF). A single casualty may have had 40 41 both ORIF and MMF for different fractures or to a single type of fracture, hence why the 42 43 totals for ORIF and MMF combined exceed the figure for either surgery alone. 44 45 Treatment performed on survivors based upon Medical Treatment Facility on September 29, 2021 by guest. Protected copyright. 46 47 Overall, patients with facial injuries were equally likely to undergo surgery in a US MTF 48 49 and a UK MTF (OR: 1.06, 95% CI: 0.46 to 1.14, p= 0.6656). However, some variation was 50 51 identified in injury type treated (Figure 1). Repair of skin/muscle injuries was 52 proportionately more commonly recorded in a UK MTF compared to a US MTF (OR: 53 54 1.465, 95% CI: 1.29 to 1.66, p= <0.0001). Repair of intra-oral injuries was more commonly 55 56 recorded in a US MTF compared to a UK MTF (OR: 1.706, 95% CI: 1.229 to 2.375, p= 57 58 <0.0020). Vascular injuries were also more commonly recorded as having been treated in 59 US MTF than UK MTF (231/367, 62.9% versus 19/42, 45.2%; p=0.0301). However, there 60 were more treatments recorded for facial vascular injuries in the US DoDTR than there

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1 2 were actual injuries recorded using AIS scores, demonstrating a discrepancy in recording.

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 1363/4189 (32.5%) of casualties (all patient cohorts) with facial fractures managed in US 5 MTF were treated by ORIF or stabilized by MMF. ORIF or formal MMF was not performed 6 7 in any of the 852 facial fractures seen in UK MTF. When analyzing mandible fractures 8 9 alone, in US MTF, 692/1452 (48%) of mandible fractures were stabilized compared to 10 2 11 7/167 (1%) in UK MTF (χ : 113.6; p=<0.0001). 258/692 (37%) of the patients with 12 stabilized mandible fractures in US MTF were treated by ORIF, the remainder stabilized by 13 14 MMF (Table 5). The seven mandible fractures temporarily stabilized in UK MTF were 15 16 treated with a bridle wire (a wire spanning the teeth around a fracture). No definitive 17 fixation was undertaken in a UK MTF. 18 For peer review only 19 20 21 22 Relationship between facial fracture treatment and aeromedical evacuation 23 It was not possible to accurately ascertain from the DoDTR the proportion of US military 24 25 casualties with facial fractures who were evacuated; however, all UK military personnel 26 27 recorded to have sustained a facial fracture underwent STRATEVAC out of theatre. 28 29 30 31 Relationship between mandible fracture treatment and provision of tracheostomy 32 33 34 The proportion of US military survivors with mandibular fractures having tracheostomy was 35 250/694 (36%) compared with 8/49 (16%) for UK military survivors; χ2: 6.989; p=<0.0082 36 37 (Table 5). Multiple logistic regression demonstrated that the odds of requiring a http://bmjopen.bmj.com/ 38 39 tracheostomy were highest in the presence of mandible fractures (OR: 7.7, 95% CI: 6.81 40 41 to 8.82, p<0.001) and casualties treated in US MTF instead of an UK MTF (OR: 2.17, 95% 42 CI: 1.37 to 3.42, p<0.001, Table 6). Local civilians were omitted from the analysis because 43 44 of collinearity. US military casualties who had treatment of their mandible fracture (ORIF or 45 on September 29, 2021 by guest. Protected copyright. 46 MMF) were less likely to have had a tracheostomy than those not treated (OR: 0.61, 95% 47 48 CI: 0.44 to 0.86; p= 0.0066). 49 50 Treatment of mandible fractures in Role 3 US Medical Treatment Facilities over time 51 52 There was a distinct shift in the US management of mandible fractures over time (Figure 53 54 2). There was a sharp increase in operative treatment between 2004 and 2006, and then a 55 56 gradual decline. The proportion of cases managed with closed reduction fell while there 57 was a concomitant increase in the use of ORIF, with the ratio changing from 3:2 to 1:2. 58 59 60

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1 2 Discussion 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 The face signals "gender, age, social and familial identity, ethnicity, emotion and much 5 6 more besides" (21). In the immediate aftermath of the First World War, injury to the face 7 with facial disfigurement was described in the lay press as 'the worst loss of all' (22). In the 8 9 Times History of WWI published in 1916, soldiers with facial injury and disfigurement were 10 11 described as "the most tragic of all war's victims" (23). Techniques of reconstruction are 12 13 radically different today; however, high quality management of patients with facial injury 14 remains a fundamental duty for military surgical teams. To our knowledge, this is the 15 16 largest analysis of patients with facial wounds treated in coalition MTF in Iraq and 17 18 Afghanistan. The studyFor breaks peer new ground review as it is the first only to directly compare treatment 19 20 delivered by US and UK military medical providers. The proportion of facial injuries was 21 higher than in most conflicts prior to the 21st century, likely reflecting the enhanced 22 23 effectiveness of helmets and body armour in reducing number and severity of head and 24 25 truncal injury and wounding patterns due to the use of improvised explosive devices later 26 in the Afghanistan conflict (17,24). The proportion of facial wounds was higher in local 27 28 civilians and local military, reflecting almost universal use of combat helmets by US and 29 30 UK military members and the use of ballistic eye protection from 2005 onwards (24). The 31 32 data in this study extends to 2011 only as military permissions to access data did not 33 extend beyond this. We acknowledge that there may be trends after date that might make 34 35 a difference to the incidence of injury, in particular for the UK military, such as the 36 37 introduction of the UK Mark 7 helmet at end of 2010, the patrol neck collar in 2013 (24), http://bmjopen.bmj.com/ 38 39 and the VIRTUS visor and mandible guard in 2015 (26). 40 41 42 Contrast is apparent between the management of facial fractures in US versus UK MTF. 43 44 The difference almost entirely related to the management of mandible fractures, with 45 692/1452 (48%) stabilized in Role 3 US MTF and (although 7/167 (1%) of mandible on September 29, 2021 by guest. Protected copyright. 46 47 fractures had a bridle wire placed in UK MTF), none had formal MMF or ORIF. This 48 49 reflected the accepted and taught practice in UK MTF (19,27–33). The US Department of 50 51 Defense (DoD) purposefully deployed US surgeons who regularly treated facial skeletal 52 trauma in their day-to-day role in mainland US. UK military plastic surgeons trained in 53 54 craniofacial injury management were deployed to the UK R3 MTF from 2008 onwards and 55 56 in addition, the UK deployed military OMF surgeons to the multi-national MTF in Kandahar. 57 58 This was a shared role with the Canadian military until 2010, with specialist surgeons 59 subsequently provided by the US Navy. Initial management of facial injury was taught to 60 deploying UK surgical teams on the Military Operational Surgical Training (MOST) pre-

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1 2 deployment course, which included stabilization of mandibular fractures with arch-bars

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 (27,28). Complete results from Kandahar are not included in this paper as, during the date 5 range studied, they are held in the Canadian deployed trauma care registry. However 6 7 published data demonstrated that MMF, ORIF and external fixation were performed by UK 8 9 OMF surgeons in Kandahar on both local military personnel and local civilians with 10 11 minimal recorded complications (6,7,29,30). At times, UK and other individuals injured in 12 the Area of Operations covered by the UK hospital at Camp Bastion who had significant 13 14 cranio-facial injury were flown directly to the MTF in Kandahar to enable specialist 15 16 neurosurgical care. 17 18 For peer review only 19 The sharp increase in in-theatre operative treatment of facial fractures by US forces, 20 21 including the proportionally greater use of ORIF compared to closed reduction between 22 23 2004 and 2006 coincided with the publication by Lopez et al. demonstrating the safety of 24 facial fracture repair in Iraq prior to evacuation (31). Although it did not become formal US 25 26 DoD policy, this principle was employed by many US deployed surgeons. The 27 28 effectiveness and safety of this approach has been further confirmed in multiple studies 29 30 (19,32–35). Such early management of facial fractures must be contrasted to those open 31 fractures of the limbs, which most authorities agree should not be treated by open fixation 32 33 early. The main stated contraindication to early definitive ORIF of facial fractures was that 34 35 it would potentially delay evacuation (31). The notion that a high energy transfer wound is 36 37 a contraindication to early ORIF of mandible fractures has now generally been discredited http://bmjopen.bmj.com/ 38 (36–39). Strong evidence exists that early management of such injuries is safe and leads 39 40 to improved outcomes (40). In fact, delaying treatment of facial fractures has been 41 42 demonstrated to increase patient pain, increase the likelihood of requiring a tracheostomy 43 and to result in poorer outcomes for complex fractures, particularly those with avulsive soft 44 45 tissue defects (5,35). Kittle et al. demonstrated that military patients with facial fractures on September 29, 2021 by guest. Protected copyright. 46 47 treated within two days of injury had lower complication rates and fewer returns to theatre 48 49 than those left longer than five days for treatment back in the US (5). This is particularly 50 relevant, as our results are derived from two conflicts in which rapid evacuation of US and 51 52 UK military personnel was possible, generally within 48 hours of injury (15,19,27,35). For 53 54 example, one analysis of UK military injuries during Iraq demonstrated a mean time period 55 between injury and treatment at Role 4 in Birmingham, UK of two days (41). The ability to 56 57 achieve rapid aeromedical evacuation is predicated on coalition air dominance in the 58 59 theater of operations with rapid tactical medical evacuation from point of wounding to the 60 Role 2 or Role 3 MTF (TACEVAC) and the ready availability of aircraft for strategic (out of

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1 2 theater) medical evacuation (STRATEVAC). The topography and weather conditions of

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 the Iraqi theatre of operations were generally acceptable for sustained flight operations, 5 with air dominance obtained early in the conflict and maintained throughout the entirety of 6 7 combat operations. In Afghanistan, TACEVAC was sometimes delayed due to weather 8 9 conditions and altitude restrictions in mountainous regions of the country. Future conflicts 10 11 are unlikely to see such rapid TACEVAC and STRATEVAC (27) and therefore treatment of 12 facial fractures, in forward MTF, may be required to mitigate preventable morbidity. 13 14 15 16 In US MTF, treating mandible fractures prior to STRATEVAC reduced the rate of 17 tracheostomy five-fold (64% to 13%). The US rate of tracheostomy placement for 18 For peer review only 19 mandibular fractures was 36% compared with 16% for UK-managed cases. Accepting 20 21 there is an absolute requirement for tracheostomy for some patients with mandibular 22 23 fracture and recognizing that surgeons in UK MTF did not fix any mandibular fractures and 24 placed tracheostomy in 16% of patients, these data could be interpreted to suggest that 25 26 some US military clinicians had a relatively low threshold to undertake tracheostomy. 27 28 There are however significant confounders to this hypothesis; in the UK area of operations 29 30 in Southern Afghanistan, with relatively small numbers of casualties, it was possible to 31 rapidly evacuate those casualties with facial fractures in an induced coma with either an 32 33 endotracheal tube or tracheostomy to protect the airway. Where delay may occur in future 34 35 conflicts and hence inpatient care may be required in theatre for longer, a relatively quick 36 37 operation (to stabilize the facial skeleton) may render a patient self-ventilating, rather than http://bmjopen.bmj.com/ 38 requiring high-dependency care, without the need for a tracheostomy ever to be placed. 39 40 41 42 A UK military multidisciplinary consensus statement from 2018 proposed that the surgical 43 skills required to manage facial injuries in a deployed MTF (Roles 1-3) in the first 24 hours 44 45 after injury are: facial vascular haemorrhage control, facial fracture stabilization, lateral on September 29, 2021 by guest. Protected copyright. 46 47 ocular canthotomy and surgical tracheostomy. This study reveals variation in the use of 48 49 tracheostomy after facial injury but supports the contention that the ability to stabilize facial 50 fractures soon after wounding offers the advantages of improved clinical outcomes and 51 52 can significantly reduce the requirement for tracheostomy. The authors recognize that a 53 54 major limitation of this study is the lack of standardization between the two trauma 55 registries, limiting further outcome analyses between nations. The components of midface 56 57 fractures (zygoma, maxilla, orbit) are coded individually, but may overlap, increasing the 58 59 incidence of individual fractures. In addition, it is not possible to collate long-term outcome 60 data in the US system due to the lack of uniformity of reporting methods, no national

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1 2 health database, and the loss of patients to the private sector once they leave, or are

