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The impact of BMI on polytrauma outcome
Injury, Int. J. Care Injured 43 (2012) 184–188
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
The impact of BMI on polytrauma outcome Michael Hoffmann a,*, Rolf Lefering b, Michaela Gruber-Rathmann a, Johannes Maria Rueger a, Wolfgang Lehmann a Trauma Registry of the German Society for Trauma Surgery a
Department of Trauma, Hand- and Reconstructive Surgery, University Hospital Hamburg Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany Institute for Research in Operative Medicine (IFOM), University of Witten/Herdecke, Cologne-Merheim Medical Center (CMMC), Ostmerheimerstrasse 200, D-51109 Cologne, Germany b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 25 May 2011
Background: Varying results have been reported concerning the effect of body mass index (BMI) on polytrauma outcome. Although most studies focus on obesity and its associated preexisting medical diseases as a predictor for increased mortality rates, there is evidence that polytrauma patients with underweight also face an inferior outcome. Methods: Records of 5766 trauma patients (minimum 18 years of age, Injury Severity Score 16, treated from 2004 to 2008) documented in the Trauma Registry of the German Society for Trauma Surgery were subclassified into 4 BMI groups and analysed to assess the impact of BMI on polytrauma outcome. Results: Underweight (BMI Group I) as well as obesity (BMI Group IV) in polytraumatized patients are associated with significantly increased mortality by multivariate logistic regression analysis with hospital mortality as the target variable (adjusted odds ratio for BMI Group I, 2.1 (95% CI 1.2–3.8, p = 0.015); for BMI Group IV, 1.6 (95% CI 1.1–2.3, p = 0.009)). Simple overweight (BMI Group III) does not qualify as a predictor for increased mortality (odds ratio 1.0; 95% CI 0.8–1.3). Conclusions: There is a significant correlation between obesity, underweight, and increased mortality in polytraumatized patients. Efforts to promote optimal body weight may reduce not only the risk of chronic diseases but also the risk of polytrauma mortality amongst obese and underweight individuals. ß 2011 Elsevier Ltd. All rights reserved.
Keywords: BMI Polytrauma Obesity Underweight Outcome Trauma Injuries Registry
Introduction Varying results have been reported concerning the effect of body mass index (BMI) on polytrauma outcome.1,2 Although most studies focus on obesity with its associated preexisting medical diseases as a predictor for increased mortality rates, there is evidence that polytrauma patients with underweight also face an inferior outcome. BMI is an anthropometric index of weight-forheight and is defined as the weight in kilograms divided by the square of the height in metres (kg/m2). Despite some contradictory results,3 population studies have demonstrated U-shaped curves relating BMI to mortality,4,5 suggesting increased mortality at both extremes of body weight.6 Normal weight individuals have a BMI of 18.5–24.9 kg/m2. BMI is commonly used to classify underweight (BMI < 18.5 kg/m2), overweight (BMI 25 kg/m2), and obesity (BMI 30 kg/m2) in adults. BMI values are age-independent and the same for both sexes.7 Obesity is widely acknowledged to be a
* Corresponding author. Tel.: +49 040 7410 53459; fax: +49 040 7410 54569. E-mail addresses: [email protected], [email protected] (M. Hoffmann). 0020–1383/$ – see front matter ß 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2011.05.029
leading public health threat. Its impacts include higher risks of cancer, diabetes mellitus, hyperlipidemia, heart disease, hypertension, insulin resistance, arthritis, and death.8 Whereas the association between obesity and these chronic conditions is clear, there remains considerable debate regarding the effect of obesity on outcomes in critical care and trauma settings.1,9 Obesity also affects patient management in pre- and in-hospital trauma care. It makes airway management more challenging, surgical exposures more difficult, and radiographic imaging less reliable.10 Data concerning the outcome of underweight polytraumatized patients is limited. Studies focusing on the relationship between bodyweight and mortality describe a U-shaped relationship revealing increased mortality in both underweight and obese patients.5 The reported impact of BMI on outcomes in critical care patients shows increased mortality in underweight patients but not in overweight, obese, or severely obese patients. In a univariate analysis according to type of admission, increased mortality was seen in underweight patients in the medical and emergent surgical groups, but not in the elective surgical group.6 Conflicting results have been reported concerning the association between bodyweight and polytrauma outcome. Critical care patients that are overweight, obese, and severely obese reportedly face to some extent decreased mortality
M. Hoffmann et al. / Injury, Int. J. Care Injured 43 (2012) 184–188
and improved functional status at hospital discharge.6 Whilst this seems to contradict data from population-based studies3,5 and disease specific studies,11,12 as well as general assumptions in the critical care literature,13,14 it is consistent with prior data from hospitalized patients.14,15 In blunt trauma victims, severely obese patients were characterized by rapid deterioration and demise that was unresponsive to intervention. Further studies characterize obesity as an independent risk factor of mortality in severely injured blunt trauma patients1 and report an increased risk of organ failure after severe trauma.17 Concerning the impact on outcome of polytraumatized patients, there are several studies characterizing BMI as a predictor for injury patterns, reporting that blunt trauma patients with a BMI > 31 have a substantially greater incidence of pulmonary complications and mortality.15 Boulanger et al.18 reported that patients with a high BMI were more likely to suffer rib fractures, pulmonary contusion and pelvic fractures and were less likely to have head and abdominal injury. There are studies showing higher postoperative complication rates in underweight patients due to the obesity paradox and low functional reserves in this group.6,16 Although there is no data available qualifying underweight as a predictor for inferior polytrauma outcome, we hypothesized that both obesity and underweight are associated with increased mortality and worse outcome in critically injured trauma patients. The objective of this study is to characterize the relationship between BMI and polytrauma outcome. We used the Trauma Registry of the German Society for Trauma Surgery to investigate the prognostic value of BMI in this setting.
