Alexandria Journal of Anesthesia and Intensive Care 3

PROGNOSTIC VALIDITY AND RELIABILITY OF THE SOFA SCORE IN MULTIPLE TRAUMA PATIENTS

Ahmed S. Okasha, M.D.*, Ayman S.H. Rofaeel, M.D.§, Said M. El-Medany, M.D.* Sameh M. Shaker, MB. BCh.# *Department of Anesthesia and Critical Care , Faculty of Medicine, Alexandria University. §Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Mansoura University. #Department of Critical Care, Emergency Hospital, Mansoura University.

ABSTRACT Background: This study evaluated the reliability of the SOFA score in prediction of outcome in multiple traumatized patients. Methods: 44 multiple traumatized patients admitted to surgical ICU were prospectively enrolled. The SOFA score was evaluated daily throughout the first seven days of ICU stay and at ICU discharge, whereas the total maximum SOFA score was recorded as the worst of all daily recorded scores. Glasgow Outcome Scale (GOS) was used to assess outcome at time of ICU discharge. The quality of outcome was categorized as survival with either good outcome (good recovery and moderate disability) or poor outcome (severe disability and vegetative state), and non-survival. All recorded scores were analyzed in relation with both GOS and quality of outcome. Results: No significant correlation was found between SOFA score at the first and second days of ICU stay with either GOS or the quality of outcome. The correlation between SOFA score with GOS and quality of outcome exhibited the earliest significance at the third day (P <0.05), and then showed a trend of progressive improvement with subsequent daily scores till became maximum at the seventh day, at ICU discharge, and for the total maximum SOFA score. At the third day of ICU stay, survival was associated with median SOFA score of 5 for good outcome, and 7 for poor outcome, whereas, non-survival was associated with median SOFA score of 9. Conclusion: The SOFA score provides valid and reliable prognostic information in multiple trauma patients. While the best prognostic capability was achieved for the SOFA score at the seventh day of ICU stay, at ICU discharge, and for the total maximum SOFA score, SOFA score at the third day exhibited the earliest reliable outcome prediction with efficient discrimination among survivors with good outcome or poor outcome versus non-survivors.

INTRODUCTION SOFA score, as an /failure Multiple trauma victims are exposed to a assessment score, in prediction of outcome in potential risk for developing multiple organ multiple traumatized critically ill patients through dysfunction and/or failure, which represent major daily evaluation during ICU stay. Also, the study causes of morbidity and mortality in these aimed to evaluate the ability of SOFA score to patients(1,2). Organ dysfunction after multiple trauma discriminate among different qualitative categories is a process rather than an event, hence it should be of outcome of multiple traumatized patients; mainly seen as a continuum and should not be described the quality of survival versus non-survival. simply as present or absent. The time factor is fundamental as the development of organ failure PATIENTS AND METHODS may take some time(3). This prospective study included forty four The Sequential Organ Failure Assessment multiple injured patients, 18 to 65 years old, who (SOFA) score has been applied to improve the were admitted to the surgical understanding of the pathogenesis of organ (ICU) at the Emergency Hospital, Mansoura dysfunction/failure and the inter-relation between University. The study protocol was approved by the failure of various organs(4). Since mortality is institutional research and ethics committee and an directly related to the degree of organ dysfunction(5), informed consent was secured from the patient’s we hypothesized that the SOFA score could provide next of kin. Patients with preexisting systemic reliable prognostic information in multiple disease of clinical significance and those with a traumatized patients, and hence, it may aid the length of ICU stay less than 2 days were excluded. judgment of patient’s quality of outcome. Also, as Standard ICU was applied, the SOFA score is designed for sequential including continuous electrocardiogram, non- assessment of the dynamic course of organ invasive , oxygen saturation, end tidal dysfunction, the collection of data on daily basis carbon dioxide tension, temperature, central venous may adequately reflects the progression of organ pressure, and urine output. Patients' management dysfunction/failure during a complex clinical course followed a standard protocol for management of in the intensive care unit (ICU). This study was head injury, whereas associated systemic injuries designed to test the validity and reliability of the were managed through appropriate consultation of