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 retired from, military service. 5 6 7 This is the first study to have access to both US and UK trauma databases making true 8 9 comparisons between them possible. Our findings suggest that the capability to surgically 10 11 treat mandible fractures by ORIF and MMF should be considered as an integral 12 component of deployed coalition surgical care in the future. 13 14 15 16 Conflict of interest statement 17 We the authors can confirm that there are no conflicts of interest associated with this study 18 For peer review only 19 20 21 Ethical approval 22 23 Ethical approval was not required as this was a retrospective epidemiological study in 24 which all data has been anonymised and no patient identifiable data included. 25 26 27 28 Contributorship statement 29 30 Design: JB, JD, DP. 31 Analysis: JB, DB, DP. 32 33 Reporting: JB, DB, JB, JC, RR, JD, DP. 34 35 36 37 Competing interests statement http://bmjopen.bmj.com/ 38 There are no known competing interests associated with this study. 39 40 41 42 Funding statement 43 All members of this paper are in the employment of the MoD or DoD and no external 44 45 funding was provided for this research. on September 29, 2021 by guest. Protected copyright. 46 47 48 49 Data sharing statement 50 Due to the restricted access of these military databases, original data cannot be shared. 51 52 53 54 Patient and Public Involvement 55 Due to the restricted access of these military databases, patients and the public could not 56 57 involved in the reporting of this study. 58 59 60

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3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 5 6 US UK Other Other Host Host Host Host 7 military military coalition coalition nation nation nation nation 8 treated treated military military military military civilians civilians in US in UK treated treated treated treated treated treated 9 MTF MTF in US in UK in US in UK in US in UK 10 MTF MTF MTF MTF MTF MTF 11 12 Body area 13 Head, Face or 11146 740 1129 64 (37%) 4776 205 8342 543 14 Neck (Surv, (39%) (37%) (28%) (45%) (39%) (42%) (35%) 15 DOW) 16 17 Face only 6683 565 720 43 (25%) 3242 134 5235 322 18 (Surv, DOW) (23%)For(28%) peer(18%) review(30%) only(25%) (27%) (21%) 19 Location when 20 injured 21 22 Iraq 4741 110 101 7 (16%) 1718 8 (6%) 2890 17 (5%) 23 (71%) (19%) (14%) (53%) (55%) 24 Afghanistan 1942 455 619 36 (84%) 1524 126 2345 305 25 (29%) (81%) (86%) (47%) (94%) (45%) (95%) 26 27 Outcomes 28 Fatalities with 125 (2%) 21 (4%) 12 (2%) 0 (0%) 159 (5%) 11 (8%) 326 (6%) 39 (12%) 29 facial injuries 30 (DOW) 31 32 Patient 33 demographics 34 Mean age 25.8 (18- 25.6 (18- 26.7 (18- 26.9 (20- 26.1 (1- 23.9 (18- 26.7 (1- 21.3 (1- 35 (range) 60) 53) 54) 43) 85) 38) 89) 70) 36 37 Male (%) 6510 565 714 43 3236 134 4692 279 http://bmjopen.bmj.com/ 38 (97%) (100%) (99%) (100%) (100%) (100%) (90%) (87%) 39 Mechanism 40 41 Blunt 4241 124 290 16 (37%) 995 26 (19%) 1935 75 (23%) 42 (63%) (22%) (40%) (31%) (37%) 43 Penetrating 2317 367 (65) 417 27 (63%) 2142 108 3184 230 44 (35%) (58%) (66%) (81%) (61%) (71%) 45 on September 29, 2021 by guest. Protected copyright. 46 Other/unknown 125 (2%) 74 (23%) 13 (2%) 0 (0%) 105 (3%) 0 (0%) 116 (2%) 17(6%) 47 48 49 Table 1: Demographics of patients with facial injuries seen in all Role 2 or 3 Medical Treatment 50 51 Facilities (MTF). 52 53 54 55 56 57 58 59 60

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3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Mechanism US military UK military Other Host nation Host nation All 5 treated coalition military civilians 6 military 7 All battle 5303 512 655 2803 3990 13263 8 9 Explosive Device 4637 470 583 2182 2837 10709 10 GSW 349 39 40 465 792 1685 11 12 Motor Vehicle 116 0 2 71 178 367 13 Collision 14 Fall 29 3 2 6 16 56 15 16 Helicopter crash 38 0 8 7 9 62 17 Other/not 134 0 20 72 158 384 18 specified/unknown For peer review only 19 20 All non-battle 1380 53 108 573 1567 3681 21 Motor Vehicle 478 34 44 375 860 1791 22 Collision 23 24 Fall 240 5 7 38 173 463 25 Sharp object 26 0 3 3 28 60 26 27 Blunt object 142 0 9 3 46 200 28 Helicopter crash 39 10 5 1 3 58 29 30 Machinery/ 73 0 7 5 50 135 31 equipment 32 Other/not 382 4 33 148 407 974 33 specified/unknown 34 35 All 6683 565 763 3376 5557 16944 36 37 http://bmjopen.bmj.com/ 38 Table 2: Cause of battle and disease and non- battle injury (DNBI) in patients with a facial wound. 39 Incidences < 10 are not shown to ensure anonymity. 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from Group AIS 2005 US Military UK Military Other Host nation Host nation Totals 4 diagnosis Coalition Military Civilians 5 codes Military 6 ALL FACE 200099 - 6558 544 751 3206 5192 16251 7 WOUNDS 251902 8 9 All facial 250200- 2202 146 267 1318 1986 5919 fractures 251404, 10 251800- 11 251902 12 Mandible 250600 - 694 50 79 524 682 2029 13 fracture 250699 14 15 Maxilla 250800- 16 fracture 250810 1068 46 105 561 893 2673 17 Zygoma 251800- 18 Fracture 251814For peer682 review21 only66 362 590 1721 19 Orbital wall 251200 - 796 55 77 475 769 2172 20 fracture 251236 21 Nasal bone 251000, 667 34 71 319 437 1528 22 or septum 251002, 23 fracture 251006 24 Intraoral 243000- 851 54 89 293 495 1782 25 injury 250200, 26 251402- 27 251499 28 Facial skin 210099- 4692 343 390 1844 3050 10319 29 or muscle 216008 30 damage 31 Facial 220099, 46 2 1 26 33 108 32 vascular 220200- 33 injury 220204 34 Inner or 240205 - 1487 13 124 374 2488 4486 35 middle ear 240208 36 injury 37 http://bmjopen.bmj.com/ 38 39 Table 3: Injuries to the facial region sustained in survivors. 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Group 2015 ICD 9 OPCS-4 US UK Other Host Host 3 procedure procedure militar military coalitio nation nation BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 codes codes y n military civilian 5 military s 6 7 Open or closed 655 0 37 737 787 8 reduction of any 9 facial fracture 10 Open reduction 76.76 V15.2, V17.2, 258 0 8 179 404 11 of mandible V17.8, V17.9 12 fracture 13 14 Closed reduction 76.75 V15.3, V17.2, 140 0 15 84 113 15 of mandible V17.3 16 fracture 17 Open or closed 76.75, 76.76 V15.1, V15.2, 385 0 22 242 499 18 reduction of For peerV15.3, review V15.8, only 19 mandible V15.9, V17.3 20 fracture 21 22 Open or closed 76.73, 76.74 V08.1-V08.3, 115 0 4 73 101 23 reduction of V08.8, V08.9, 24 maxilla fracture V11.1-V11.4 25 26 Open reduction 76.71, 76.72 V09.3 83 0 2 77 105 of zygoma 27 fracture 28 29 Open reduction 16.01, 16.02, C08.2, C08.5 22 0 1 13 22 30 of orbital 16.09 31 fracture 32 33 Facial soft tissue 21.81, 24.32, S56.1 1859 206 188 605 1021 34 debridement/rep 25.51, 25.59, 35 air 26.41, 27.51- 36 27.61, 27.69 37 Ligation of facial 21.00-21.06, E12.1, L30.2 191 4 31 75 113 http://bmjopen.bmj.com/ 38 vessel 21.09, 38.12, 39 38.62, 38.82 40 41 Repair of intra 27.43-27.61, F40.4, F40.9 560 7 45 174 267 42 oral damage 27.69, 27.92- 43 27.99 44 Lateral 8.51 C11.6 83 4 13 47 77 45 canthotomy on September 29, 2021 by guest. Protected copyright. 46 47 Surgical 31.1, 31.12, E42.1, E42.3 323 13 29 361 502 48 tracheostomy 31.29, 31.74 49 with facial injury 50 51 52 Table 4: Overall numbers of surgical interventions performed on survivors in different casualty 53 54 populations. Numbers relate to patients treated, not to individual surgical procedures. 55 56 57 58 59 60

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1 2 Patient cohort US military UK military 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Survivors with mandible fractures 694 50 5 6 Survivors with mandible fractures having tracheostomy 250/694 (36%) 8/50 (16%) 7 Survivors with mandible fractures managed by ORIF or 382/694 (55%) 0/50 (0%) 8 MMF 9 10 Survivors with mandible fractures managed by ORIF or 51/382 (13.3%) 0/50 (0%) 11 MMF having tracheostomy 12 13 Survivors with mandible fractures not fixed having 199/312 (63.7%) 8/50 (16%) 14 tracheostomy 15 16 17 Table 5: Effect of Facial Fracture Treatment Upon provision of Tracheostomy in survivors to a Role 3 18 MTF; ORIF= Open ReductionFor Internal peer Fixation review (definitive treatment), only MMF= Maxillary Mandibular 19 Fixation (stabilisation). 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Tracheostomy Odds Ratio Standard z P>|z| Significant 95% Confidence Interval 5 Error 6 7 Treatment in 2.16603 0.5038496 3.32 0.001 Yes 1.372976 3.417167 US MTF 8 9 US military 0.4569846 0.0363172 -9.85 0 Yes 0.3910707 0.5340081 10 11 UK military 0.5354172 0.1981983 -1.69 0.091 No 0.2591782 1.106079 12 Other coalition 0.4006755 0.0812742 -4.51 0 Yes 0.2692357 0.5962838 13 military 14 15 Host nation 1.076235 0.0855536 0.92 0.355 No 0.9209632 1.257685 military 16 17 Host nation 1 (omitted) 18 civilians For peer review only 19 Mandible 7.747316 0.5124193 30.95 0 Yes 6.805366 8.819644 20 fracture 21 22 Maxilla fracture 2.993932 0.2370933 13.85 0 Yes 2.563505 3.496629 23 24 Zygoma 0.9881132 0.0941633 -0.13 0.9 No 0.8197672 1.19103 25 fracture 26 27 Table 6: Results of multivariate logistic regression analysis with tracheostomy as dependent variable 28 and all other variables as independent. 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 List of figures 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Figure 1: Proportions of different injury types found in survivors and treated according to 5 6 Medical Treatment Facility (MTF). Numbers relate to patients treated, not to individual 7 surgical procedures. 8 9 Figure 2: Proportions of all mandible fractures treated surgically over time in US Medical 10 11 Treatment Facilities. The vertical line in 2005 demonstrates when the paper by Lopez et al. 12 13 was published (31). 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 References 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 1. Ministry of Defence. Allied Joint Doctrine for Medical Support [Internet]. Allied Joint 5 6 Publication-4.10(B). 2015. Available from: 7 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attach 8 9 ment_data/file/457142/20150824-AJP_4_10_med_spt_uk.pdf 10 11 2. Bricknell M. For debate: the Operational Patient Care Pathway. J R Army Med Corps 12 13 [Internet]. 2014 Mar;160(1):64–9. Available from: 14 http://www.ncbi.nlm.nih.gov/pubmed/24478385 15 16 3. Chan RK, Siller-Jackson A, Verrett AJ, Wu J, Hale RG. Ten years of war: a 17 18 characterizationFor of craniomaxillofacial peer review injuries incurred only during operations Enduring 19 20 Freedom and Iraqi Freedom. J Trauma Acute Care Surg [Internet]. 2012 Dec;73(6 21 Suppl 5):S453-8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23192069 22 23 4. Powers DB. Distribution of civilian and military maxillofacial surgical procedures 24 25 performed in an Air Force theatre hospital: implications for training and readiness. J 26 R Army Med Corps [Internet]. 2010 Jun 1;156(2):117–21. Available from: 27 28 http://www.ncbi.nlm.nih.gov/pubmed/20648952 29 30 5. Kittle CP, Verrett AJ, Wu J, Mellus DE, Hale RG, Chan RK. Characterization of 31 32 midface fractures incurred in recent wars. J Craniofac Surg [Internet]. 2012 33 Nov;23(6):1587–91. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23172425 34 35 6. Breeze J, Monaghan AM, Williams MD, Clark RNW, Gibbons AJ. Five months of 36 37 surgery in the multinational field hospital in Afghanistan with an emphasis on oral http://bmjopen.bmj.com/ 38 39 and maxillofacial injuries. J R Army Med Corps [Internet]. 2010 Jun;156(2):125–8. 40 Available from: http://www.ncbi.nlm.nih.gov/pubmed/20648954 41 42 7. Breeze J, Gibbons AJ, Combes JG, Monaghan AM. Oral and maxillofacial surgical 43 44 contribution to 21 months of operating theatre activity in Kandahar Field Hospital: 1 45 February 2007-31 October 2008. Br J Oral Maxillofac Surg [Internet]. 2011 on September 29, 2021 by guest. Protected copyright. 46 47 Sep;49(6):464–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20889245 48 49 8. Maitland L, Lawton G, Baden J, Cubison T, Rickard R, Kay A, et al. The Role of 50 51 Military Plastic Surgeons in the Management of Modern Combat Trauma: An 52 Analysis of 645 Cases. Plast Reconstr Surg [Internet]. 2016 Apr;137(4):717e-724e. 53 54 Available from: http://www.ncbi.nlm.nih.gov/pubmed/27018700 55 56 9. Brisebois R, Hennecke P, Kao R, McAlister V, Po J, Stiegelmar R, et al. The Role 3 57 58 Multinational Medical Unit at Kandahar Airfield 2005-2010. Can J Surg. 2011 59 Dec;54(6):S124-9. 60 10. Breeze J, Gibbons AJ, Opie NJ, Monaghan A. Maxillofacial injuries in military

