A. Grigorian1, N. T. Nguyen1, B. Smith1, B. J. Williams1, S. Schubl1, V. Joe1, D. Elfenbein1, J. Nahmias1 1University Of California – Irvine,Division Of Trauma, Burns & Surgical Critical Care,Orange, CA, USA
Introduction: Obesity is a well-known risk factor for diabetes and hypertension which are the leading causes of end-stage renal disease (ESRD). Obesity is also a risk factor for the development of acute kidney injury (AKI). The effect of obesity on the need for dialysis in trauma has not been elucidated. We hypothesized that patients with a higher body mass index (BMI) will have a higher risk for need of dialysis after trauma.
Methods: This was a retrospective analysis using the National Trauma Data Bank. We included all patients 18 years of age and older. Patients were grouped based on their BMI: normal (18.5-24.99 kg/m2), obese (30-34.99 kg/m2), severely obese (35-39.99 kg/m2) and morbidly obese (> 40 kg/m2). The primary outcome was the need for dialysis. Patients with chronic renal failure were excluded from the analysis since a high proportion of these patients may have been on dialysis prior to their admission. We performed a multivariate linear regression analysis after controlling for significant cofactors.
Results: There were 1,221,990 patients included in the study. The obese group differed from the normal BMI group by age (median, 52.0 vs 38.0), history of diabetes (17.7% vs 6.8%), amount of traumatic brain injury (27.6% vs 30.5%) and lower extremity injury (26.2% vs 23.8%) but no difference in injury severity score (p>0.05). The severely obese group were older (median, 53.0 vs 38.0), had more ESRD (1.5% vs 1.1%) and hypertension (41.6% vs 24.6%). Morbidly obese patients were older (median, 50.0 vs 38.0) and had more lower extremity injuries (30.6% vs 23.8%). There was no difference among groups in regards to ICU stay and ventilatory days (p>0.05). Morbidly obese patients had a higher incidence of rhabdomyolysis (0.1% vs 0.02%), AKI (1.1% vs 0.4%) and mortality (3.1% vs 2.8%). After adjusting for covariates, we found that BMI > 30 kg/m2 (Odds ratio [OR]=1.21, confidence intervals [CI] 1.10-1.33, p<0.001), BMI > 35 kg/m2 (OR=1.50, CI=1.34-1.80, p<0.001) and > 40 kg/m2 (OR=1.84, CI=1.64-2.06, p<0.001) had a stepwise increased need for dialysis after trauma.
Conclusion: Trauma patients with a BMI > 30 kg/m2 are associated with increased risk for dialysis in a large database. This holds true even after controlling for multiple well-known risk factors for acute renal failure in trauma patients. Aggressive screening and treatment of obese trauma patients may help prevent acute renal failure requiring dialysis.