AJAIC-Vol. (7). No. 2. September 2004 Alexandria Journal of Anesthesia and Intensive Care 4 the corresponding surgical specialties. Hemo- disability (MD), severe disability (SD), persistent dynamicaly unstable patients were managed with vegetative state (PVS), and death] were categorized increasing the rate of intravenous fluid into three qualitative outcome categories. Outcome administration, followed by continuous infusion of was classified as survival and non-survival (death). vasoactive drugs (, , or The quality of survival was further categorized into epinephrine) according to a pre-adjusted infusion either good outcome (GR and MD) or poor outcome rate. (SD and PVS). All daily recorded SOFA scores Evaluation of organ dysfunction was performed were analyzed in relation to GOS and the quality of according to the set of clinical (respiratory support, outcome. mean arterial blood pressure, Glasgow Scale and urine output) and laboratory (arterial blood gas STATISTICAL ANALYSIS analysis, platelets count, bilirubin concentration, Data were analyzed with Statistical Package for serum creatinine) parameters of the SOFA score. Social Sciences program (SPSS, version 10), and The most abnormal value for each parameter in were presented as median (SD), or as indicated every 24 hours period was recorded, and the total elsewhere. Spearman Rank Correlation Analysis score was interpreted as shown in table 1(4,6). The was used to test the relationship between daily SOFA score was recorded at ICU admission (first SOFA scores with GOS, and with the quality of day), then daily throughout the first seven days of outcome. For the purpose of analysis, GOS was ICU stay, and at time of ICU discharge. The total ranked as 5 to 1 for GR to death, respectively. maximum SOFA score was recorded as the worst Pearson Chi-square test was used to test the degree score of all daily recorded SOFA scores throughout of conditional distribution/response of qualitative the whole period of the study. For every organ variables; the distribution of values of the quality of system, organ dysfunction was defined as SOFA outcome (as the dependent variable) across different score of 1-2, meanwhile organ failure was defined values of all recorded SOFA scores (as the as SOFA score of 3-4. independent variable). A probability (P) value was Glasgow Outcome Scale (GOS) was used considered to be statistically significant if < 0.05, to assess outcome at time of ICU discharge. For the and highly significant if < 0.01. purpose of assessing the quality of outcome, the five components of GOS [good recovery (GR), moderate

Table (1): The Sequential Organ Failure Assessment (SOFA) score(4,6). SOFA score 0 1 2 3 4

≤ 200 ≤ 100 Respiration > 400 ≤ 400 ≤ 300 with respiratory with respiratory PaO /FiO (mmHg) 2 2 support support

Coagulation Platelets (×103/mm3) > 150 ≤ 150 ≤ 100 ≤ 50 ≤ 20

Liver Bilirubin (mg/dl) < 1.2 1.2 – 1.9 2.0 – 5.9 6.0 – 11.9 > 12.0 (µmol/l) (< 20) (20-32) (33-101) (102-204) (>204)

Dopamine > 5 or Dopamine > 15 or Dopamine ≤ 5 Cardiovascular No MAP < 70 epinephrine ≤ 0.1 epinephrine > 0.1 or or dobutamine hypotension mmHg or norepinephrine > (any dose)* ≤ 0.1* 0.1*

Central nervous system 15 13 – 14 10 – 12 6 – 9 < 6 Glasgow Coma Score

Renal Creatinine (mg/dl) < 1.2 1.2 – 1.9 2.0 – 3.4 3.5 – 4.9 > 5 (µmol/l) (< 110) (110-170) (171-299) (300-440) (> 440)

or urine output or < 500 ml/day or < 200 ml/day *Adrenergic agents administered for at least 1 hour (doses given are in µg/kg/min). MAP; mean arterial pressure.

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RESULTS <0.05; table 4). Survival was associated with Patients' characteristics and the duration of ICU median SOFA score of 5 for good outcome, and 7 stay are displayed in table 2. All patients sustained for poor outcome, whereas, non-survival was trauma to the head plus one or more of other associated with median SOFA score of 9 (figure 1). anatomical sites/systems (chest, abdomen or The best correlation with outcome was orthopedic trauma). Patients were distributed achieved with SOFA score at the seventh day of according to their outcome at ICU discharge (GOS ICU stay, at discharge, and with the total maximum and quality of outcome; table 3). No significant SOFA score (P <0.01; table 4). For both the SOFA correlation was found between SOFA score score at the seventh day and at discharge, good evaluation over the first and second days of ICU outcome was associated with a median value of 2, stay, with either GOS or the quality of outcome poor outcome was associated with median value of (table 4). The correlations between SOFA scores at 7 and 5 respectively, whereas, non-survival was subsequent days of follow up with GOS and the associated with a median value of 11 and 12 quality of outcome were significant (P <0.05; table respectively (figure 1). For the total maximum 4), and showed a trend of progressive improvement SOFA score, survival was associated with median starting from the third day through SOFA score at SOFA score of 7 for good outcome, and 11 for poor discharge. outcome, whereas, the median SOFA score SOFA score at the third day was the earliest associated with non-survival was 12 (figure 1). significant predictor of the quality of outcome (P