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1 2 personnel treated at the Royal Centre for Defence Medicine June 2001 to December

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 2007. Br J Oral Maxillofac Surg [Internet]. 2010 Dec;48(8):613–6. Available from: 5 http://www.ncbi.nlm.nih.gov/pubmed/19897288 6 7 11. Wordsworth M, Thomas R, Breeze J, Evriviades D, Baden J, Hettiaratchy S. The 8 9 surgical management of facial trauma in British soldiers during combat operations in 10 11 Afghanistan. Injury [Internet]. 2017 Jan;48(1):70–4. Available from: 12 http://www.ncbi.nlm.nih.gov/pubmed/27609650 13 14 12. Breeze J, Gibbons AJ, Hunt NC, Monaghan AM, Gibb I, Hepper A, et al. Mandibular 15 16 fractures in British military personnel secondary to blast trauma sustained in Iraq and 17 Afghanistan. Br J Oral Maxillofac Surg [Internet]. 2011 Dec;49(8):607–11. Available 18 For peer review only 19 from: http://www.ncbi.nlm.nih.gov/pubmed/21074305 20 21 13. Breeze J, McVeigh K, Lee JJ, Monaghan AM, Gibbons AJ. Management of 22 23 maxillofacial wounds sustained by British service personnel in Afghanistan. Int J Oral 24 Maxillofac Surg [Internet]. 2011 May;40(5):483–6. Available from: 25 26 http://www.ncbi.nlm.nih.gov/pubmed/21330106 27 28 14. Brennan J. Experience of first deployed otolaryngology team in Operation Iraqi 29 30 Freedom: the changing face of combat injuries. Otolaryngol Head Neck Surg 31 [Internet]. 2006 Jan;134(1):100–5. Available from: 32 33 http://www.ncbi.nlm.nih.gov/pubmed/16399188 34 35 15. Lew TA, Walker JA, Wenke JC, Blackbourne LH, Hale RG. Characterization of 36 37 craniomaxillofacial battle injuries sustained by United States service members in the http://bmjopen.bmj.com/ 38 current conflicts of Iraq and Afghanistan. J Oral Maxillofac Surg [Internet]. 2010 39 40 Jan;68(1):3–7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20006147 41 42 16. Wade AL, Dye JL, Mohrle CR, Galarneau MR. Head, face, and neck injuries during 43 operation Iraqi Freedom II: Results from the Us Navy-Marine Corps Combat Trauma 44 45 Registry. J Trauma - Inj Infect Crit Care [Internet]. 2007 Oct;63(4):836–40. Available on September 29, 2021 by guest. Protected copyright. 46 47 from: http://www.ncbi.nlm.nih.gov/pubmed/18090014 48 49 17. Breeze J, Gibbons AJ, Shieff C, Banfield G, Bryant DG, Midwinter MJ. Combat- 50 related craniofacial and cervical injuries: a 5-year review from the British military. J 51 52 Trauma [Internet]. 2011 Jul;71(1):108–13. Available from: 53 54 http://www.ncbi.nlm.nih.gov/pubmed/21336187 55 18. Xydakis MS, Fravell MD, Nasser KE, Casler JD. Analysis of battlefield head and 56 57 neck injuries in Iraq and Afghanistan. Otolaryngol Head Neck Surg [Internet]. 2005 58 59 Oct;133(4):497–504. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16213918 60 19. Lanigan A, Lindsey B, Maturo S, Brennan J, Laury A, Feldt BA, et al. The joint facial

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1 2 and invasive neck trauma (J-FAINT) project, Iraq and Afghanistan 2003-2011.

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Otolaryngol Head Neck Surg [Internet]. 2013 Mar;148(3):403–8. Available from: 5 http://www.ncbi.nlm.nih.gov/pubmed/23314163 6 7 20. Champion HR, Holcomb JB, Lawnick MM, Kelliher T, Spott MA, Galarneau MR, et 8 9 al. Improved characterization of combat injury. J Trauma [Internet]. 2010 10 11 May;68(5):1139–50. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20453770 12 21. Biernoff S. The Rhetoric of Disfigurement in First World War Britain. Soc Hist Med 13 14 [Internet]. 2011 Dec 1;24(3):666–85. Available from: 15 16 https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/hkq095 17 22. Worst Loss Of All. Manchester Evening Chronicle. 1918 Jun; 18 For peer review only 19 23. History of the War. The Times. 1916; 20 21 24. Breeze J, Allanson-Bailey LC, Hepper AE, Lewis EA. Novel method for comparing 22 23 coverage by future methods of ballistic facial protection. Br J Oral Maxillofac Surg 24 [Internet]. 2015 Jan;53(1):3–7. Available from: 25 26 http://www.ncbi.nlm.nih.gov/pubmed/25441496 27 28 25. McVeigh K, Breeze J, Jeynes P, Martin T, Parmar S, Monaghan AM. Clinical 29 30 strategies in the management of complex maxillofacial injuries sustained by British 31 military personnel. J R Army Med Corps. 2010 Jun;156(2):110–3. 32 33 26. Breeze J. The problems of protecting the neck from combat wounds. J R Army Med 34 35 Corps [Internet]. 2010 Sep;156(3):137–8. Available from: 36 37 http://www.ncbi.nlm.nih.gov/pubmed/20919611 http://bmjopen.bmj.com/ 38 27. Breeze J, Blanch R, Baden J, Monaghan AM, Evriviades D, Harrisson SE, et al. Skill 39 40 sets required for the management of military head, face and neck trauma: a 41 42 multidisciplinary consensus statement. J R Army Med Corps [Internet]. 2018 43 May;164(2):133–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/29326127 44 45 28. Breeze J, Combes JG, DuBose J, Powers DB. How are we currently training and on September 29, 2021 by guest. Protected copyright. 46 47 maintaining clinical readiness of US and UK military surgeons responsible for 48 49 managing head, face and neck wounds on deployment? J R Army Med Corps 50 [Internet]. 2018 Jul;164(3):183–5. Available from: 51 52 http://jramc.bmj.com/lookup/doi/10.1136/jramc-2018-000971 53 54 29. Gibbons AJ, Mackenzie N, Breederveld RS. Use of a custom designed external 55 fixator system to treat ballistic injuries to the mandible. Int J Oral Maxillofac Surg 56 57 [Internet]. 2011 Jan;40(1):103–5. Available from: 58 59 http://www.ncbi.nlm.nih.gov/pubmed/20846823 60 30. Gibbons AJ, Mackenzie N. Lessons learned in oral and maxillofacial surgery from

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1 2 British military deployments in Afghanistan. J R Army Med Corps [Internet]. 2010

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Jun;156(2):113–6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20648951 5 31. Lopez MA, Arnholt JL. Safety of definitive in-theater repair of facial fractures. Arch 6 7 Facial Plast Surg [Internet]. 2007;9(6):400–5. Available from: 8 9 http://www.ncbi.nlm.nih.gov/pubmed/18025350 10 11 32. Faulkner JA, Ferguson EE. Innovations in military handling of facial trauma. J 12 Craniofac Surg [Internet]. 2009 Jan;20(1):62–7. Available from: 13 14 http://www.ncbi.nlm.nih.gov/pubmed/19164991 15 16 33. Keller MW, Han PP, Galarneau MR, Gaball CW. Characteristics of maxillofacial 17 injuries and safety of in-theater facial fracture repair in severe combat trauma. Mil 18 For peer review only 19 Med [Internet]. 2015 Mar;180(3):315–20. Available from: 20 21 http://www.ncbi.nlm.nih.gov/pubmed/25735023 22 23 34. Brennan J. Head and neck trauma in Iraq and Afghanistan: different war, different 24 surgery, lessons learned. Laryngoscope [Internet]. 2013 Oct;123(10):2411–7. 25 26 Available from: http://doi.wiley.com/10.1002/lary.24096 27 28 35. Zachar MR, Labella C, Kittle CP, Baer PB, Hale RG, Chan RK. Characterization of 29 30 mandibular fractures incurred from battle injuries in Iraq and Afghanistan from 2001- 31 2010. J Oral Maxillofac Surg [Internet]. 2013 Apr;71(4):734–42. Available from: 32 33 http://www.ncbi.nlm.nih.gov/pubmed/23351482 34 35 36. Girotto JA, MacKenzie E, Fowler C, Redett R, Robertson B, Manson PN. Long-term 36 37 physical impairment and functional outcomes after complex facial fractures. Plast http://bmjopen.bmj.com/ 38 Reconstr Surg [Internet]. 2001 Aug;108(2):312–27. Available from: 39 40 http://www.ncbi.nlm.nih.gov/pubmed/11496168 41 42 37. Gruss JS, Antonyshyn O, Phillips JH. Early definitive bone and soft-tissue 43 reconstruction of major gunshot wounds of the face. Plast Reconstr Surg [Internet]. 44 45 1991 Mar;87(3):436–50. Available from: on September 29, 2021 by guest. Protected copyright. 46 47 http://www.ncbi.nlm.nih.gov/pubmed/1998014 48 49 38. Motamedi MHK. Primary management of maxillofacial hard and soft tissue gunshot 50 and shrapnel injuries. J Oral Maxillofac Surg [Internet]. 2003 Dec;61(12):1390–8. 51 52 Available from: http://www.ncbi.nlm.nih.gov/pubmed/14663802 53 54 39. Vayvada H, Menderes A, Yilmaz M, Mola F, Kzlkaya A, Atabey A. Management of 55 close-range, high-energy shotgun and rifle wounds to the face. J Craniofac Surg 56 57 [Internet]. 2005 Sep;16(5):794–804. Available from: 58 59 http://www.ncbi.nlm.nih.gov/pubmed/16192858 60 40. Peled M, Leiser Y, Emodi O, Krausz A. Treatment protocol for high velocity/high

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1 2 energy gunshot injuries to the face. Craniomaxillofac Trauma Reconstr [Internet].