185
Patients were allocated into four groups according to body mass index: Group I – BMI < 20.0 (underweight), Group II – BMI 20.0– 24.9 (normal weight), Group III – BMI 25.0–29.9 (overweight), and Group IV – BMI 30 (obesity). Since injury pattern and severity might be different in the BMI subgroups the observed outcome was compared with a prognostic estimate derived from the RISC score.19 This score was developed and validated in the TR-DGU. It considers age, new ISS, head injury, Glasgow Coma Scale, base excess, coagulation, indirect signs of severe bleeding, and cardiac arrest for prognosis. The RISC prognosis reflects the average expected hospital mortality rate in the TR-DGU for the period from 1993 until 2000.19 Statistical analysis Data are presented as mean standard deviation (SD) for continuous variables and as percentages for categorical variables. Data were compared across the four BMI groups using the x2-test for categorical variables and analysis of variance (ANOVA) for continuous variables. A pairwise comparison of BMI subgroups was not performed due to the problem of multiple testing with an increased risk of type one error. A p-value < 0.05 was considered significant. Kaplan–Meier survival plot was used to present time-to-death data. To assess the impact of BMI on outcome a multivariate logistic regression analysis was performed with hospital mortality as target variable, and RISC score plus BMI group as potential predictors. Odds ratios (ORs) with 95% confidence intervals are reported. Data were analysed with SPSS statistical software (SPSS Version 15.0, Chicago, IL, USA). Results
Methods The Trauma Registry of the German society for Trauma Surgery (TRDGU) The TR-DGU was founded in 1993 to collect anonymous multicenter datasets from multiple trauma patients on a voluntary basis. As of 2008 data from 42,248 trauma patients was included in the registry. The documentation is structured in four consecutive time phases after trauma: A, pre-hospital phase; B, emergency room and initial therapy until intensive care unit (ICU) admission; C, ICU; D, discharge including list of injuries, procedures, and outcome. The criteria for inclusion are alive on admission to hospital plus the potential need for intensive care treatment. Data are submitted to a central password-protected database server. Data anonymity is guaranteed for the patients and participating trauma centres. The registry records epidemiological, physiological, laboratory, diagnostic, operative, interventional, and intensive care medical data. Several injury severity and prognostic scores are derived from the data. Patients who died at the scene or are dead on emergency room arrival are excluded, as are patients with minor injuries and burns. In 2002, TR-DGU has introduced an online documentation system. Currently, 145 hospitals are affiliated with the TR-DGU (www.traumaregister.de).
A total of 5766 patients met the inclusion criteria. The overall mean body mass index (BMI) was 25.8 4.5 (range 13.8–67.9). The female to male ratio was approximately 1:3, which is typical for an unselected trauma collective. However, females were much more common in the underweight group (59.1%, Fig. 1). Compared to their normal weight counterparts, underweight patients were on average 5 years younger. Overweight and obese patients were approximately 10 years older (p < 0.001). There was significant difference concerning suicide rates, affecting mainly the underweight group (13.0%). The suicide rate in females was approximately twice as high as in males in all BMI subgroups. Suicide rates thus varied from 2.0% in obese males to 16% in underweight females. There was no significant difference between all BMI groups concerning psychiatric disorders (p = 0.068). Drug and alcohol abuse showed a significant decreasing rate with
Study population Weight and height have been recorded since 2005. Adult patients were eligible for the present investigation if the injury occurred between 2005 and 2008, and if the documentation was complete regarding demographics, injury pattern, outcome, and prognostic factors necessary to derive the prognostic RISC score,19 which calculates an outcome prognosis for polytraumatized patients. Exclusion criteria were age < 16 and Injury Severity Score (ISS) < 9.
Fig. 1. The female to male ratio was approximately 1:3, which is typical for an unselected trauma collective. However, females were much more common in the underweight group, whereas males were predominantly represented in the other subgroups.
M. Hoffmann et al. / Injury, Int. J. Care Injured 43 (2012) 184–188
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Table 1 Basic characteristics, injury pattern, and treatment according to BMI subgroup.
Number of patients Male gender Age Injury Severity Score (ISS) Relevanta head injury Relevanta thoracic injury Relevanta abdominal injury Relevanta extremity injury Suicide Hypertension Arrhythmia Coronary heart disease COPD/asthma Diabetes Psychiatric disorders Drugs and alcohol abuse Penetrating trauma Blunt trauma Road traffic accident Prehospital CPR Catecholamines therapy Preclinical intubation Sedation Chest drain placement Blood transfusion Admitted to ICU
Group I underweight
Group II normal
Group III overweight
Group IV obese
All patients
p-Value
269 40.9% 34 19 24 13 38% 51% 25% 52% 13.0% 2.4% 0% 3.2% 5.6% 1.2% 3.6% 13.2% 3.3% 96.7% 61% 0% 2% 40% 82% 3% 25% 96%
2617 74.5% 39 19 27 14 46% 58% 22% 45% 6.5% 3.5% 0.7% 2.7% 3.0% 0.5% 2.9% 7.7% 4.3% 95.7% 65.1% 2.3% 7% 52% 82% 6% 27% 95%
2120 80.8% 48 18 26 13 44% 55% 18% 44% 6.1% 7.7% 1.6% 6.4% 3.6% 1.1% 3.0% 8.6% 4.6% 95.4% 59.2% 2.0% 8% 49% 82% 6% 28% 95%
760 77.6% 49 17 26 12 36% 64% 18% 47% 2.6% 12.0% 2.3% 9.6% 7.0% 0.7% 1.3% 6.4% 3.4% 96.6% 66.6% 1.3% 6% 45% 82% 7% 26% 96%
5766 75.7% 44 19 26 13 44% 58% 20% 45% 6.2% 6.1% 1.2% 5% 3.9% 0.8% 2.8% 8.1% 4.2% 95.8% 62.9% 1.9% 7% 49% 82% 6% 27% 95%
<0.001 <0.001 <0.001 <0.001 <0.001 0.001 0.085 <0.001 <0.001 0.001 <0.001 <0.001 0.068 0.068 0.006 0.466 0.466 <0.001 0.056 0.015 0.001 0.99 0.13 0.60 0.89
The BMI groups show significant differences concerning the relevant injuries leading to polytrauma. Suicide rates affect approximately twice as often the underweight group, whereas catecholamine therapy is least required in this subgroup. a AIS severity 3.
decreasing BMI (p = 0.006). Overall injury severity (ISS) was similar, with an average intergroup difference of about 3 points. There was, however, variation in predominant injury pattern. Head injury was less frequent in the underweight and obese BMI groups, whilst abdominal injuries had the highest prevalence rates in the underweight group. Catecholamine treatment was used less frequently in BMI Group I (2.2%) as compared to all other groups (about 7%). We found the lowest rate of prehospital intubation in the underweight group (39.6%). There was no significant difference concerning blood transfusion rates between BMI groups. There was also no significant difference regarding chest drain placement rates (p = 0.13), sedation (p = 0.98), prehospital resuscitation (p = 0.056), and intensive care unit admission (Table 1). Outcome Multiple organ failure and sepsis were significantly associated with BMI, where obese patients had approximately twice as many complications compared to underweight patients (Table 2).
