A Comparison of Deployed Occupational Tasks Performed by Different Types of Military Battalions and Resulting Low Back Pain
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MILITARY MEDICINE, 178, 8:e937, 2013 A Comparison of Deployed Occupational Tasks Performed by Different Types of Military Battalions and Resulting Low Back Pain MAJ Tanja C. Roy, SP USA*; CPT Heather P. Lopez, SP USA† ABSTRACT With deployment Soldiers must now wear body armor and additional equipment while performing occupational tasks, representing a large demand that has not been considered when studying military occupations. The purpose of this study was to: (1) describe tasks required by different occupational battalions within a Brigade Downloaded from https://academic.oup.com/milmed/article/178/8/e937/4259694 by guest on 04 October 2021 Combat Team; (2) establish the incidence of low back pain (LBP) in each battalion and; (3) determine which tasks predict LBP within the different battalions. This was a prospective cohort study investigating 805 Soldiers in a Brigade Combat Team deployed to Afghanistan for 1 year. Demographic, occupational, and fitness variables were recorded. There was no difference in time spent on fitness training between the battalions. Occupational tasks performed by deployed Soldiers vary in the level of physical demand between battalions. Infantry had the highest fitness score (257); wore the heaviest equipment (70 lb.); spent the most time wearing body armor (49 hours/week), performing dismounted patrol (29 hours/week), and lifting objects (35 hours/week); spent the least amount of time working at a desk (14 hours/week); but had a similar incidence of LBP (77%) compared to other battalions. History of LBP and time spent wearing body armor were the two most consistent predictors of LBP across battalion types. INTRODUCTION Artillery (FA); (3) Reconnaissance, Surveillance, and Target With the U.S. military engaged in conflicts in Iraq and Acquisition (RSTA); (4) Brigade Special Troops Battalion Afghanistan over the last 10 years, Soldiers spend more time (BSTB); and (5) Brigade Support Battalion (BSB). Research conducting combat operations than during the previous studies providing normative data on occupational demands decade. Over two million service members (Army, Navy, in deployed U.S. Soldiers are scarce. Dean2 investigated only Marines, and Air Force) have deployed in the last 10 years tasks performed on patrol, but not tasks performed inside with 40% of service members deploying more than once.1 the forward operating base, in an Infantry Battalion in This shift from garrison activities to combat operations has Afghanistan. Other types of occupational battalions have resulted in a change in occupational tasks performed by Sol- not been studied, nor have tasks performed inside the forward diers. Deployed Soldiers must now wear body armor and operating base in deployed environments been evaluated. additional equipment even while working inside the forward Epidemiological data show that changes in operational operating base perimeter, representing a significant occupa- tempo over the last decade have resulted in an increase in tional demand that was not considered when studying occu- musculoskeletal injuries.3 Medical discharges because of pational specific tasks in the past. musculoskeletal injuries have increased over sevenfold in The Army’s basic deployable units are called Brigade the last 20 years with combined musculoskeletal injuries Combat Teams (BCT). Within an Infantry BCT there are currently accounting for 78% of medical discharges from five different types of battalions each with different occupa- the military.4 Of these musculoskeletal injuries, the low back tional task requirements: (1) Infantry Battalion (IN); (2) Field is the most commonly injured anatomical region both in deployed and nondeployed environments.5–7 In fact, low back injuries have the highest risk of permanent disability of *U.S. Army Research Institute of Environmental Medicine, 15 Kansas all musculoskeletal injuries.8 Low back pain (LBP) is more St., Natick, MA 01760. †2nd Brigade Combat Team, 101st Airborne Division, Fort Campbell, prevalent while deployed (21.2% in Afghanistan, 26.9% in KY 42223. Bosnia, and 23.2% in Iraq) compared to 17.8% (includes 5,6,9,10 Approved for public release: distribution is unlimited. The opinions or back and abdomen) in nondeployed military members. assertions contained herein are the private views of the author(s) and are not No study has yet described the risk of injury resulting to be construed as official or reflecting the views of the Army or the Depart- from physical tasks in Soldiers within different occupations ment of Defense. The investigators have adhered to the policies for protec- tion of human subjects as prescribed in Army Regulation 70-25, and the in deployed environments. Studies done in nondeployed research was conducted in adherence with the provisions of 32 CFR Part environments have found that Infantrymen, medical equip- 219. Human subjects participated in these studies after giving their free ment repairers, and light-wheeled vehicle mechanics have and informed voluntary consent. Investigators adhered