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 2012 Mar;5(1):31–40. Available from: 5 http://www.ncbi.nlm.nih.gov/pubmed/23449809 6 7 41. Blanch RJ, Bindra MS, Jacks AS, Scott RAH. Ophthalmic injuries in British Armed 8 9 Forces in Iraq and Afghanistan. Eye (Lond) [Internet]. 2011 Feb;25(2):218–23. 10 11 Available from: http://www.ncbi.nlm.nih.gov/pubmed/21164529 12 13 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 STROBE Statement—checklist of items that should be included in reports of observational studies 3 4 5 Item Page Relevant text from 6 No. Recommendation No. manuscript 7 Title and abstract 1 (a) Indicate the study’s design with a commonly used term in the title or the abstract 4 8 (b) Provide in the abstract an informative and balanced summary of what was done and what was 2 9 10 found 11 Introduction 12 Background/rationale 2 Explain the scientificFor background peer and rationale for thereview investigation being reported only 2 13 14 Objectives 3 State specific objectives, including any prespecified hypotheses 3 15 Methods 16

Study design 4 Present key elements of study design early in the paper 4 http://bmjopen.bmj.com/ 17 18 Setting 5 Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, 19 follow-up, and data collection 20 Participants 6 (a) Cohort study—Give the eligibility criteria, and the sources and methods of selection of 4 21 22 participants. Describe methods of follow-up 23 Case-control study—Give the eligibility criteria, and the sources and methods of case 24 ascertainment and control selection. Give the rationale for the choice of cases and controls on September 29, 2021 by guest. Protected copyright. 25 Cross-sectional study—Give the eligibility criteria, and the sources and methods of selection of 26 27 participants 28 (b) Cohort study—For matched studies, give matching criteria and number of exposed and 29 unexposed 30 Case-control study—For matched studies, give matching criteria and the number of controls per 31 32 case 33 Variables 7 Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. 4 34 Give diagnostic criteria, if applicable 35 Data sources/ 8* For each variable of interest, give sources of data and details of methods of assessment 4 36 37 measurement (measurement). Describe comparability of assessment methods if there is more than one group 38 Bias 9 Describe any efforts to address potential sources of bias 6 39 Study size 10 Explain how the study size was arrived at 4 40 41 Continued on next page 42 1 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from

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1 2 Quantitative 11 Explain how quantitative variables were handled in the analyses. If applicable, describe which 4 3 variables groupings were chosen and why 4 5 Statistical 12 (a) Describe all statistical methods, including those used to control for confounding 4 6 methods (b) Describe any methods used to examine subgroups and interactions 4 7 (c) Explain how missing data were addressed 5 8 9 (d) Cohort study—If applicable, explain how loss to follow-up was addressed 4 10 Case-control study—If applicable, explain how matching of cases and controls was addressed 11 Cross-sectional study—If applicable, describe analytical methods taking account of sampling 12 strategy For peer review only 13 14 (e) Describe any sensitivity analyses 4 15 Results 16 Participants 13* (a) Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined 5 17 http://bmjopen.bmj.com/ 18 for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed 19 (b) Give reasons for non-participation at each stage 20 (c) Consider use of a flow diagram 21 Descriptive data 14* (a) Give characteristics of study participants (eg demographic, clinical, social) and information on 5 22 23 exposures and potential confounders 24 (b) Indicate number of participants with missing data for each variable of interest 5 on September 29, 2021 by guest. Protected copyright. 25 (c) Cohort study—Summarise follow-up time (eg, average and total amount) 5 26 27 Outcome data 15* Cohort study—Report numbers of outcome events or summary measures over time 5 28 Case-control study—Report numbers in each exposure category, or summary measures of exposure 29 Cross-sectional study—Report numbers of outcome events or summary measures 30 Main results 16 (a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision 5 31 32 (eg, 95% confidence interval). Make clear which confounders were adjusted for and why they were 33 included 34 (b) Report category boundaries when continuous variables were categorized 5 35 36 (c) If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time 37 period 38 Continued on next page 39 40 41 42 2 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from

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1 2 Other analyses 17 Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses 5 3 4 Discussion 5 Key results 18 Summarise key results with reference to study objectives 5 6 Limitations 19 Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss 6 7 both direction and magnitude of any potential bias 8 9 Interpretation 20 Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of 6 10 analyses, results from similar studies, and other relevant evidence 11 Generalisability 21 Discuss the generalisability (external validity) of the study results 6 12 For peer review only 13 Other information 14 Funding 22 Give the source of funding and the role of the funders for the present study and, if applicable, for the 7 15 original study on which the present article is based 16 17 http://bmjopen.bmj.com/ 18 *Give information separately for cases and controls in case-control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies. 19 20 Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and published examples of transparent reporting. The STROBE 21 22 checklist is best used in conjunction with this article (freely available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at 23 http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is available at www.strobe-statement.org. 24 25 on September 29, 2021 by guest. Protected copyright. 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 3 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from

Facial injury management undertaken at US and UK Medical Treatment Facilities during the Iraq and Afghanistan conflicts: A retrospective cohort study ForJournal: peerBMJ Open review only Manuscript ID bmjopen-2019-033557.R1

Article Type: Original research

Date Submitted by the 07-Nov-2019 Author:

Complete List of Authors: Breeze, John; Royal Centre for Defence Medicine, Royal Centre for Defence Medicine Bowley, Douglas; University Hospitals Birmingham NHS Foundation Trust Combes, James; Royal Surrey County Hospital NHS Foundation Trust Baden, James; University Hospitals Birmingham NHS Foundation Trust Rickard, Rory; Royal Centre for Defence Medicine DuBose, Joseph; R Adams Cowley Shock Trauma Center Powers, David; Duke University Medical Center

Primary Subject Surgery Heading:

Secondary Subject Heading: Dentistry and oral medicine http://bmjopen.bmj.com/ Military, Face, Trauma management < ORTHOPAEDIC & TRAUMA Keywords: SURGERY

on September 29, 2021 by guest. Protected copyright.

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1 2 Facial injury management undertaken at US and UK Medical Treatment 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Facilities during the Iraq and Afghanistan conflicts: A retrospective 5 6 cohort study 7 8 9 10 Breeze J 1, Bowley DM 2, Combes JG 3, Baden J 4, Rickard RF 5, DuBose J 6, 11 12 Powers DB 7 13 14 15 16 1 Duke University Medical Center, Durham, North Carolina, USA. 17 [email protected] 18 For peer review only 19 2 University Hospitals Birmingham, Birmingham, UK. [email protected] 20 21 3 Royal Surrey County Hospital, Guildford, UK. [email protected] 22 4 23 University Hospitals Birmingham, Birmingham, UK. [email protected] 24 5 Academic Department of Military Surgery and Trauma, Royal Centre for Defence 25 26 Medicine, Birmingham, UK. [email protected] 27 28 6 Center for the Sustainment of Trauma and Readiness Skills, R Adams Cowley Shock 29 30 Trauma Center, Baltimore, Maryland, US. [email protected] 31 7 Duke University Medical Center, Durham, North Carolina, US. [email protected] 32 33 34 35 Keywords 36 37 Face; trauma; military; fracture; tracheostomy http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Abstract 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Objectives: To perform the first direct comparison of the facial injuries sustained and 5 6 treatment performed at United States (US) and United Kingdom (UK) deployed Medical 7 Treatment Facilities (MTF) in support of the military campaigns in Iraq and Afghanistan. 8 9 Setting: The US and UK Joint Theatre Trauma Registries were scrutinized for all patients 10 11 with facial injuries presenting alive to a UK or US deployed MTF between 01 March 2003 12 13 and 31 October 2011. 14 Participants: US and UK military personnel, local police, local military and civilians. 15 16 Primary and secondary outcome measures: An adjusted multiple logistic regression 17 18 model was performedFor using tracheostomypeer review as the primary only dependent outcome variable and 19 20 treatment in a US MTF, US or UK military, mandible fracture, and treatment of mandible 21 fracture as independent secondary variables. 22 23 Results: Facial injuries were identified in 16944 casualties, with the most common being 24 25 those to skin/muscle (64%), bone fractures (36%), inner/middle ear (28%) and intra-oral 26 damage (11%). Facial injuries were equally likely to undergo surgery in US MTF as UK 27 28 MTF (OR: 1.06, 95% CI: 0.4603 to 1.142, p= 0.6656), however, variations were seen in 29 30 injury type treated. In US MTF, 692/1452 (48%) of mandible fractures were treated by 31 2 32 either open or closed reduction compared to 0/167 (0%) in UK MTF (χ : 113.6; 33 p=<0.0001). US military casualties who had treatment of their mandible fracture (ORIF or 34 35 MMF) were less likely to have had a tracheostomy than those who did not undergo 36 37 stabilization of the fractured mandible (OR: 0.61, 95% CI: 0.44 to 0.86; p= 0.0066). http://bmjopen.bmj.com/ 38 39 Conclusions: The capability to surgically treat mandible fractures by open or closed 40 reduction should be considered as an integral component of deployed coalition surgical 41 42 care in the future. 43 44 Trial registration: not applicable. 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Strengths and limitations 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4  This is the largest analysis of patients with facial wounds treated in coalition MTF in 5 6 Iraq and Afghanistan. 7 8  It is the first study to directly compare treatment delivered by US and UK military 9 medical providers. 10 11  It additionally reports data from local nationals enabling trends to be identified in 12 13 which facial fractures in particular were treated. 14 15  The lack of standardization between the two trauma registries limits further outcome 16 analyses between nations. 17 18  It is not possibleFor to collate peer long-term review outcome data only in the US system due to the lack 19 20 of uniformity of reporting methods. 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Introduction 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 In support of military operations in the Iraq and Afghanistan, the United States (US) and 5 6 United Kingdom (UK) deployed numerous military Medical Treatment Facilities (MTF). 7 Their primary role was to treat coalition military forces, but as the mission evolved, 8 9 treatment was offered to host nation police and military members, as well as the civilian 10 11 population according to the prevailing 'Rules of Eligibility’ (1). Coalition MTF deployed to 12 13 Iraq and Afghanistan are broadly classified by the North Atlantic Treaty Organization 14 (NATO) into Roles (or echelons). Role 1 provides primary health care with specialized first 15 16 aid, triage, resuscitation and stabilization (1,2). Role 2 MTF provide enhanced 17 18 resuscitation with capabilityFor forpeer life-saving review surgery, in addition only to further triage and 19 20 treatment of casualties. Role 2 facilities are divided into ‘Basic (R2B)’, where damage 21 control surgery (DCS) procedures can be undertaken, and ‘Enhanced’ (R2E) with 22 23 additional capabilities and greater resources, including the capability to prepare casualties 24 25 for strategic aeromedical evacuation (STRATEVAC) (1). Role 3 MTF provide all the 26 capabilities of the R2E MTF as well as the capability for specialized imaging and surgery, 27 28 blood banking and laboratory support. 29 30 31 32 The US military deployed surgeons formally trained in the management of facial skeletal 33 trauma to their Role 3 MTF at Balad (Iraq), Baghdad (Iraq) and Bagram (Afghanistan) 34 35 (3,4). Further management of facial trauma in US military personnel occurred following 36 37 STRATEVAC to Landstuhl Regional Medical Centre in Germany (Role 4), with a http://bmjopen.bmj.com/ 38 39 proportion further evacuated to homeland US facilities (Role 5) (4,5). The UK deployed 40 surgeons formally trained in the management of facial trauma to the R3 MTF in Camp 41 42 Bastion and, for a shorter period to the Canadian-led R3 MTF in Kandahar (6–9). Taught 43 44 British practice was to repatriate patients with facial injury without stabilization or fixation of 45 the facial skeleton to the Royal Centre for Defence Medicine (RCDM) in Birmingham UK on September 29, 2021 by guest. Protected copyright. 46 47 (Role 4) (6,7,10–13). 48 49 50 51 Although both US and UK authors have previously published analyses of facial injuries 52 sustained in Iraq and Afghanistan, comparing the results is challenging due to 53 54 methodological differences. Accurate comparisons are relevant, as the US has a different 55 56 approach to the UK in terms of surgical training and the range of deployed surgical 57 58 specialties. This may have led to differences in the manner in which patients with facial 59 injuries were treated. Those studies describing treatment undertaken in deployed MTF 60 were generally based on a limited duration and/or utilized surgical logbooks that inevitably

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1 2 produce epidemiological and reporting bias (4,6–8,14). Existing papers can neither enable