The duration of in-hospital treatment, length of ICU stay, and duration of mechanical ventilation consistently increased with BMI. All differences were statistically significant (Table 2). Regarding hospital outcome there was a slight increase in mortality with higher BMI, but these differences were not significant (p = 0.76 (Table 2)). Conversely, the mortality rate within the first 24 h seemed to decrease nonsignificantly with increasing BMI, from 3.0% in BMI Group I to 2.2% in BMI Group IV (p = 0.77). Also there was an almost significant difference concerning prehospital CPR performed on 0% of the underweight patients (p = 0.056) compared to the normal (2.3%), overweight (2.0%) and obese (1.3%) patient groups. Since injury severity and injury pattern varied within the BMI groups, adjustment of outcome had to be considered. The difference between observed and expected outcome based on the RISC score was lowest in the underweight group. In multivariate analysis both underweight (BMI Group I) as well as obesity (BMI Group IV) show significant prognostic relevance for polytrauma outcome (odds ratio = 2.1 (BMI Group I), odds ratio = 1.6 (BMI Group IV) (Table 3). A BMI
Table 2 Outcome according to BMI subgroup.
Number of patients Death within the first 24 h Hospital mortality RISC mortality prognosis Multiple organ failure (MOF) Sepsis Duration of intubation (days) ICU stay (days) Hospital stay (days) Ventilator-free days (30 days) Time to death (days)
Group I underweight
Group II normal
Group III overweight
Group IV obese
All patients
p-Value
269 8 (3.0%) 21 (7.8%) 9.7% 11 (13.8%) 14 (5.3%) 3.7 7.8 23.6 24.5 5.7
2617 77 (2.9%) 202 (7.7%) 14.8% 183 (23.5%) 237 (9.6%) 6.5 10.7 26.8 22.1 10.1
2120 61 (2.9%) 176 (8.3%) 15.8% 158 (24.6%) 191 (9.5%) 6.8 11.2 28.0 21.9 16.6
760 17 (2.2%) 67 (8.8%) 13.2% 59 (30.3%) 81 (11.2%) 8.2 12.7 30.5 21.2 16.6
5766 163 (2.8%) 466 (8.1%) 14.7% 411 (24.2%) 523 (9.6%) 6.7 11.0 27.6 22.0 13.9
0.77 0.76 <0.001 0.031 0.053 <0.001 <0.001 <0.001 <0.001 <0.001
Multiple organ failure and sepsis were significantly associated with BMI, where obese patients had approximately twice as many complications compared to underweight patients. The duration of in-hospital treatment, length of ICU stay, and duration of mechanical ventilation consistently increased with BMI.
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Table 3 Result of multivariate analysis with BMI group and RISC score as predictors of hospital outcome (Group II used as reference group). Group BMI (reference BMI Group II) BMI Group I (underweight) BMI Group III (overweight) BMI Group IV (obese) RISC score Constant
Regression coefficient 0.733 0.003 0.472 0.919 1.250
p-Value
Odds ratio (OR)
95% confidence interval for OR
0.015 0.981 0.009 <0.001 <0.001
2.08 0.99 1.60 2.51 –
1.15–3.77 0.76–1.29 1.13–2.28 2.34–2.68 –
Underweight (BMI Group I) as well as obesity (BMI Group IV) in polytraumatized patients are associated with significantly increased mortality by multivariate logistic regression analysis with hospital mortality as the target variable. Overweight (BMI Group III) is not an indicator of higher mortality and has the same outcome as normal weight patients (BMI Group II).
between 25 and 30 (BMI Group III) was not associated with prognostic relevance. Regarding long-term outcome the Kaplan– Meier survival plot with cumulated survival curves showed a correlation between increased BMI and increased late mortality rates (Fig. 2). Discussion The present study was designed to investigate the effect of BMI on mortality risk and outcome in trauma patients, identifying specific time points of potential pitfalls in trauma care. An understanding of both obesity and underweight related complications is vital to those involved in trauma care. The prevalence of obesity is a rapidly growing problem in industrialized countries. The increasing rate of obese patients threatens to alter current medical and surgical practice.27 Obese patients are more likely to have substantial medical comorbidities and are at increased risk of postsurgical and posttraumatic complications.17,20 The study data confirms significant differences concerning the prevalence of hypertension, coronary heart disease, arrhythmia and chronic obstructive lung diseases in overweight and obese patients. Although there was no significant difference concerning the prevalence of diabetes. Our study demonstrates that obesity is significantly associated with increased mortality in polytraumatized patients. Although the population of trauma victims does not necessarily mirror the national population as a whole, the general trend towards increased obesity across age groups and gender can be expected
Fig. 2. Concerning long-term outcome the Kaplan–Meier survival plot with cumulated survival curves shows that elevated BMI is associated with late mortality.