Table (2): Patients characteristics. median ± SD range Age (years) 34 ± 11 18 – 65 Initial GCS score 8 ± 3 3 – 14 Initial SOFA score 7 ± 3 2 – 12 Total duration of ICU stay 20 ± 8 8 – 47 N (%) Gender Male 33 (75%) Female 11 (25%) Extent of trauma 2 sites/systems 8 (18.2%) 3 sites/ systems 32 (72.7%) 4 sites/ systems 4 (9.1%) Data are presented as median ± SD or number (n) and percent (%).

Table (3) Distribution of patients according to Glasgow Outcome Scale (GOS) and the quality of outcome. GOS Quality of outcome Good recovery 10 (22.7%) Survival Moderate disability 10 (22.7%) Good outcome 20 (45.4%) Severe disability 2 (4.55%) Persistent vegetative state 3 (6.85%) Poor outcome 5 (11.4%) Death 19 (43.2%) Non-survival 19 (43.2%) Data are presented as number and percent (%).

Table (4): Serial SOFA scores in correlation with Glasgow Outcome Scale (GOS), and the quality of outcome. GOS Quality of outcome r value P value r value P value SOFA 1 0.024 N.S. 0.052 N.S. SOFA 2 0.240 N.S. 0.363 N.S. SOFA 3 0.536 < 0.05 0.646 < 0.05 SOFA 4 0.564 < 0.05 0.605 < 0.05 SOFA 5 0.638 < 0.05 0.779 < 0.05 SOFA 6 0.760 < 0.05 0.850 < 0.05 SOFA 7 0.871 < 0.01 0.873 < 0.01 SOFA-D 0.895 < 0.01 0.902 < 0.01 SOFA-M 0.810 < 0.01 0.796 < 0.01 SOFA 1-7; SOFA score at the first through the seventh days of ICU stay respectively. SOFA-D; SOFA score at ICU discharge, SOFA-M; total maximum SOFA score. r value = correlation coefficient between daily SOFA scores and GOS/quality of outcome. P value >0.05 = non-significant (N.S.), <0.05 = significant, <0.01 = highly significant.

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20 Good outcome 18 Poor outcome 16 Nons urvival

14

12

10

SOFA score 8

6

4

2

0 SOFA 1 SOFA 2 SOFA 3 SOFA 4 SOFA 5 SOFA 6 SOFA 7 SOFA D SOFA M Figure 1. Trend of daily SOFA scores in relation to the quality of outome

SOFA 1-7; SOFA score at the first through the seventh days of ICU stay respectively SOFA D; SOFA score at discharge SOFA M; total maximum SOFA score

DISCUSSION failure and death, and thus between morbidity and The present study demonstrated that the SOFA mortality. Unlike most available scoring systems, score represents a reliable outcome prediction model the SOFA score has been applied to focus on in multiple traumatized patients. Since all patients in morbidity (4). our study sustained head trauma, which is In order to extend the reliability of the considered a major contributor in predicting SOFA score, not merely as a descriptive score but as outcome in multiply injured patients (7), outcome a prognostic one as well, the quality of outcome was assessed by the Glasgow Outcome Scale after multiple trauma has received major (GOS); a specific model for detection of outcome consideration in our study. The prognostic validity after brain injury (8). The persistent correlation of SOFA scores at the first (admission) and second between daily SOFA scores and GOS in our study days of ICU stay were not evident in the current represents a novel approach in prediction of study. Only SOFA score at the third day was the outcome in multiple traumatized patients, which earliest reliable predictor of outcome, whereas the would improve the appreciation and extend the best prediction of outcome was achieved by SOFA validation of the prognostic capability of the SOFA score at the seventh day, at discharge and by the score to include those patients with head injury. total maximum SOFA score. Besides non-survival, Previous studies have used several outcome end SOFA scores starting from the third day of ICU stay points rather than the GOS. When mortality was exhibited a predictive discrimination between considered the sole outcome measure, the SOFA patients who survived with good outcome and those score has been described as a reliable prediction who survived with poor outcome. Non-survivors model for mortality risk in diverse categories of had the highest scores, whereas survivors with good critically ill patients (9-14). This demonstrates outcome had the lowest scores that followed a stable an agreement with the reliable prediction of non- course and survivors with poor outcome had survival by the SOFA score in the present study. intermediary scores. The importance of the analysis of In agreement with our study, the SOFA morbidity is increasingly recognizable, since score on admission was reported to exhibit no mortality alone is considered insufficient for predictive differentiation between survival and non- assessing ICU outcome, as functional health and survival. Prognosis may be better estimated some quality of life cannot be ignored (15-17). Despite time after ICU admission, and an increase in SOFA the primary aim of the SOFA score was not to score over the first three days of ICU stay was predict outcome but to determine the degree of reported to predict mortality better than the (19-21) organ dysfunction, an increase in the mortality rate admission score . Unlike survivors, non- is associated with a greater SOFA score for each survivors tend to exhibit significant increase in (4,18,22,23) organ (18). A relationship exists between organ score over time . This is not unexpected, as