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 comparison of treatment performed at different deployed facilities, nor between population 5 subtypes such as host nation civilians or military personnel (15,16). For example, between 6 7 2005-2010 the Canadian led Role 3 MTF at Kandahar as part of Operation ATHENA 8 9 treated 184 facial fractures, but did not subdivide into fracture location or patient nationality 10 11 (9). Finally, the terminology used to describe the facial region has not been standardized 12 between papers, and includes ‘head and neck’, ‘craniomaxillofacial’, ‘craniofacial’ and 13 14 ‘maxillofacial’ (17,18). Analyses may include scalp and neck wounds, and these papers 15 16 more often reflect the specialty of surgeon treating the wounds and not the anatomical 17 area (4,18). Potential comparisons between treatment performed at US and UK MTF is 18 For peer review only 19 enabled by both nations utilizing databases, which record injuries using Abbreviated Injury 20 21 Scale (AIS) scores (16,17,19). To our knowledge, no authors have previously scrutinized 22 23 the deployed trauma registries of both nations to enable direct comparisons of injuries and 24 treatment. The aim of this analysis was therefore to compare incidence, injury types and 25 26 treatment performed in Iraq and Afghanistan during the conflicts on US and UK military 27 28 and host-nation civilians during an extended period in order to inform future surgical skill 29 30 sets and training requirements. 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Methods 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 All facial injuries (AIS region 2) sustained by patients between 01 March 2003 and 31 5 6 October 2011 were extracted from the US Department of Defense Trauma Registry 7 (DoDTR) and UK Joint Theatre Trauma Registry (JTTR) databases. Both databases are 8 9 held as spreadsheets on a secure military server in each country with highly restricted 10 11 access. Institutional approval was granted from the UK Royal Centre for Defence Medicine 12 13 and US Joint Trauma Registry for both interrogation of data and publication of results. 14 These dates were chosen for analysis as during that period both the US and UK were 15 16 undertaking similar combat roles and activities. The US had greater numbers of persons 17 18 treated at their MTFsFor as they peer had much reviewhigher numbers onlyof troops on the ground, reflecting 19 20 the relative sizes of their military commitments. Died of Wounds (DoW) was defined as 21 casualties who died after reaching an MTF. During this period, both US and UK military 22 23 units were engaged in similar types of counter-insurgency warfare and were wearing 24 25 comparable types of personal armour. The Iraq conflict was described in the databases as 26 Operation Iraqi Freedom (US), Operation New Dawn (US) or Operation TELIC (UK). The 27 28 Afghanistan conflict was described as Operation Enduring Freedom (US) or Operation 29 30 HERRICK (UK). Population groups studied were US, UK and other coalition military, host 31 32 nation military and civilians. Host nation military primarily comprised Iraqi or Afghan 33 National Army units. Host nation civilians included local police, such as the Afghan 34 35 National Police (ANP). 36 37 http://bmjopen.bmj.com/ 38 39 Injuries in both registries were matched using AIS codes (20). Within the AIS system, the 40 face is body region 2, and comprises the skin and soft tissues, the maxillofacial bony 41 42 skeleton, eyes and ears. Frontal bone, frontal sinus, head (scalp, cranial bones and 43 44 intracranial), and neck wounds were excluded from this analysis. The primary outcome 45 measure was requirement for surgical tracheostomy as with the exception of mortality, no on September 29, 2021 by guest. Protected copyright. 46 47 other measures exist for facial injuries in either database. AIS scoring of injuries in the 48 49 facial region ranges from 1-4 and, within this system, death cannot be directly attributed to 50 51 a facial injury (a score of 6 in the face and neck regions). Treatment performed in deployed 52 US MTF was coded using the International Classification of Disease version 9 (ICD-9) 53 54 codes. Treatment performed in deployed UK MTF was coded using the Classification of 55 56 Interventions and Procedures (OPCS) version 4. 57 58 59 Injury Severity Scores (ISS) were ISS split into terciles (tercile one = 3-15; tercile two = 16- 60 24; tercile three = 25-75). An adjusted multiple logistic regression model was performed

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1 2 using tracheostomy as the dependent variable and coalition casualty, ISS, mandible

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 fracture, and treatment of mandible fracture as independent variables. Reverse stepwise 5 logistic regression was performed with a p-value threshold of <0.05 for inclusion in the 6 7 model. Odds ratios were determined using a Chi-Square test with Yates’ continuity 8 9 correction, and reported with p-values and confidence interval. Data analysis was 10 11 performed using Stata for Mac version 15.1 (StataCorp, USA). 12 13 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Results 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Patient demographics and injury mechanisms 5 6 Facial injuries were identified in 16944/67586 (25%) casualties who survived to reach a 7 deployed MTF across both databases (Table 1). 8792/ 16944 (52%) were recorded as due 8 9 to penetrating trauma, and 7702/16935 (45%) from blunt trauma. The most common 10 11 mechanisms of injury were explosive events (10700/16944, 63%), motor vehicle collisions 12 13 (2158/16944, 13%) and gunshot wounds (1685/16944, 10%, Table 2). 14 15 16 Types of facial injuries sustained in casualties that survived following treatment at 17 Role 2 and 3 MTFs 18 For peer review only 19 693/16944 (4%) patients with facial injuries who arrived alive at MTF died of wounds 20 21 (DoW) and 16251/16944 (96%) survived. The most common facial injuries in survivors 22 were to skin or muscle (10319/16251, 64%), facial bone fractures (5927/16251, 37%), 23 24 inner/middle ear damage (4486/16251, 28%) and trauma to intra-oral structures including 25 26 teeth (1782/16251, 11%, Table 3). 27 28 29 Treatment performed on survivors based upon population cohorts 30 Across both databases, 4653/16251 (29%) of survivors had procedures undertaken for 31 32 facial injuries in the deployed setting (Table 4). The most common was debridement of soft 33 34 tissues of skin and muscle (3879/4653, 83%), treatment of facial fractures (2217/4653, 35 36 48%) and surgical tracheostomy with facial injuries (1228/4653 (26%). Treatment of facial 37 fractures was divided into those managed by open reduction and internal fixation (ORIF) or http://bmjopen.bmj.com/ 38 39 those stabilized by mandibulo-maxillary fixation (MMF). A single casualty may have had 40 41 both ORIF and MMF for different fractures or to a single type of fracture, hence why the 42 43 totals for ORIF and MMF combined exceed the figure for either surgery alone. 44 45 Treatment performed on survivors based upon Medical Treatment Facility on September 29, 2021 by guest. Protected copyright. 46 47 Overall, patients with facial injuries were equally likely to undergo surgery in a US MTF 48 49 and a UK MTF (OR: 1.06, 95% CI: 0.46 to 1.14, p= 0.6656). However, some variation was 50 51 identified in injury type treated (Figure 1). Repair of skin/muscle injuries was 52 proportionately more commonly recorded in a UK MTF compared to a US MTF (OR: 53 54 1.465, 95% CI: 1.29 to 1.66, p= <0.0001). Repair of intra-oral injuries was more commonly 55 56 recorded in a US MTF compared to a UK MTF (OR: 1.706, 95% CI: 1.229 to 2.375, p= 57 58 <0.0020). Vascular injuries were also more commonly recorded as having been treated in 59 US MTF than UK MTF (231/367, 62.9% versus 19/42, 45.2%; p=0.0301). However, there 60 were more treatments recorded for facial vascular injuries in the US DoDTR than there

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1 2 were actual injuries recorded using AIS scores, demonstrating a discrepancy in recording.

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 1363/4189 (32.5%) of casualties (all patient cohorts) with facial fractures managed in US 5 MTF were treated by ORIF or stabilized by MMF. ORIF or formal MMF was not performed 6 7 in any of the 852 facial fractures seen in UK MTF. When analyzing mandible fractures 8 9 alone, in US MTF, 692/1452 (48%) of mandible fractures were stabilized compared to 10 2 11 7/167 (1%) in UK MTF (χ : 113.6; p=<0.0001). 258/692 (37%) of the patients with 12 stabilized mandible fractures in US MTF were treated by ORIF, the remainder stabilized by 13 14 MMF (Table 5). The seven mandible fractures temporarily stabilized in UK MTF were 15 16 treated with a bridle wire (a wire spanning the teeth around a fracture). No definitive 17 fixation was undertaken in a UK MTF. 18 For peer review only 19 20 21 22 Relationship between facial fracture treatment and aeromedical evacuation 23 It was not possible to accurately ascertain from the DoDTR the proportion of US military 24 25 casualties with facial fractures who were evacuated; however, all UK military personnel 26 27 recorded to have sustained a facial fracture underwent STRATEVAC out of theatre. 28 29 30 31 Relationship between mandible fracture treatment and provision of tracheostomy 32 All casualties who had a tracheostomy reported in this study had it performed prior to evacuation; 33 34 however, the data cannot identify the exact temporal relation between tracheostomy and facial 35 36 fracture treatment. No tracheostomies were performed for respiratory weaning. The proportion of 37 US military survivors with mandibular fractures having tracheostomy was 250/694 (36%) compared http://bmjopen.bmj.com/ 38 39 with 8/49 (16%) for UK military survivors; χ2: 6.989; p=<0.0082 (Table 5). Multiple logistic 40 regression demonstrated that the odds of requiring a tracheostomy were highest in the presence of 41 42 mandible fractures (OR: 8.0, 95% CI: 6.88 to 9.34, p<0.001) and casualties treated in US MTF 43 44 instead of an UK MTF (OR: 3.03, 95% CI: 2.13 to 4.32, p<0.001, Table 6). ISS had no effect upon 45 the odds of having a tracheostomy. US military casualties who had treatment of their mandible on September 29, 2021 by guest. Protected copyright. 46 47 fracture (ORIF or MMF) were less likely to have had a tracheostomy than those not treated (OR: 48 0.61, 95% CI: 0.44 to 0.86; p= 0.0066). 49 50 51 52 Treatment of mandible fractures in Role 3 US Medical Treatment Facilities over time 53 There was a distinct shift in the US management of mandible fractures over time (Figure 54 55 2). There was a sharp increase in operative treatment between 2004 and 2006, and then a 56 57 gradual decline. The proportion of cases managed with closed reduction fell while there 58 59 was a concomitant increase in the use of ORIF, with the ratio changing from 3:2 to 1:2. 60

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1 2 Discussion 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 The face signals "gender, age, social and familial identity, ethnicity, emotion and much 5 6 more besides" (21). In the immediate aftermath of the First World War, injury to the face 7 with facial disfigurement was described in the lay press as 'the worst loss of all' (22). In the 8 9 Times History of WWI published in 1916, soldiers with facial injury and disfigurement were 10 11 described as "the most tragic of all war's victims" (23). Techniques of reconstruction are 12 13 radically different today; however, high quality management of patients with facial injury 14 remains a fundamental duty for military surgical teams. To our knowledge, this is the 15 16 largest analysis of patients with facial wounds treated in coalition MTF in Iraq and 17 18 Afghanistan. The studyFor breaks peer new ground review as it is the first only to directly compare treatment 19 20 delivered by US and UK military medical providers. The proportion of facial injuries was 21 higher than in most conflicts prior to the 21st century, likely reflecting the enhanced 22 23 effectiveness of helmets and body armour in reducing number and severity of head and 24 25 truncal injury and wounding patterns due to the use of improvised explosive devices later 26 in the Afghanistan conflict (17,24). The proportion of facial wounds was higher in local 27 28 civilians and local military, reflecting almost universal use of combat helmets by US and 29 30 UK military members and the use of ballistic eye protection from 2005 onwards (24). The 31 32 data in this study extends to 2011 only as military permissions to access data did not 33 extend beyond this. We acknowledge that there may be trends after date that might make 34 35 a difference to the incidence of injury, in particular for the UK military, such as the 36 37 introduction of the UK Mark 7 helmet at end of 2010, the patrol neck collar in 2013 (24), http://bmjopen.bmj.com/ 38 39 and the VIRTUS visor and mandible guard in 2015 (25). Although the UK had lower 40 volumes of facial injuries through their deployed MTFs, reflecting the lower proportions of 41 42 troops numbers, all evacuated coalition casualties were managed in a single Level 1/Major 43 44 Trauma Center in the UK (RCDM). This has enabled consolidation of institutional 45 knowledge and potentially optimized outcomes. on September 29, 2021 by guest. Protected copyright. 46 47 48 49 Contrast is apparent between the management of facial fractures in US versus UK MTF. 50 51 The difference almost entirely related to the management of mandible fractures, with 52 692/1452 (48%) stabilized in Role 3 US MTF and (although 7/167 (1%) of mandible 53 54 fractures had a bridle wire placed in UK MTF), none had formal MMF or ORIF. This 55 56 reflected the accepted and taught practice in UK MTF (19,26–32). The US Department of 57 58 Defense (DoD) purposefully deployed US surgeons who regularly treated facial skeletal 59 trauma in their day-to-day role in mainland US. UK military plastic surgeons were deployed 60 to the Role 2E MTF at Camp Bastion from 2008 but did not repair facial fractures on