to shift the population of injured patients as well.17 Thus the identification of critical time care windows is mandatory for modern trauma care. Our study shows that obesity is associated with multiorgan failure (MOF) and sepsis mortality in the longterm time whereas underweight is associated with an increased mortality rate in the first 24 h. In this retrospective analysis we found that obese and underweight patients have some minor differences regarding the mechanism of injury and injury patterns but show significant higher mortality rates than normal weight patients, especially when adjusted for admission status. In our study 0% of the underweight patients underwent prehospital CPR. Accounting the fact, that patients dead on hospital arrival or accident scene are not included into the Trauma Registry Database, might contribute to the feeling that these patients have an even higher 24 h mortality after trauma than can be proved with our data. Brown et al. found that obese patients had a higher incidence of chest injury and lower extremity fractures. Nevertheless they face a lower incidence of head injury.21 Arabi et al.22 also reported a higher frequency of lower extremity fractures, but a lower frequency of abdominal injuries, invoking the ‘‘cushion effect’’ of the obese abdomen protecting the abdominal viscera from injury. In our study we found a similar overall Injury Severity Score (ISS) between all BMI groups, with an average difference of about 3 points. There is, however, variation in the injury pattern. Head injury was less frequent in the underweight and obese BMI groups, whilst abdominal injury rates were highest in the underweight subgroup. Our study indicates an increased risk of MOF and sepsis in obese patients after trauma compared to normal and underweight patients. A hypothetical explanation for this is that the inflammatory response triggered in severe trauma could have an altered, more fatal manifestation in obese patients. Similar results were found in other studies.1 Smith-Choban et al.15 found that 7 of 8 severely overweight trauma patients died from acute respiratory distress syndrome, an inflammation-mediated event. Other studies documented that the presence of MOF in morbidly obese patients in a medical intensive care unit is the strongest independent predictor of mortality.23 The duration of ICU stay might also contribute to higher mortality. In our study we found that the duration of in-hospital treatment, the length of ICU stay, and duration of mechanical ventilation consistently increased with an increasing BMI. All differences were significant and associated with a significant higher mortality rate in the obese BMI Group IV. Other studies have identified the need for transfusion of packed red blood cells (pRBC) during resuscitation as an independent risk factor for posttraumatic complications and organ dysfunction. In the present study we found no statistical significant relationship between pRBC transfusion rates during resuscitation after adjusting for these factors between underweight, normal weight, overweight, and obesity. This was surprising as we expected higher transfusion rates in the underweight collective due to low functional reserves and a suspected higher impact of equivalent blood loss in trauma. Furthermore this is found to be important for evaluating the effect of obesity and underweight on posttraumatic
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M. Hoffmann et al. / Injury, Int. J. Care Injured 43 (2012) 184–188
complications independent of the effects of blood transfusion. The nature of substantial body mass both in obese and underweight patients has an impact on how health care providers deliver medical care. In our study, we showed that obese patients have a considerably increased duration of ventilator use with concomitant increased pneumonia rates. This might be, in part, because of an intrinsic reduced lung capacity and increased work of breathing. These patients are also at greater risk of aspiration pneumonia.24 Difficulties in maintaining peripheral i.v. lines increase the use of central venous catheters. In critically ill obese patients, the persistent need for venous access is common and promotes the practice of long-term central access. This practice can increase the risk of catheter-associated sepsis, increasing the risk of MOF and sepsis in obese trauma patients. These factors may play a role in delaying early and consequent trauma care. Due to the shift of physical landmarks, underweight as well as obesity can adversely affect efficient trauma health care delivery, preventing health care providers from performing pivotal procedures. Procedures such as endotracheal intubation or tracheostomy are more challenging because of immobility or thickness of subcutaneous tissue of the neck.25 Vascular access in obese patients can also be complicated. Placement of central lines can be difficult because of lack of anatomical landmarks and increased distance to vessels.26 There was a significant intergroup difference concerning intubation rates and use of catecholamines, but we could not detect a significant difference concerning chest drain placement rates. Our study has some limitations. A substantial number of patients had no data regarding height and/or weight and had to be excluded. However, these patients’ characteristics were similar to those of the whole group. Furthermore, the categorization which we chose might have compromised the results. Patients with a BMI of 19 are usually considered as ‘normal’ but we place them in the ‘underweight’ group, mainly because of the limited sample size in this subgroup. Although we have found an association between obesity and trauma mortality, we can only hypothesize concerning the reasons for this association. Due to the retrospective nature of the study, we were not able to account for other medical conditions that may have confounded our results and lead to an increased mortality in this group. Although we found a trend towards higher complication rates in obese patients, we were unable to identify precipitating factors for MOF and sepsis. Conclusion We found that both obesity and underweight are independent risk factors for increased polytrauma mortality and therefore have to be taken into account in polytrauma management. The duration of in-hospital treatment, length of ICU stay, and duration of mechanical ventilation consistently increased with BMI. We also found an increased MOF and sepsis rate in obese patients. This is crucial for adequately allocating intensive care resources in advance. These findings, in conjunction with evidence for an altered inflammatory potential in obese patients, might furthermore lead to potential therapeutic targets to improve outcomes in both obese and underweight patients. The general shift towards a more obese population emphasizes the need for long-term adjustment of medical and financial concepts. The BMI group associated variation of injury pattern should lead to an additional focused assessment of those body parts anticipating injuries to
benefit from early identification. Anticipating BMI group specific critical trauma time care windows is mandatory for effective modern polytrauma management.
Conflict of interest statement There are no conflicts of interest.
References 1. Neville AL, Brown CV, Weng J, et al. Obesity is an independent risk factor of mortality in severely injured blunt trauma patients. Arch Surg 2004;139:983–7. 2. Maheshwari R, Mack CD, Kaufman RP, et al. Severity of injury and outcomes among obese trauma patients with fractures of the femur and tibia: a crash injury research and engineering network study. J Orthop Trauma 2009;23(9):634–9. 3. Manson JE, Stampfer MJ, Hennekens CH, et al. Body weight and longevity: a reassessment. JAMA 1987;257:353–8. 4. Pi-Sunyer FX, Dietz WH, Becker DM, et al. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report. Bethesda, MD: National Heart, Lung, and Blood Institute; 1998. 5. Troiano RP, Frongillo Jr EA, Sobal J, et al. The relationship between bodyweight and mortality: a quantitative analysis of combined information from existing studies. Int J Obes Relat Metab Disord 1996;20:63–75. 6. Tremblay A, Badi V. Impact of body mass index on outcomes following critical care. Chest 2003;123(4):1202–7. 7. Global database on body mass index. WHO; 2004 [accessed 12.12.09]http:// www.who.int/en/. 8. Calle EE, Thun MJ, Petrelli JM, et al. Body-mass index and mortality in a prospective cohort of U.S. adults. N Engl J Med 1999;341:1097–105. 9. Byrnes MC, McDaniel MD, Moore MB, et al. Obesity and increased mortality in blunt trauma. J Trauma 1991;31:1253–7. 10. Boulanger BR, Milzman DP, Rodriguez A. Obes Crit Care Clin 1994;10:613–22. 11. Hoit BD, Gilpin EA, Maisel AA, et al. Influence of obesity on morbidity and mortality after acute myocardial infarction. Am Heart J 1987;114:1334–41. 