Extreme obesity and outcomes in critically ill patients

Chest. 2011 Nov;140(5):1198-1206. doi: 10.1378/chest.10-3023. Epub 2011 Aug 4.


Background: Recent literature suggests that obese critically ill patients do not have worse outcomes than patients who are normal weight. However, outcomes in extreme obesity (BMI ≥ 40 kg/m(2)) are unclear. We sought to determine the association between extreme obesity and ICU outcomes.

Methods: We analyzed data from a multicenter international observational study of ICU nutrition practices that occurred in 355 ICUs in 33 countries from 2007 to 2009. Included patients were mechanically ventilated adults ≥ 18 years old who remained in the ICU for > 72 h. Using generalized estimating equations and Cox proportional hazard modeling with clustering by ICU and adjusting for potential confounders, we compared extremely obese to normal-weight patients in terms of duration of mechanical ventilation (DMV), ICU length of stay (LOS), hospital LOS, and 60-day mortality.

Results: Of the 8,813 patients included in this analysis, 3,490 were normal weight (BMI 18.5-24.9 kg/m(2)), 348 had BMI 40 to 49.9 kg/m(2), 118 had BMI 50 to 59.9 kg/m(2), and 58 had BMI ≥ 60 kg/m(2). Unadjusted analyses suggested that extremely obese critically ill patients have improved mortality (OR for death, 0.77; 95% CI, 0.62-0.94), but this association was not significant after adjustment for confounders. However, an adjusted analysis of survivors found that extremely obese patients have a longer DMV and ICU LOS, with the most obese patients (BMI ≥ 60 kg/m(2)) also having longer hospital LOS.

Conclusions: During critical illness, extreme obesity is not associated with a worse survival advantage compared with normal weight. However, among survivors, BMI ≥ 40 kg/m(2) is associated with longer time on mechanical ventilation and in the ICU. These results may have prognostic implications for extremely obese critically ill patients.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Chi-Square Distribution
  • Critical Illness / mortality*
  • Female
  • Hospital Mortality
  • Humans
  • Length of Stay / statistics & numerical data
  • Male
  • Middle Aged
  • Obesity / complications*
  • Obesity / mortality*
  • Proportional Hazards Models
  • Respiration, Artificial
  • Risk Factors
  • Time Factors