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1 2 coalition military or local nationals. UK military OMF surgeons deployed to the Canadian

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 led Role 3 MTF in Kandahar from 2006 and repaired facial fractures and performed 5 surgical tracheostomies on local nationals but only stabilized coalition military as the policy 6 7 for this cohort was for rapid evacuation. Initial management of facial injury was taught to 8 9 deploying UK surgical teams on the Military Operational Surgical Training (MOST) pre- 10 11 deployment course, which included stabilization of mandibular fractures with arch-bars 12 (26,27). Complete results from Kandahar are not included in this paper as, during the date 13 14 range studied, they are held in the Canadian deployed trauma care registry. However 15 16 published data demonstrated that MMF, ORIF and external fixation were performed by UK 17 OMF surgeons in Kandahar on both local military personnel and local civilians with 18 For peer review only 19 minimal recorded complications (6,7,28,29). At times, UK and other individuals injured in 20 21 the Area of Operations covered by the UK hospital at Camp Bastion who had significant 22 23 cranio-facial injury were flown directly to the MTF in Kandahar to enable specialist 24 neurosurgical care. 25 26 27 28 The sharp increase in in-theatre operative treatment of facial fractures by US forces, 29 30 including the proportionally greater use of ORIF compared to closed reduction between 31 2004 and 2006 coincided with the publication by Lopez et al. demonstrating the safety of 32 33 facial fracture repair in Iraq prior to evacuation (30). Although it did not become formal US 34 35 DoD policy, this principle was employed by many US deployed surgeons. The 36 37 effectiveness and safety of this approach has been further confirmed in multiple studies http://bmjopen.bmj.com/ 38 (19,31–34). Such early management of facial fractures must be contrasted to those open 39 40 fractures of the limbs, which most authorities agree should not be treated by open fixation 41 42 early. The main stated contraindication to early definitive ORIF of facial fractures was that 43 it would potentially delay evacuation (30). The notion that a high energy transfer wound is 44 45 a contraindication to early ORIF of mandible fractures has now generally been discredited on September 29, 2021 by guest. Protected copyright. 46 47 (35–38). Strong evidence exists that early management of such injuries is safe and leads 48 49 to improved outcomes (39). In fact, delaying treatment of facial fractures has been 50 demonstrated to increase patient pain, increase the likelihood of requiring a tracheostomy 51 52 and to result in poorer outcomes for complex fractures, particularly those with avulsive soft 53 54 tissue defects (5,34). Kittle et al. demonstrated that military patients with facial fractures 55 treated within two days of injury had lower complication rates and fewer returns to theatre 56 57 than those left longer than five days for treatment back in the US (5). This is particularly 58 59 relevant, as our results are derived from two conflicts in which rapid evacuation of US and 60 UK military personnel was possible, generally within 48 hours of injury (15,19,26,34). For

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1 2 example, one analysis of UK military injuries during Iraq demonstrated a mean time period

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 between injury and treatment at Role 4 in Birmingham, UK of two days (40). The ability to 5 achieve rapid aeromedical evacuation is predicated on coalition air dominance in the 6 7 theater of operations with rapid tactical medical evacuation from point of wounding to the 8 9 Role 2 or Role 3 MTF (TACEVAC) and the ready availability of aircraft for strategic (out of 10 11 theater) medical evacuation (STRATEVAC). The topography and weather conditions of 12 the Iraqi theatre of operations were generally acceptable for sustained flight operations, 13 14 with air dominance obtained early in the conflict and maintained throughout the entirety of 15 16 combat operations. In Afghanistan, TACEVAC was sometimes delayed due to weather 17 conditions and altitude restrictions in mountainous regions of the country. Future conflicts 18 For peer review only 19 are unlikely to see such rapid TACEVAC and STRATEVAC (26) and therefore treatment of 20 21 facial fractures, in forward MTF, may be required to mitigate preventable morbidity. 22 23 24 In US MTF, treating mandible fractures prior to STRATEVAC reduced the rate of 25 26 tracheostomy five-fold (64% to 13%). The US rate of tracheostomy placement for 27 28 mandibular fractures was 36% compared with 16% for UK-managed cases. We accept 29 30 that there are requirements for tracheostomy in a small number of patients with mandibular 31 fractures, although clinicians at UK MTF were able to intubate the vast majority of coalition 32 33 casualties prior to evacuation. However, we believe that during this period the data 34 35 matches the experience of the authors, in that US military clinicians had a relatively low 36 37 threshold to undertake tracheostomy. Where delay may occur in future conflicts and hence http://bmjopen.bmj.com/ 38 inpatient care may be required in theatre for longer, a relatively quick operation to stabilize 39 40 the facial skeleton may render a patient self-ventilating, rather than requiring high- 41 42 dependency care, without the need for a tracheostomy ever to be placed. 43 44 45 A UK military multidisciplinary consensus statement from 2018 proposed that the surgical on September 29, 2021 by guest. Protected copyright. 46 47 skills required to manage facial injuries in a deployed MTF (Roles 1-3) in the first 24 hours 48 49 after injury are: facial vascular haemorrhage control, facial fracture stabilization, lateral 50 ocular canthotomy and surgical tracheostomy. This study reveals variation in the use of 51 52 tracheostomy after facial injury but supports the contention that the ability to stabilize facial 53 54 fractures soon after wounding offers the advantages of improved clinical outcomes and 55 can significantly reduce the requirement for tracheostomy. The authors recognize that a 56 57 major limitation of this study is the lack of standardization between the two trauma 58 59 registries, limiting further outcome analyses between nations. The components of midface 60 fractures (zygoma, maxilla, orbit) are coded individually, but may overlap, increasing the

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1 2 incidence of individual fractures. In addition, it is not possible to collate long-term outcome

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 data in the US system due to the lack of uniformity of reporting methods, no national 5 health database, and the loss of patients to the private sector once they leave, or are 6 7 retired from, military service. 8 9 10 11 This is the first study to have access to both US and UK trauma databases making true 12 comparisons between them possible. Our findings suggest that the capability to surgically 13 14 treat mandible fractures by ORIF and MMF should be considered as an integral 15 16 component of deployed coalition surgical care in the future. 17 18 For peer review only 19 Conflict of interest statement 20 21 We the authors can confirm that there are no conflicts of interest associated with this study 22 23 24 Ethical approval 25 26 Ethical approval was not required as this was a retrospective epidemiological study in 27 28 which all data has been anonymised and no patient identifiable data included. Approval for 29 30 this study was granted by the Research and Innovation Department of the Royal Centre 31 for Defence Medicine. 32 33 34 35 Author contribution statement (ICMJE criteria) 36 37 - Substantial contributions to the conception or design of the work; or the acquisition, http://bmjopen.bmj.com/ 38 analysis, or interpretation of data for the work: JB, DB, JB, JC, RR, JD, DP. 39 40 - Drafting the work or revising it critically for important intellectual content: JB, DB, JB, JC, 41 42 RR, JD, DP. 43 - Final approval of the version to be published: JB, DB, JB, JC, RR, JD, DP. 44 45 - Agreement to be accountable for all aspects of the work in ensuring that questions on September 29, 2021 by guest. Protected copyright. 46 47 related to the accuracy or integrity of any part of the work are appropriately investigated 48 49 and resolved: JB, DB, JB, JC, RR, JD, DP. 50 51 52 Competing interests statement 53 54 There are no known competing interests associated with this study. 55 56 57 Funding statement 58 59 All members of this paper are in the employment of the MoD or DoD and no external 60 funding was provided for this research.

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1 2

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Data availability statement 5 Due to the restricted access of these military databases, original data cannot be shared. 6 7 8 9 Patient and Public Involvement 10 11 Due to the restricted access of these military databases, patients and the public could not 12 involved in the reporting of this study. 13 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 5 6 US UK Other Other Host Host Host Host All 7 military military coalition coalition nation nation nation nation 8 treated treated military military military military civilians civilians in US in UK treated treated treated treated treated treated 9 MTF MTF in US in UK in US in UK in US in UK 10 MTF MTF MTF MTF MTF MTF 11 12 Body area 28935 2013 3965 171 10681 527 19737 1557 67586 13 (100%) (100%) (100%) (100%) (100%) (100%) (100%) (100% (100%) 14 Head, Face or 11146 740 1129 64 (37%) 4776 205 8342 543 26945 15 Neck (Surv, (39%) (37%) (28%) (45%) (39%) (42%) (35%) (40%) 16 DoW) 17 18 Face only 6683 For565 peer720 review43 (25%) 3242 only134 5235 322 16944 19 (Surv, DoW) (23%) (28%) (18%) (30%) (25%) (27%) (21%) (25%) 20 Location when 21 injured 22 23 Iraq 4741 110 101 7 (16%) 1718 8 (6%) 2890 17 (5%) 9592 24 (71%) (19%) (14%) (53%) (55%) (57%) 25 Afghanistan 1942 455 619 36 (84%) 1524 126 2345 305 7352 26 (29%) (81%) (86%) (47%) (94%) (45%) (95%) (43%) 27 28 Outcomes 29 Fatalities with 125 21 (4%) 12 (2%) 0 (0%) 159 11 (8%) 326 (6%) 39 (12%) 693 30 facial injuries (2%) (5%) (4%) 31 (DoW) 32 33 Patient 34 demographics 35 Mean age in 25.8 25.6 26.7 (18- 26.9 (20- 26.1 (1- 23.9 26.7 (1- 21.3 (1- 26.2 36 years (range) (18-60) (18-53) 54) 43) 85) (18-38) 89) 70) (1-89) 37 http://bmjopen.bmj.com/ 38 Male (%) 6510 565 714 43 3236 134 4692 279 16173 39 (97%) (100%) (99%) (100%) (100%) (100%) (90%) (87%) (95%) 40 Mechanism 41 42 Blunt 4241 124 290 16 (37%) 995 26 1935 75 (23%) 7702 43 (63%) (22%) (40%) (31%) (19%) (37%) (45%) 44 Penetrating 2317 367 417 27 (63%) 2142 108 3184 230 8792 45 (35%) (65) (58%) (66%) (81%) (61%) (71%) (52%) on September 29, 2021 by guest. Protected copyright. 46 47 Other/unknown 125 74 13 (2%) 0 (0%) 105 0 (0%) 116 (2%) 17(6%) 450 48 (2%) (23%) (3%) (3%) 49 50 51 Table 1: Demographics of patients with facial injuries seen in all Role 2 or 3 Medical Treatment 52 53 Facilities (MTF). 54 55 56 57 58 59 60