12. Boulanger BR, Milzman DP, Rodriguez A. Trauma preexisting disease. Part II. Specific management concerns. Crit Care Clin 1994;10:613–22. 13. Marik P, Varon J. The obese patient in the ICU. Chest 1998;113:492–8. 14. Galanos AN, Pieper CF, Kussin PF, et al. Relationship of body mass index to subsequent mortality among seriously ill hospitalized patients. Crit Care Med 1997;25:1962–8. 15. Smith-Choban P, Weireter LJ, Maynes C. Obesity and increased mortality in blunt trauma. J Trauma 1991;31:1253–7. 16. Batsis JA, Huddleston JM, Melton 4th LJ, et al. Body mass index and risk of adverse cardiac events in elderly patients with hip fracture: a population-based study. J Am Geriatr Soc 2009;57(3):419–26. 17. Ciesla DJ, Moore EE, Johnson JL, et al. Obesity increases risk of organ failure after severe trauma. J Am Coll Surg 2006;203(4):539–45. 18. Boulanger BR, Milzman D, Mitchell K, et al. Body habitus as a predictor of injury pattern after blunt trauma. J Trauma 1992;33:228–32. 19. Lefering R. Development and validation of the Revised Injury Severity Classification (RISC) score for severely injured patients. Eur J Trauma Emerg Surg 2009;35:437–47. 20. Pfaffrath T, Wafaisade A, Lefering R, et al. Venous thromboembolism after severe trauma: incidence, risk factors and outcome. Injury 2010;41:97–101. 21. Brown CV, Neville AL, Rhee P, et al. The impact of obesity on the outcomes of 1.153 critically injured blunt trauma patients. J Trauma 2005;59:1048–51. 22. Arabi S, Wahl WL, Hemmila MR, et al. The cushion effect. J Trauma 2003;54:1090–3. 23. El-Solh A, Sikka P, Bozkanat E, et al. Morbid obesity in the medical ICU. Chest 2001;120:1989–97. 24. Williamson JA, Webb RK, Szekely S, et al. The Australian incident monitoring study: difficult intubation: an analysis of 2000 incident reports. Anaesth Intens Care 1993;21:602–7. 25. Koenig SM. Pulmonary complications of obesity. Am J Med Sci 2001;321:249–79. 26. Gilbert TB, Seneff MG, Becker RB. Facilitation of internal jugular venous cannulation using an audio guided Doppler ultrasound vascular access device: results from a prospective, dualcenter, randomized, crossover clinical study. Crit Care Med 1995;23:60–5. 27. Quesenberry Jr CP, Caan B, Jacobsen A. Obesity, health service use, and health care costs among members of a health maintenance organization. Arch Intern Med 1998;158:466–72.
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
The impact of BMI on polytrauma outcome Michael Hoffmann a,*, Rolf Lefering b, Michaela Gruber-Rathmann a, Johannes Maria Rueger a, Wolfgang Lehmann a Trauma Registry of the German Society for Trauma Surgery a
Department of Trauma, Hand- and Reconstructive Surgery, University Hospital Hamburg Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany Institute for Research in Operative Medicine (IFOM), University of Witten/Herdecke, Cologne-Merheim Medical Center (CMMC), Ostmerheimerstrasse 200, D-51109 Cologne, Germany b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 25 May 2011
Background: Varying results have been reported concerning the effect of body mass index (BMI) on polytrauma outcome. Although most studies focus on obesity and its associated preexisting medical diseases as a predictor for increased mortality rates, there is evidence that polytrauma patients with underweight also face an inferior outcome. Methods: Records of 5766 trauma patients (minimum 18 years of age, Injury Severity Score 16, treated from 2004 to 2008) documented in the Trauma Registry of the German Society for Trauma Surgery were subclassified into 4 BMI groups and analysed to assess the impact of BMI on polytrauma outcome. Results: Underweight (BMI Group I) as well as obesity (BMI Group IV) in polytraumatized patients are associated with significantly increased mortality by multivariate logistic regression analysis with hospital mortality as the target variable (adjusted odds ratio for BMI Group I, 2.1 (95% CI 1.2–3.8, p = 0.015); for BMI Group IV, 1.6 (95% CI 1.1–2.3, p = 0.009)). Simple overweight (BMI Group III) does not qualify as a predictor for increased mortality (odds ratio 1.0; 95% CI 0.8–1.3). Conclusions: There is a significant correlation between obesity, underweight, and increased mortality in polytraumatized patients. Efforts to promote optimal body weight may reduce not only the risk of chronic diseases but also the risk of polytrauma mortality amongst obese and underweight individuals. ß 2011 Elsevier Ltd. All rights reserved.
Keywords: BMI Polytrauma Obesity Underweight Outcome Trauma Injuries Registry
Introduction Varying results have been reported concerning the effect of body mass index (BMI) on polytrauma outcome.1,2 Although most studies focus on obesity with its associated preexisting medical diseases as a predictor for increased mortality rates, there is evidence that polytrauma patients with underweight also face an inferior outcome. BMI is an anthropometric index of weight-forheight and is defined as the weight in kilograms divided by the square of the height in metres (kg/m2). Despite some contradictory results,3 population studies have demonstrated U-shaped curves relating BMI to mortality,4,5 suggesting increased mortality at both extremes of body weight.6 Normal weight individuals have a BMI of 18.5–24.9 kg/m2. BMI is commonly used to classify underweight (BMI < 18.5 kg/m2), overweight (BMI 25 kg/m2), and obesity (BMI 30 kg/m2) in adults. BMI values are age-independent and the same for both sexes.7 Obesity is widely acknowledged to be a
* Corresponding author. Tel.: +49 040 7410 53459; fax: +49 040 7410 54569. E-mail addresses: [email protected], [email protected] (M. Hoffmann). 0020–1383/$ – see front matter ß 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2011.05.029
leading public health threat. Its impacts include higher risks of cancer, diabetes mellitus, hyperlipidemia, heart disease, hypertension, insulin resistance, arthritis, and death.8 Whereas the association between obesity and these chronic conditions is clear, there remains considerable debate regarding the effect of obesity on outcomes in critical care and trauma settings.1,9 Obesity also affects patient management in pre- and in-hospital trauma care. It makes airway management more challenging, surgical exposures more difficult, and radiographic imaging less reliable.10 Data concerning the outcome of underweight polytraumatized patients is limited. Studies focusing on the relationship between bodyweight and mortality describe a U-shaped relationship revealing increased mortality in both underweight and obese patients.5 The reported impact of BMI on outcomes in critical care patients shows increased mortality in underweight patients but not in overweight, obese, or severely obese patients. In a univariate analysis according to type of admission, increased mortality was seen in underweight patients in the medical and emergent surgical groups, but not in the elective surgical group.6 Conflicting results have been reported concerning the association between bodyweight and polytrauma outcome. Critical care patients that are overweight, obese, and severely obese reportedly face to some extent decreased mortality
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and improved functional status at hospital discharge.6 Whilst this seems to contradict data from population-based studies3,5 and disease specific studies,11,12 as well as general assumptions in the critical care literature,13,14 it is consistent with prior data from hospitalized patients.14,15 In blunt trauma victims, severely obese patients were characterized by rapid deterioration and demise that was unresponsive to intervention. Further studies characterize obesity as an independent risk factor of mortality in severely injured blunt trauma patients1 and report an increased risk of organ failure after severe trauma.17 Concerning the impact on outcome of polytraumatized patients, there are several studies characterizing BMI as a predictor for injury patterns, reporting that blunt trauma patients with a BMI > 31 have a substantially greater incidence of pulmonary complications and mortality.15 Boulanger et al.18 reported that patients with a high BMI were more likely to suffer rib fractures, pulmonary contusion and pelvic fractures and were less likely to have head and abdominal injury. There are studies showing higher postoperative complication rates in underweight patients due to the obesity paradox and low functional reserves in this group.6,16 Although there is no data available qualifying underweight as a predictor for inferior polytrauma outcome, we hypothesized that both obesity and underweight are associated with increased mortality and worse outcome in critically injured trauma patients. The objective of this study is to characterize the relationship between BMI and polytrauma outcome. We used the Trauma Registry of the German Society for Trauma Surgery to investigate the prognostic value of BMI in this setting.
