Swapna Abhyankar, Kira Leishear, Fiona M Callaghan, Dina Demner-Fushman, Clement J McDonald Critical Care 2012, 16:R235 (18 December 2012)
Introduction: Two-thirds of U.S. adults are overweight or obese, which puts them at higher risk of developing chronic diseases and of death compared to normal weight individuals. However, recent studies have found that overweight and obesity by themselves may be protective in some contexts, such as hospitalization in an intensive care unit (ICU). Our objective was to determine the relationship between body mass index (BMI) and mortality 30 days and one year after ICU admission.
Methods: We performed a cohort analysis of 16,812 adult patients from MIMIC-II, a large database of ICU patients at a tertiary care hospital in Boston, Massachusetts. The data were originally collected during the course of clinical care, and we subsequently extracted our dataset independently of the study outcome.
Results: Compared to normal weight patients, obese patients had 26% and 43% lower mortality risk at 30 days and one year after ICU admission, respectively (OR 0.74 [95% CI, 0.64-0.86] and 0.57 [95% CI, 0.49-0.67]); overweight patients had nearly 20% and 30% lower mortality risk (OR 0.81 [95% CI, 0.70-0.93] and 0.68 [95% CI, 0.59-0.79]). Severely obese patients (BMI [greater than or equal to]40 kg/m2) did not have a significant survival advantage at 30 days (OR 0.94 [95% CI, 0.74-1.20]), but did have 30% lower mortality risk at one year (OR 0.70 [95% CI, 0.54-0.90]). There was no significant difference in admission acuity or ICU and hospital length of stay across BMI categories.
Conclusion: Our study supports the hypothesis that patients who are overweight or obese have improved survival both 30 days and one year after ICU admission.
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