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1 2

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Mechanism US military UK military Other Host nation Host nation All 5 treated coalition military civilians 6 military 7 All battle 5303 (79%) 512 (90%) 655 (9%) 2803 (83%) 3990 (6%) 13263 (78%) 8 9 Explosive Device 4637 (69%) 470 (83%) 583 (8%) 2182 (65%) 2837 (5%) 10709 (63%) 10 GSW 349 (5%) 39 (7%) 40 (5%) 465 (14%) 792 (14%) 1685 (10%) 11 12 Motor Vehicle 116 (2%) 0 (0%) 2 (<1%) 71 (2%) 178 (3%) 367 (2%) 13 Collision 14 Fall 29 (<1%) 3 (<1%) 2 (<1%) 6 (<1%) 16 (<1%) 56 (<1%) 15 16 Helicopter crash 38 (<1%) 0 (0%) 8 (<1%) 7 (<1%) 9 (<1%) 62 (<1%) 17 Other/not 134 (2%) 0 (0%) 20 (3%) 72 (2%) 158 (3%) 384 (2%) 18 specified/unknown For peer review only 19 20 All non-battle 1380 (20%) 53 (10%) 108 (14%) 573 (17%) 1567 (28%) 3681 (22%) 21 Motor Vehicle 478 (7%) 34 (6%) 44 (5%) 375 (11%) 860 (15%) 1791 (11%) 22 Collision 23 24 Fall 240 (4%) 5 (1%) 7 (1%) 38 (1%) 173 (3%) 463 (3%) 25 Sharp object 26 (<1%) 0 (0%) 3 (<1%) 3 (<1%) 28 (<1%) 60 (<1%) 26 27 Blunt object 142 (2%) 0 (0%) 9 (1%) 3 (<1%) 46 (<1%) 200 (1%) 28 Helicopter crash 39 (<1%) 10 (2%) 5 (<1%) 1 (<1%) 3 (<1%) 58 (<1%) 29 30 Machinery/ 73 (1%) 0 (0%) 7 (<1%) 5 (<1%) 50 (<1%) 135 (<1%) 31 equipment 32 Other/not 382 (5%) 4 (<1%) 33 (4%) 148 (4%) 407 (7%) 974 (6%) 33 specified/unknown 34 35 All 6683 (100%) 565 (100%) 763 (100%) 3376 (100%) 5557 (100%) 16944 36 (100%) 37 http://bmjopen.bmj.com/ 38 39 Table 2: Cause of battle and disease and non- battle injury (DNBI) in patients with a facial wound. 40 Incidences < 10 are not shown to ensure anonymity. 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from Group AIS 2005 US Military UK Military Other Host nation Host nation Totals 4 diagnosis Coalition Military Civilians 5 codes Military 6 ALL FACE 200099 - 6558 (100%) 544 (100%) 751 (100%) 3206 (100%) 5192 (100%) 16251 7 WOUNDS 251902 (100%) 8 9 All facial 250200- 2202 (35%) 146 (27%) 267 (4%) 1318 (41%) 1986 (38%) 5919 (36%) fractures 251404, 10 251800- 11 251902 12 Mandible 250600 - 694 (11%) 50 (<1%) 79 (11%) 524 (16%) 682 (13%) 2029 (12%) 13 fracture 250699 14 15 Maxilla 250800- 16 fracture 250810 1068 (16%) 46 (<1%) 105 (14%) 561 (17%) 893 (18%) 2673 (16%) 17 Zygoma 251800- 18 Fracture 251814For peer682 (10%) review21 (<1%) 66 (9%)only362 (11%) 590 (11%) 1721 (11%) 19 Orbital wall 251200 - 796 (12%) 55 (1%) 77 (10%) 475 (15%) 769 (15%) 2172 (13%) 20 fracture 251236 21 Nasal bone 251000, 667 (10%) 34 (<1%) 71 (<1%) 319 (10%) 437 (8%) 1528 (9%) 22 or septum 251002, 23 fracture 251006 24 Intraoral 243000- 851 (13%) 54 (1%) 89 (12%) 293 (9%) 495 (10%) 1782 (11%) 25 injury 250200, 26 251402- 27 251499 28 Facial skin 210099- 4692 (72%) 343 (63%) 390 (52%) 1844 (58%) 3050 (6%) 10319 (63%) 29 or muscle 216008 30 damage 31 Facial 220099, 46 (<1%) 2 (<1%) 1 (<1%) 26 (<1%) 33 (<1%) 108 (<1%) 32 vascular 220200- 33 injury 220204 34 Inner or 240205 - 1487 (23%) 13 (<1%) 124 (17%) 374 (12%) 2488 (48%) 4486 (28%) 35 middle ear 240208 36 injury 37 http://bmjopen.bmj.com/ 38 39 Table 3: Injuries to the facial region sustained in in the 16251 survivors. Those 693 who DoW are 40 excluded. 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 Group 2015 ICD 9 OPCS-4 US UK Other Host Host 3 procedure procedure militar military coalitio nation nation BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 codes codes y n military civilian 5 military s 6 7 Open or closed 655 0 37 737 787 8 reduction of any 9 facial fracture 10 Open reduction 76.76 V15.2, V17.2, 258 0 8 179 404 11 of mandible V17.8, V17.9 12 fracture 13 14 Closed reduction 76.75 V15.3, V17.2, 140 0 15 84 113 15 of mandible V17.3 16 fracture 17 Open or closed 76.75, 76.76 V15.1, V15.2, 385 0 22 242 499 18 reduction of For peerV15.3, review V15.8, only 19 mandible V15.9, V17.3 20 fracture 21 22 Open or closed 76.73, 76.74 V08.1-V08.3, 115 0 4 73 101 23 reduction of V08.8, V08.9, 24 maxilla fracture V11.1-V11.4 25 26 Open reduction 76.71, 76.72 V09.3 83 0 2 77 105 of zygoma 27 fracture 28 29 Open reduction 16.01, 16.02, C08.2, C08.5 22 0 1 13 22 30 of orbital 16.09 31 fracture 32 33 Facial soft tissue 21.81, 24.32, S56.1 1859 206 188 605 1021 34 debridement/rep 25.51, 25.59, 35 air 26.41, 27.51- 36 27.61, 27.69 37 Ligation of facial 21.00-21.06, E12.1, L30.2 191 4 31 75 113 http://bmjopen.bmj.com/ 38 vessel 21.09, 38.12, 39 38.62, 38.82 40 41 Repair of intra 27.43-27.61, F40.4, F40.9 560 7 45 174 267 42 oral damage 27.69, 27.92- 43 27.99 44 Lateral 8.51 C11.6 83 4 13 47 77 45 canthotomy on September 29, 2021 by guest. Protected copyright. 46 47 Surgical 31.1, 31.12, E42.1, E42.3 323 13 29 361 502 48 tracheostomy 31.29, 31.74 49 with facial injury 50 51 52 Table 4: Overall numbers of surgical interventions performed on survivors in different casualty 53 54 populations. Numbers relate to patients treated, not to individual surgical procedures. 55 56 57 58 59 60

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1 2 Patient cohort US military UK military 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Survivors with mandible fractures 694 (100%) 50 (100%) 5 6 Survivors with mandible fractures having tracheostomy 250/694 (36%) 8/50 (16%) 7 Survivors with mandible fractures managed by ORIF or 382/694 (55%) 0/50 (0%) 8 MMF 9 10 Survivors with mandible fractures managed by ORIF or 51/382 (13.3%) 0/50 (0%) 11 MMF having tracheostomy 12 13 Survivors with mandible fractures not fixed having 199/312 (63.7%) 8/50 (16%) 14 tracheostomy 15 16 17 Table 5: Effect of Facial Fracture Treatment Upon provision of Tracheostomy in survivors to a Role 3 18 MTF; ORIF= Open ReductionFor Internal peer Fixation review (definitive treatment), only MMF= Maxillary Mandibular 19 Fixation (stabilisation). 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Tracheostomy Odds Standard z P>|z| 95% Confidence Interval 5 Ratio Error 6 7 Treatment in US 3.033696 0.5472023 6.15 0 2.13028 4.320235 MTF 8 9 Coalition military 0.4257238 0.0292904 -12.41 0 0.3720181 0.4871828 10 11 Mandible 8.021444 0.6257567 26.69 0 6.884143 9.346633 12 fracture present 13 No treatment of 0.7424999 0.0770788 -2.87 0.004 0.6058057 0.9100379 14 mandible 15 fracture 16 17 ISS group 3-15 0.1356279 0.0106448 -25.45 0 0.1162899 0.1581816 18 ISS group 16-24 0.4933107For0.0419693 peer-8.31 review0 only0.4175447 0.5828248 19 20 ISS group 25-75 1 (omitted) 21 22 23 Table 6: Results of multivariate logistic regression analysis with tracheostomy as dependent variable 24 and coalition military casualty (including US and UK), ISS grouping, mandible fracture, and no 25 26 treatment of mandible fracture as independent variables. 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 List of figures 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 Figure 1: Proportions of different injury types found in survivors and treated according to 5 6 Medical Treatment Facility (MTF). Numbers relate to patients treated, not to individual 7 surgical procedures. 8 9 Figure 2: Proportions of all mandible fractures treated surgically over time in US Medical 10 11 Treatment Facilities. The vertical line in 2005 demonstrates when the paper by Lopez et al. 12 13 was published (30). 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44 45 on September 29, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 References 3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 1. Ministry of Defence. Allied Joint Doctrine for Medical Support [Internet]. Allied Joint 5 6 Publication-4.10(B). 2015. Available from: 7 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attach 8 9 ment_data/file/457142/20150824-AJP_4_10_med_spt_uk.pdf 10 11 2. Bricknell M. For debate: the Operational Patient Care Pathway. J R Army Med Corps 12 13 [Internet]. 2014 Mar;160(1):64–9. Available from: 14 http://www.ncbi.nlm.nih.gov/pubmed/24478385 15 16 3. Chan RK, Siller-Jackson A, Verrett AJ, Wu J, Hale RG. Ten years of war: a 17 18 characterizationFor of craniomaxillofacial peer review injuries incurred only during operations Enduring 19 20 Freedom and Iraqi Freedom. J Trauma Acute Care Surg [Internet]. 2012 Dec;73(6 21 Suppl 5):S453-8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23192069 22 23 4. Powers DB. Distribution of civilian and military maxillofacial surgical procedures 24 25 performed in an Air Force theatre hospital: implications for training and readiness. J 26 R Army Med Corps. 2010 Jun 1;156(2):117–21. 27 28 5. Kittle CP, Verrett AJ, Wu J, Mellus DE, Hale RG, Chan RK. Characterization of 29 30 midface fractures incurred in recent wars. J Craniofac Surg [Internet]. 2012 31 32 Nov;23(6):1587–91. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23172425 33 6. Breeze J, Monaghan AM, Williams MD, Clark RNW, Gibbons AJ. Five months of 34 35 surgery in the multinational field hospital in Afghanistan with an emphasis on oral 36 37 and maxillofacial injuries. J R Army Med Corps [Internet]. 2010 Jun;156(2):125–8. http://bmjopen.bmj.com/ 38 39 Available from: http://www.ncbi.nlm.nih.gov/pubmed/20648954 40 7. Breeze J, Gibbons AJ, Combes JG, Monaghan AM. Oral and maxillofacial surgical 41 42 contribution to 21 months of operating theatre activity in Kandahar Field Hospital: 1 43 44 February 2007-31 October 2008. Br J Oral Maxillofac Surg. 2011 Sep;49(6):464–8. 45 8. Maitland L, Lawton G, Baden J, Cubison T, Rickard R, Kay A, et al. The Role of on September 29, 2021 by guest. Protected copyright. 46 47 Military Plastic Surgeons in the Management of Modern Combat Trauma: An 48 49 Analysis of 645 Cases. Plast Reconstr Surg [Internet]. 2016 Apr;137(4):717e-724e. 50 51 Available from: http://www.ncbi.nlm.nih.gov/pubmed/27018700 52 9. Brisebois R, Hennecke P, Kao R, McAlister V, Po J, Stiegelmar R, et al. The Role 3 53 54 Multinational Medical Unit at Kandahar Airfield 2005-2010. Can J Surg. 2011 55 56 Dec;54(6):S124-9. 57 58 10. Breeze J, Gibbons AJ, Opie NJ, Monaghan A. Maxillofacial injuries in military 59 personnel treated at the Royal Centre for Defence Medicine June 2001 to December 60 2007. Br J Oral Maxillofac Surg [Internet]. 2010 Dec;48(8):613–6. Available from:

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1 2 http://www.ncbi.nlm.nih.gov/pubmed/19897288