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Patients were allocated into four groups according to body mass index: Group I – BMI < 20.0 (underweight), Group II – BMI 20.0– 24.9 (normal weight), Group III – BMI 25.0–29.9 (overweight), and Group IV – BMI 30 (obesity). Since injury pattern and severity might be different in the BMI subgroups the observed outcome was compared with a prognostic estimate derived from the RISC score.19 This score was developed and validated in the TR-DGU. It considers age, new ISS, head injury, Glasgow Coma Scale, base excess, coagulation, indirect signs of severe bleeding, and cardiac arrest for prognosis. The RISC prognosis reflects the average expected hospital mortality rate in the TR-DGU for the period from 1993 until 2000.19 Statistical analysis Data are presented as mean standard deviation (SD) for continuous variables and as percentages for categorical variables. Data were compared across the four BMI groups using the x2-test for categorical variables and analysis of variance (ANOVA) for continuous variables. A pairwise comparison of BMI subgroups was not performed due to the problem of multiple testing with an increased risk of type one error. A p-value < 0.05 was considered significant. Kaplan–Meier survival plot was used to present time-to-death data. To assess the impact of BMI on outcome a multivariate logistic regression analysis was performed with hospital mortality as target variable, and RISC score plus BMI group as potential predictors. Odds ratios (ORs) with 95% confidence intervals are reported. Data were analysed with SPSS statistical software (SPSS Version 15.0, Chicago, IL, USA). Results
Methods The Trauma Registry of the German society for Trauma Surgery (TRDGU) The TR-DGU was founded in 1993 to collect anonymous multicenter datasets from multiple trauma patients on a voluntary basis. As of 2008 data from 42,248 trauma patients was included in the registry. The documentation is structured in four consecutive time phases after trauma: A, pre-hospital phase; B, emergency room and initial therapy until intensive care unit (ICU) admission; C, ICU; D, discharge including list of injuries, procedures, and outcome. The criteria for inclusion are alive on admission to hospital plus the potential need for intensive care treatment. Data are submitted to a central password-protected database server. Data anonymity is guaranteed for the patients and participating trauma centres. The registry records epidemiological, physiological, laboratory, diagnostic, operative, interventional, and intensive care medical data. Several injury severity and prognostic scores are derived from the data. Patients who died at the scene or are dead on emergency room arrival are excluded, as are patients with minor injuries and burns. In 2002, TR-DGU has introduced an online documentation system. Currently, 145 hospitals are affiliated with the TR-DGU (www.traumaregister.de).
A total of 5766 patients met the inclusion criteria. The overall mean body mass index (BMI) was 25.8 4.5 (range 13.8–67.9). The female to male ratio was approximately 1:3, which is typical for an unselected trauma collective. However, females were much more common in the underweight group (59.1%, Fig. 1). Compared to their normal weight counterparts, underweight patients were on average 5 years younger. Overweight and obese patients were approximately 10 years older (p < 0.001). There was significant difference concerning suicide rates, affecting mainly the underweight group (13.0%). The suicide rate in females was approximately twice as high as in males in all BMI subgroups. Suicide rates thus varied from 2.0% in obese males to 16% in underweight females. There was no significant difference between all BMI groups concerning psychiatric disorders (p = 0.068). Drug and alcohol abuse showed a significant decreasing rate with
Study population Weight and height have been recorded since 2005. Adult patients were eligible for the present investigation if the injury occurred between 2005 and 2008, and if the documentation was complete regarding demographics, injury pattern, outcome, and prognostic factors necessary to derive the prognostic RISC score,19 which calculates an outcome prognosis for polytraumatized patients. Exclusion criteria were age < 16 and Injury Severity Score (ISS) < 9.
Fig. 1. The female to male ratio was approximately 1:3, which is typical for an unselected trauma collective. However, females were much more common in the underweight group, whereas males were predominantly represented in the other subgroups.
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Table 1 Basic characteristics, injury pattern, and treatment according to BMI subgroup.