AJAIC-Vol. (7). No. 2. September 2004 Alexandria Journal of Anesthesia and Intensive Care 7 organ dysfunction and hence, the SOFA score, may Moreover, the power and utility of the SOFA score peak after admission. So, the sensitivity of SOFA in trauma patients are supported by the use of the score as a measure for cumulative organ dysfunction , which represents a sensitive and progression of multiple organ index for assessment of the neurologic status of dysfunction/failure seems to be improved with brain trauma patients (36). repeated daily follow up than with the admission The SOFA score remains a gross score (24,25). This is particularly more evident in evaluation, but this is the best way to keep it simple patients with prolonged ICU stays, as the course of and widely applicable. Using more sophisticated ICU stay is unpredictable and can negatively parameters may restrict its use to centers where such influence the performance of the admission score tests are routinely used, or may result in missing (4). data (4). The simplicity of the SOFA score allows Furthermore, strategies directed at the rapid bedside calculation, hence its repeated prevention and/or limiting of further organ assessment can be considered as an easy task (21). dysfunction will have a significant impact on The SOFA score also reflects the utilization of prognosis, independent of the patient condition on therapeutic resources use during ICU stay. Organ ICU admission (26). Therefore, the SOFA score failure prolongs the length of ICU stay and involves functions as an index for determining either increased use of resources, so assessment of sequential deterioration or improvement of the morbidity is vital for the cost-effective analysis of pathological condition during treatment (18,27,28). therapeutic interventions (4,37). Early categorization of patients according In conclusion, the SOFA score appeared to to their expected outcome represents a major provide valid and reliable descriptive and prognostic challenge; hence early prediction of outcome was information in multiple trauma patients, as it reflects considered another important target of application of the progression of multiple organ dysfunction/ the SOFA score in our patients' population. failure in relation to prognosis of these victims. Although SOFA scores at the seventh day of ICU While the best prognostic capability was achieved stay and at discharge were the strongest predictors by the SOFA score at the seventh day, at ICU of outcome, it seems clinically not feasible to wait discharge, and the total maximum SOFA score, the for the whole first week to be able to judge the SOFA score at the third day of ICU stay was the patient’s outcome, while such prediction can be earliest reliable outcome predictor. The SOFA score possible at the third day. demonstrated good correlation with outcome Similarly, the total maximum SOFA score assessed by GOS at ICU discharge, and also, has been reported as a very reliable predictor of provided efficient discrimination among different outcome (10,19,29,30), which is still valid in our qualitative outcome categories; survival with good study. In the current study, with a total maximum or poor outcome versus non-survival. As an easily SOFA score of 12 or higher, mortality rate was applicable scoring system, the routine application of 100%. This finding is in close similarity with the SOFA score in follow-up and outcome previous studies which described best sensitivity prediction in multiple traumatized patients starting and specificity for prediction of mortality with a cut- from the third day of ICU stay seems to be off value ranging from 12-15 for the total maximum advisable. SOFA score (4,18,19). However, since multiple trauma follows a dynamic course, it is unexpected to REFERENCES determine when the maximum SOFA score will be 1- Fry DE, Pearlstein L, Fulton RL, Polk HC: encountered, or the patient's score will be followed Multiple system organ failure. The role of indefinitely. So, when an early prediction is uncontrolled infection. 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