Does body mass index category affect 60-day in-hospital death and ICU-acquired infection in adult ICU patients?
In critically ill adult patients, being overweight or morbidly obese is associated with lower in-hospital mortality compared to normal weight, demonstrating an obesity paradox in the ICU.
OBJECTIVE: To assess the effect of body mass index on ICU outcome and on the development of ICU-acquired infection. DESIGN: A substudy of the Intensive Care Over Nations audit. SETTING: Seven hundred thirty ICUs in 84 countries. PATIENTS: All adult ICU patients admitted between May 8 and 18, 2012, except those admitted for less than 24 hours for routine postoperative monitoring (n = 10,069). In this subanalysis, only patients with complete data on height and weight (measured or estimated) on ICU admission in order to calculate the body mass index were included (n = 8,829). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Underweight was defined as body mass index less than 18.5 kg/m, normal weight as body mass index 18.5-24.9 kg/m, overweight as body mass index 25-29.9 kg/m, obese as body mass index 30-39.9 kg/m, and morbidly obese as body mass index greater than or equal to 40 kg/m. The mean body mass index was 26.4 ± 6.5 kg/m. The ICU length of stay was similar among categories, but overweight and obese patients had longer hospital lengths of stay than patients with normal body mass index (10 interquartile range, 5-21 and 11 5-21 vs 9 4-19 d; p < 0.01 pairwise). ICU mortality was lower in morbidly obese than in normal body mass index patients (11.2% vs 16.6%; p = 0.015). In-hospital mortality was lower in morbidly obese and overweight patients and higher in underweight patients than in those with normal body mass index. In a multilevel Cox proportional hazard analysis, underweight was independently associated with a higher hazard of 60-day in-hospital death (hazard ratio, 1.32; 95% CI, 1.05-1.65; p = 0.018), whereas overweight was associated with a lower hazard (hazard ratio, 0.79; 95% CI, 0.71-0.89; p < 0.001). No body mass index category was associated with an increased hazard of ICU-acquired infection. CONCLUSIONS: In this large cohort of critically ill patients, underweight was independently associated with a higher hazard of 60-day in-hospital death and overweight with a lower hazard. None of the body mass index categories as independently associated with an increased hazard of infection during the ICU stay.
Sakr et al. (Fri,) studied this question.