Number of patients Male gender Age Injury Severity Score (ISS) Relevanta head injury Relevanta thoracic injury Relevanta abdominal injury Relevanta extremity injury Suicide Hypertension Arrhythmia Coronary heart disease COPD/asthma Diabetes Psychiatric disorders Drugs and alcohol abuse Penetrating trauma Blunt trauma Road traffic accident Prehospital CPR Catecholamines therapy Preclinical intubation Sedation Chest drain placement Blood transfusion Admitted to ICU
Group I underweight
Group II normal
Group III overweight
Group IV obese
All patients
p-Value
269 40.9% 34 19 24 13 38% 51% 25% 52% 13.0% 2.4% 0% 3.2% 5.6% 1.2% 3.6% 13.2% 3.3% 96.7% 61% 0% 2% 40% 82% 3% 25% 96%
2617 74.5% 39 19 27 14 46% 58% 22% 45% 6.5% 3.5% 0.7% 2.7% 3.0% 0.5% 2.9% 7.7% 4.3% 95.7% 65.1% 2.3% 7% 52% 82% 6% 27% 95%
2120 80.8% 48 18 26 13 44% 55% 18% 44% 6.1% 7.7% 1.6% 6.4% 3.6% 1.1% 3.0% 8.6% 4.6% 95.4% 59.2% 2.0% 8% 49% 82% 6% 28% 95%
760 77.6% 49 17 26 12 36% 64% 18% 47% 2.6% 12.0% 2.3% 9.6% 7.0% 0.7% 1.3% 6.4% 3.4% 96.6% 66.6% 1.3% 6% 45% 82% 7% 26% 96%
5766 75.7% 44 19 26 13 44% 58% 20% 45% 6.2% 6.1% 1.2% 5% 3.9% 0.8% 2.8% 8.1% 4.2% 95.8% 62.9% 1.9% 7% 49% 82% 6% 27% 95%
<0.001 <0.001 <0.001 <0.001 <0.001 0.001 0.085 <0.001 <0.001 0.001 <0.001 <0.001 0.068 0.068 0.006 0.466 0.466 <0.001 0.056 0.015 0.001 0.99 0.13 0.60 0.89
The BMI groups show significant differences concerning the relevant injuries leading to polytrauma. Suicide rates affect approximately twice as often the underweight group, whereas catecholamine therapy is least required in this subgroup. a AIS severity 3.
decreasing BMI (p = 0.006). Overall injury severity (ISS) was similar, with an average intergroup difference of about 3 points. There was, however, variation in predominant injury pattern. Head injury was less frequent in the underweight and obese BMI groups, whilst abdominal injuries had the highest prevalence rates in the underweight group. Catecholamine treatment was used less frequently in BMI Group I (2.2%) as compared to all other groups (about 7%). We found the lowest rate of prehospital intubation in the underweight group (39.6%). There was no significant difference concerning blood transfusion rates between BMI groups. There was also no significant difference regarding chest drain placement rates (p = 0.13), sedation (p = 0.98), prehospital resuscitation (p = 0.056), and intensive care unit admission (Table 1). Outcome Multiple organ failure and sepsis were significantly associated with BMI, where obese patients had approximately twice as many complications compared to underweight patients (Table 2).
The duration of in-hospital treatment, length of ICU stay, and duration of mechanical ventilation consistently increased with BMI. All differences were statistically significant (Table 2). Regarding hospital outcome there was a slight increase in mortality with higher BMI, but these differences were not significant (p = 0.76 (Table 2)). Conversely, the mortality rate within the first 24 h seemed to decrease nonsignificantly with increasing BMI, from 3.0% in BMI Group I to 2.2% in BMI Group IV (p = 0.77). Also there was an almost significant difference concerning prehospital CPR performed on 0% of the underweight patients (p = 0.056) compared to the normal (2.3%), overweight (2.0%) and obese (1.3%) patient groups. Since injury severity and injury pattern varied within the BMI groups, adjustment of outcome had to be considered. The difference between observed and expected outcome based on the RISC score was lowest in the underweight group. In multivariate analysis both underweight (BMI Group I) as well as obesity (BMI Group IV) show significant prognostic relevance for polytrauma outcome (odds ratio = 2.1 (BMI Group I), odds ratio = 1.6 (BMI Group IV) (Table 3). A BMI
Table 2 Outcome according to BMI subgroup.
Number of patients Death within the first 24 h Hospital mortality RISC mortality prognosis Multiple organ failure (MOF) Sepsis Duration of intubation (days) ICU stay (days) Hospital stay (days) Ventilator-free days (30 days) Time to death (days)
Group I underweight
Group II normal
Group III overweight
Group IV obese
All patients
p-Value
269 8 (3.0%) 21 (7.8%) 9.7% 11 (13.8%) 14 (5.3%) 3.7 7.8 23.6 24.5 5.7
2617 77 (2.9%) 202 (7.7%) 14.8% 183 (23.5%) 237 (9.6%) 6.5 10.7 26.8 22.1 10.1
2120 61 (2.9%) 176 (8.3%) 15.8% 158 (24.6%) 191 (9.5%) 6.8 11.2 28.0 21.9 16.6
760 17 (2.2%) 67 (8.8%) 13.2% 59 (30.3%) 81 (11.2%) 8.2 12.7 30.5 21.2 16.6
5766 163 (2.8%) 466 (8.1%) 14.7% 411 (24.2%) 523 (9.6%) 6.7 11.0 27.6 22.0 13.9
0.77 0.76 <0.001 0.031 0.053 <0.001 <0.001 <0.001 <0.001 <0.001
Multiple organ failure and sepsis were significantly associated with BMI, where obese patients had approximately twice as many complications compared to underweight patients. The duration of in-hospital treatment, length of ICU stay, and duration of mechanical ventilation consistently increased with BMI.
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Table 3 Result of multivariate analysis with BMI group and RISC score as predictors of hospital outcome (Group II used as reference group). Group BMI (reference BMI Group II) BMI Group I (underweight) BMI Group III (overweight) BMI Group IV (obese) RISC score Constant
Regression coefficient 0.733 0.003 0.472 0.919 1.250
p-Value
Odds ratio (OR)
95% confidence interval for OR
0.015 0.981 0.009 <0.001 <0.001
2.08 0.99 1.60 2.51 –
1.15–3.77 0.76–1.29 1.13–2.28 2.34–2.68 –
Underweight (BMI Group I) as well as obesity (BMI Group IV) in polytraumatized patients are associated with significantly increased mortality by multivariate logistic regression analysis with hospital mortality as the target variable. Overweight (BMI Group III) is not an indicator of higher mortality and has the same outcome as normal weight patients (BMI Group II).