to AR 70-25 and the highest rate of musculoskeletal injury and hospitaliza- USAMRMC Regulation 70-25 on the use of volunteers in research. Any tion in garrison.11 A more recent study found that Soldiers citations of commercial organizations and trade names in this report do not constitute an official department of the Army endorsement of approval of the within the United States in occupations classified as “heavy products or services of these organizations. demand” (occasional lifting of over 100 lb and frequent doi: 10.7205/MILMED-D-12-00539 liftingover50lb)hadanincreased risk of hospitalization MILITARY MEDICINE, Vol. 178, August 2013 e937 Case Report compared to those in occupations classified as “light” (lift a occupational tasks, demographic information, as well as maximum of 20 lb with frequent lifting of 10 lb).12 Although LBP. One way between subjects analysis of variance occupational requirements involving wear of body armor, (ANOVA) was performed for each continuous occupational physical training, and excessive load carriage are also variable as a function of battalion type. Assumptions for this known risk factors for musculoskeletal injury, such factors model were evaluated, followed by an omnibus F test. If the have not been previously considered when characterizing F test was significant, pairwise comparisons using Tukey’s the physical demands level of military occupations for Honestly Significant Difference were performed to detect research.13–15 In addition, no studies have investigated the the pattern of differences. The assumption of homogeneity difference in injury rates between occupational battalions was violated for APFT; equipment weight; and time spent while deployed. working at a desk, lifting objects greater than 30 lb, dis- The purpose of this study was therefore threefold: (1) to mounted patrol, and riding in tactical vehicles. So an F test describe occupational tasks performed by different types of with Brown–Forsythe adjustment was conducted, then the Downloaded from https://academic.oup.com/milmed/article/178/8/e937/4259694 by guest on 04 October 2021 occupational battalions within a BCT deployed to Afghanistan, pairwise comparisons were performed using the Games- (2) to establish the incidence of LBP in each battalion, and Howell procedure. (3) to establish which occupational tasks predict the occur- Logistic regression was then used to identify the best pre- rence of LBP in deployed Soldiers operating within the dictors for the incidence of LBP (yes or no) in each battalion different types of occupational battalions. with more than 75 Soldiers. Logistic regression was not cal- culated for the FA as the sample was too small. All variables METHODS were originally entered into each logistic regression model. This prospective cohort study was conducted in one BCT For cardiovascular training, core training, and strength train- from June 2009 to August 2010. Institutional Review Board ing predeployment values were used. All variables with a approval was obtained from Brooke Army Medical Center. regression coefficient p value of greater than 0.1 were then All Soldiers deploying as a member of the BCT were invited removed. The remaining variables were then removed and to participate as a part of their predeployment Soldier added to the logistic equation in different combinations in Readiness Process. Current LBP was considered an exclu- order to find the most parsimonious combination of variables sion criterion as these Soldiers would not be considered significantly contributing to the prediction of the incidence incident cases. of LBP in each battalion. All 1,194 participants filled out a predeployment survey as a station during their predeployment Soldier Readiness RESULTS Process in the month before deployment. A modified version Before deployment 1,194 eligible Soldiers, from a BCT of a previously used data collection survey was used.16–19 All containing approximately 3,500 Soldiers, volunteered to data were self-reports and all except history of LBP (yes/no), participate in this study. Of these, 805 filled out the post- seen by a medical provider (yes/no), and sex (M/F) were free deployment survey. Of the 389 participants lost to follow text. Data was collected on age; sex; Army Physical Fitness up, 9 were killed in action, 55 were medically evacuated (43 Test (APFT) score (most recent score in the 6 months before for illness and 8 for injury [2 for LBP]), and the remaining deployment); hours per week spent on cardiovascular train- 325 did not return with the main unit for unspecified reasons ing, core training, and strength training; and history of LBP. that were nonmedical in nature (Fig. 1). The Soldiers were then deployed for 12 months. Within 1 week of returning to the United States from Afghanistan, Soldiers completed the postdeployment questionnaire as a station during their reintegration process. The 805 Soldiers provided data on the hours per day or week spent conducting various occupational tasks performed while deployed. Tasks were wearing body armor, lifting objects weighing more than 30 lb (not including or in addition to body armor), dismounted patrolling, riding in tactical vehicles, and desk work.