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 11. Wordsworth M, Thomas R, Breeze J, Evriviades D, Baden J, Hettiaratchy S. The 5 surgical management of facial trauma in British soldiers during combat operations in 6 7 Afghanistan. Injury [Internet]. 2017 Jan;48(1):70–4. Available from: 8 9 http://www.ncbi.nlm.nih.gov/pubmed/27609650 10 11 12. Breeze J, Gibbons AJ, Hunt NC, Monaghan AM, Gibb I, Hepper A, et al. Mandibular 12 fractures in British military personnel secondary to blast trauma sustained in Iraq and 13 14 Afghanistan. Br J Oral Maxillofac Surg [Internet]. 2011 Dec;49(8):607–11. Available 15 16 from: http://www.ncbi.nlm.nih.gov/pubmed/21074305 17 13. Breeze J, McVeigh K, Lee JJ, Monaghan AM, Gibbons AJ. Management of 18 For peer review only 19 maxillofacial wounds sustained by British service personnel in Afghanistan. Int J Oral 20 21 Maxillofac Surg [Internet]. 2011 May;40(5):483–6. Available from: 22 23 http://www.ncbi.nlm.nih.gov/pubmed/21330106 24 14. Brennan J. Experience of first deployed otolaryngology team in Operation Iraqi 25 26 Freedom: the changing face of combat injuries. Otolaryngol Head Neck Surg. 2006 27 28 Jan;134(1):100–5. 29 30 15. Lew TA, Walker JA, Wenke JC, Blackbourne LH, Hale RG. Characterization of 31 craniomaxillofacial battle injuries sustained by United States service members in the 32 33 current conflicts of Iraq and Afghanistan. J Oral Maxillofac Surg [Internet]. 2010 34 35 Jan;68(1):3–7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20006147 36 37 16. Wade AL, Dye JL, Mohrle CR, Galarneau MR. Head, face, and neck injuries during http://bmjopen.bmj.com/ 38 operation Iraqi Freedom II: Results from the Us Navy-Marine Corps Combat Trauma 39 40 Registry. J Trauma - Inj Infect Crit Care. 2007 Oct;63(4):836–40. 41 42 17. Breeze J, Gibbons AJ, Shieff C, Banfield G, Bryant DG, Midwinter MJ. Combat- 43 related craniofacial and cervical injuries: a 5-year review from the British military. J 44 45 Trauma. 2011 Jul;71(1):108–13. on September 29, 2021 by guest. Protected copyright. 46 47 18. Xydakis MS, Fravell MD, Nasser KE, Casler JD. Analysis of battlefield head and 48 49 neck injuries in Iraq and Afghanistan. Otolaryngol Head Neck Surg. 2005 50 Oct;133(4):497–504. 51 52 19. Lanigan A, Lindsey B, Maturo S, Brennan J, Laury A, Feldt BA, et al. The joint facial 53 54 and invasive neck trauma (J-FAINT) project, Iraq and Afghanistan 2003-2011. 55 Otolaryngol Head Neck Surg. 2013 Mar;148(3):403–8. 56 57 20. Champion HR, Holcomb JB, Lawnick MM, Kelliher T, Spott MA, Galarneau MR, et 58 59 al. Improved characterization of combat injury. J Trauma [Internet]. 2010 60 May;68(5):1139–50. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20453770

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1 2 21. Biernoff S. The Rhetoric of Disfigurement in First World War Britain. Soc Hist Med

3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 [Internet]. 2011 Dec 1;24(3):666–85. Available from: 5 https://academic.oup.com/shm/article-lookup/doi/10.1093/shm/hkq095 6 7 22. Worst Loss Of All. Manchester Evening Chronicle. 1918 Jun; 8 9 23. History of the War. The Times. 1916; 10 11 24. Breeze J, Allanson-Bailey LC, Hepper AE, Lewis EA. Novel method for comparing 12 coverage by future methods of ballistic facial protection. Br J Oral Maxillofac Surg 13 14 [Internet]. 2015 Jan;53(1):3–7. Available from: 15 16 http://www.ncbi.nlm.nih.gov/pubmed/25441496 17 25. Breeze J. The problems of protecting the neck from combat wounds. J R Army Med 18 For peer review only 19 Corps. 2010;156(3):137–8. 20 21 26. Breeze J, Blanch R, Baden J, Monaghan AM, Evriviades D, Harrisson SE, et al. Skill 22 23 sets required for the management of military head, face and neck trauma: a 24 multidisciplinary consensus statement. J R Army Med Corps. 2018 May;164(2):133– 25 26 8. 27 28 27. Breeze J, Combes JG, DuBose J, Powers DB. How are we currently training and 29 30 maintaining clinical readiness of US and UK military surgeons responsible for 31 managing head, face and neck wounds on deployment? J R Army Med Corps 32 33 [Internet]. 2018 Jul;164(3):183–5. Available from: 34 35 http://jramc.bmj.com/lookup/doi/10.1136/jramc-2018-000971 36 37 28. Gibbons AJ, Mackenzie N, Breederveld RS. Use of a custom designed external http://bmjopen.bmj.com/ 38 fixator system to treat ballistic injuries to the mandible. Int J Oral Maxillofac Surg 39 40 [Internet]. 2011 Jan;40(1):103–5. Available from: 41 42 http://www.ncbi.nlm.nih.gov/pubmed/20846823 43 29. Gibbons AJ, Mackenzie N. Lessons learned in oral and maxillofacial surgery from 44 45 British military deployments in Afghanistan. J R Army Med Corps [Internet]. 2010 on September 29, 2021 by guest. Protected copyright. 46 47 Jun;156(2):113–6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20648951 48 49 30. Lopez MA, Arnholt JL. Safety of definitive in-theater repair of facial fractures. Arch 50 Facial Plast Surg [Internet]. 2007;9(6):400–5. Available from: 51 52 http://www.ncbi.nlm.nih.gov/pubmed/18025350 53 54 31. Faulkner JA, Ferguson EE. Innovations in military handling of facial trauma. J 55 Craniofac Surg [Internet]. 2009 Jan;20(1):62–7. Available from: 56 57 http://www.ncbi.nlm.nih.gov/pubmed/19164991 58 59 32. Keller MW, Han PP, Galarneau MR, Gaball CW. Characteristics of maxillofacial 60 injuries and safety of in-theater facial fracture repair in severe combat trauma. Mil

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3 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from 4 33. Brennan J. Head and neck trauma in Iraq and Afghanistan: different war, different 5 surgery, lessons learned. Laryngoscope. 2013 Oct;123(10):2411–7. 6 7 34. Zachar MR, Labella C, Kittle CP, Baer PB, Hale RG, Chan RK. Characterization of 8 9 mandibular fractures incurred from battle injuries in Iraq and Afghanistan from 2001- 10 11 2010. J Oral Maxillofac Surg [Internet]. 2013 Apr;71(4):734–42. Available from: 12 http://www.ncbi.nlm.nih.gov/pubmed/23351482 13 14 35. Girotto JA, MacKenzie E, Fowler C, Redett R, Robertson B, Manson PN. Long-term 15 16 physical impairment and functional outcomes after complex facial fractures. Plast 17 Reconstr Surg [Internet]. 2001 Aug;108(2):312–27. Available from: 18 For peer review only 19 http://www.ncbi.nlm.nih.gov/pubmed/11496168 20 21 36. Gruss JS, Antonyshyn O, Phillips JH. Early definitive bone and soft-tissue 22 23 reconstruction of major gunshot wounds of the face. Plast Reconstr Surg [Internet]. 24 1991 Mar;87(3):436–50. Available from: 25 26 http://www.ncbi.nlm.nih.gov/pubmed/1998014 27 28 37. Motamedi MHK. Primary management of maxillofacial hard and soft tissue gunshot 29 30 and shrapnel injuries. J Oral Maxillofac Surg [Internet]. 2003 Dec;61(12):1390–8. 31 Available from: http://www.ncbi.nlm.nih.gov/pubmed/14663802 32 33 38. Vayvada H, Menderes A, Yilmaz M, Mola F, Kzlkaya A, Atabey A. Management of 34 35 close-range, high-energy shotgun and rifle wounds to the face. J Craniofac Surg 36 37 [Internet]. 2005 Sep;16(5):794–804. Available from: http://bmjopen.bmj.com/ 38 http://www.ncbi.nlm.nih.gov/pubmed/16192858 39 40 39. Peled M, Leiser Y, Emodi O, Krausz A. Treatment protocol for high velocity/high 41 42 energy gunshot injuries to the face. Craniomaxillofac Trauma Reconstr [Internet]. 43 2012 Mar;5(1):31–40. Available from: 44 45 http://www.ncbi.nlm.nih.gov/pubmed/23449809 on September 29, 2021 by guest. Protected copyright. 46 47 40. Blanch RJ, Bindra MS, Jacks AS, Scott RAH. Ophthalmic injuries in British Armed 48 49 Forces in Iraq and Afghanistan. Eye (Lond). 2011 Feb;25(2):218–23. 50 51 52 53 54 55 56 57 58 59 60

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1 2 STROBE Statement—checklist of items that should be included in reports of observational studies 3 4 5 Item Page Relevant text from 6 No. Recommendation No. manuscript 7 Title and abstract 1 (a) Indicate the study’s design with a commonly used term in the title or the abstract 4 8 (b) Provide in the abstract an informative and balanced summary of what was done and what was 2 9 10 found 11 Introduction 12 Background/rationale 2 Explain the scientificFor background peer and rationale for thereview investigation being reported only 2 13 14 Objectives 3 State specific objectives, including any prespecified hypotheses 3 15 Methods 16

Study design 4 Present key elements of study design early in the paper 4 http://bmjopen.bmj.com/ 17 18 Setting 5 Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, 19 follow-up, and data collection 20 Participants 6 (a) Cohort study—Give the eligibility criteria, and the sources and methods of selection of 4 21 22 participants. Describe methods of follow-up 23 Case-control study—Give the eligibility criteria, and the sources and methods of case 24 ascertainment and control selection. Give the rationale for the choice of cases and controls on September 29, 2021 by guest. Protected copyright. 25 Cross-sectional study—Give the eligibility criteria, and the sources and methods of selection of 26 27 participants 28 (b) Cohort study—For matched studies, give matching criteria and number of exposed and 29 unexposed 30 Case-control study—For matched studies, give matching criteria and the number of controls per 31 32 case 33 Variables 7 Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. 4 34 Give diagnostic criteria, if applicable 35 Data sources/ 8* For each variable of interest, give sources of data and details of methods of assessment 4 36 37 measurement (measurement). Describe comparability of assessment methods if there is more than one group 38 Bias 9 Describe any efforts to address potential sources of bias 6 39 Study size 10 Explain how the study size was arrived at 4 40 41 Continued on next page 42 1 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from

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1 2 Quantitative 11 Explain how quantitative variables were handled in the analyses. If applicable, describe which 4 3 variables groupings were chosen and why 4 5 Statistical 12 (a) Describe all statistical methods, including those used to control for confounding 4 6 methods (b) Describe any methods used to examine subgroups and interactions 4 7 (c) Explain how missing data were addressed 5 8 9 (d) Cohort study—If applicable, explain how loss to follow-up was addressed 4 10 Case-control study—If applicable, explain how matching of cases and controls was addressed 11 Cross-sectional study—If applicable, describe analytical methods taking account of sampling 12 strategy For peer review only 13 14 (e) Describe any sensitivity analyses 4 15 Results 16 Participants 13* (a) Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined 5 17 http://bmjopen.bmj.com/ 18 for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed 19 (b) Give reasons for non-participation at each stage 20 (c) Consider use of a flow diagram 21 Descriptive data 14* (a) Give characteristics of study participants (eg demographic, clinical, social) and information on 5 22 23 exposures and potential confounders 24 (b) Indicate number of participants with missing data for each variable of interest 5 on September 29, 2021 by guest. Protected copyright. 25 (c) Cohort study—Summarise follow-up time (eg, average and total amount) 5 26 27 Outcome data 15* Cohort study—Report numbers of outcome events or summary measures over time 5 28 Case-control study—Report numbers in each exposure category, or summary measures of exposure 29 Cross-sectional study—Report numbers of outcome events or summary measures 30 Main results 16 (a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision 5 31 32 (eg, 95% confidence interval). Make clear which confounders were adjusted for and why they were 33 included 34 (b) Report category boundaries when continuous variables were categorized 5 35 36 (c) If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time 37 period 38 Continued on next page 39 40 41 42 2 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 BMJ Open: first published as 10.1136/bmjopen-2019-033557 on 25 November 2019. Downloaded from

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1 2 Other analyses 17 Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses 5 3 4 Discussion 5 Key results 18 Summarise key results with reference to study objectives 5 6 Limitations 19 Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss 6 7 both direction and magnitude of any potential bias 8 9 Interpretation 20 Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of 6 10 analyses, results from similar studies, and other relevant evidence 11 Generalisability 21 Discuss the generalisability (external validity) of the study results 6 12 For peer review only 13 Other information 14 Funding 22 Give the source of funding and the role of the funders for the present study and, if applicable, for the 7 15 original study on which the present article is based 16 17 http://bmjopen.bmj.com/ 18 *Give information separately for cases and controls in case-control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies. 19 20 Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and published examples of transparent reporting. The STROBE 21 22 checklist is best used in conjunction with this article (freely available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at 23 http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is available at www.strobe-statement.org. 24 25 on September 29, 2021 by guest. Protected copyright. 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 3 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60