between 25 and 30 (BMI Group III) was not associated with prognostic relevance. Regarding long-term outcome the Kaplan– Meier survival plot with cumulated survival curves showed a correlation between increased BMI and increased late mortality rates (Fig. 2). Discussion The present study was designed to investigate the effect of BMI on mortality risk and outcome in trauma patients, identifying specific time points of potential pitfalls in trauma care. An understanding of both obesity and underweight related complications is vital to those involved in trauma care. The prevalence of obesity is a rapidly growing problem in industrialized countries. The increasing rate of obese patients threatens to alter current medical and surgical practice.27 Obese patients are more likely to have substantial medical comorbidities and are at increased risk of postsurgical and posttraumatic complications.17,20 The study data confirms significant differences concerning the prevalence of hypertension, coronary heart disease, arrhythmia and chronic obstructive lung diseases in overweight and obese patients. Although there was no significant difference concerning the prevalence of diabetes. Our study demonstrates that obesity is significantly associated with increased mortality in polytraumatized patients. Although the population of trauma victims does not necessarily mirror the national population as a whole, the general trend towards increased obesity across age groups and gender can be expected
Fig. 2. Concerning long-term outcome the Kaplan–Meier survival plot with cumulated survival curves shows that elevated BMI is associated with late mortality.
to shift the population of injured patients as well.17 Thus the identification of critical time care windows is mandatory for modern trauma care. Our study shows that obesity is associated with multiorgan failure (MOF) and sepsis mortality in the longterm time whereas underweight is associated with an increased mortality rate in the first 24 h. In this retrospective analysis we found that obese and underweight patients have some minor differences regarding the mechanism of injury and injury patterns but show significant higher mortality rates than normal weight patients, especially when adjusted for admission status. In our study 0% of the underweight patients underwent prehospital CPR. Accounting the fact, that patients dead on hospital arrival or accident scene are not included into the Trauma Registry Database, might contribute to the feeling that these patients have an even higher 24 h mortality after trauma than can be proved with our data. Brown et al. found that obese patients had a higher incidence of chest injury and lower extremity fractures. Nevertheless they face a lower incidence of head injury.21 Arabi et al.22 also reported a higher frequency of lower extremity fractures, but a lower frequency of abdominal injuries, invoking the ‘‘cushion effect’’ of the obese abdomen protecting the abdominal viscera from injury. In our study we found a similar overall Injury Severity Score (ISS) between all BMI groups, with an average difference of about 3 points. There is, however, variation in the injury pattern. Head injury was less frequent in the underweight and obese BMI groups, whilst abdominal injury rates were highest in the underweight subgroup. Our study indicates an increased risk of MOF and sepsis in obese patients after trauma compared to normal and underweight patients. A hypothetical explanation for this is that the inflammatory response triggered in severe trauma could have an altered, more fatal manifestation in obese patients. Similar results were found in other studies.1 Smith-Choban et al.15 found that 7 of 8 severely overweight trauma patients died from acute respiratory distress syndrome, an inflammation-mediated event. Other studies documented that the presence of MOF in morbidly obese patients in a medical intensive care unit is the strongest independent predictor of mortality.23 The duration of ICU stay might also contribute to higher mortality. In our study we found that the duration of in-hospital treatment, the length of ICU stay, and duration of mechanical ventilation consistently increased with an increasing BMI. All differences were significant and associated with a significant higher mortality rate in the obese BMI Group IV. Other studies have identified the need for transfusion of packed red blood cells (pRBC) during resuscitation as an independent risk factor for posttraumatic complications and organ dysfunction. In the present study we found no statistical significant relationship between pRBC transfusion rates during resuscitation after adjusting for these factors between underweight, normal weight, overweight, and obesity. This was surprising as we expected higher transfusion rates in the underweight collective due to low functional reserves and a suspected higher impact of equivalent blood loss in trauma. Furthermore this is found to be important for evaluating the effect of obesity and underweight on posttraumatic
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complications independent of the effects of blood transfusion. The nature of substantial body mass both in obese and underweight patients has an impact on how health care providers deliver medical care. In our study, we showed that obese patients have a considerably increased duration of ventilator use with concomitant increased pneumonia rates. This might be, in part, because of an intrinsic reduced lung capacity and increased work of breathing. These patients are also at greater risk of aspiration pneumonia.24 Difficulties in maintaining peripheral i.v. lines increase the use of central venous catheters. In critically ill obese patients, the persistent need for venous access is common and promotes the practice of long-term central access. This practice can increase the risk of catheter-associated sepsis, increasing the risk of MOF and sepsis in obese trauma patients. These factors may play a role in delaying early and consequent trauma care. Due to the shift of physical landmarks, underweight as well as obesity can adversely affect efficient trauma health care delivery, preventing health care providers from performing pivotal procedures. Procedures such as endotracheal intubation or tracheostomy are more challenging because of immobility or thickness of subcutaneous tissue of the neck.25 Vascular access in obese patients can also be complicated. Placement of central lines can be difficult because of lack of anatomical landmarks and increased distance to vessels.26 There was a significant intergroup difference concerning intubation rates and use of catecholamines, but we could not detect a significant difference concerning chest drain placement rates. Our study has some limitations. A substantial number of patients had no data regarding height and/or weight and had to be excluded. However, these patients’ characteristics were similar to those of the whole group. Furthermore, the categorization which we chose might have compromised the results. Patients with a BMI of 19 are usually considered as ‘normal’ but we place them in the ‘underweight’ group, mainly because of the limited sample size in this subgroup. Although we have found an association between obesity and trauma mortality, we can only hypothesize concerning the reasons for this association. Due to the retrospective nature of the study, we were not able to account for other medical conditions that may have confounded our results and lead to an increased mortality in this group. Although we found a trend towards higher complication rates in obese patients, we were unable to identify precipitating factors for MOF and sepsis. Conclusion We found that both obesity and underweight are independent risk factors for increased polytrauma mortality and therefore have to be taken into account in polytrauma management. The duration of in-hospital treatment, length of ICU stay, and duration of mechanical ventilation consistently increased with BMI. We also found an increased MOF and sepsis rate in obese patients. This is crucial for adequately allocating intensive care resources in advance. These findings, in conjunction with evidence for an altered inflammatory potential in obese patients, might furthermore lead to potential therapeutic targets to improve outcomes in both obese and underweight patients. The general shift towards a more obese population emphasizes the need for long-term adjustment of medical and financial concepts. The BMI group associated variation of injury pattern should lead to an additional focused assessment of those body parts anticipating injuries to
benefit from early identification. Anticipating BMI group specific critical trauma time care windows is mandatory for effective modern polytrauma management.
Conflict of interest statement There are no conflicts of interest.
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