Body Mass Index and Mortality in Korean Intensive Care Units: A Prospective Multicenter Cohort Study

Background: The level of body mass index (BMI) that is associated with the lowest mortality in critically ill patients in Asian populations is uncertain. We aimed to examine the association of BMI with hospital mortality in critically ill patients in Korea. Methods: We conducted a prospective multicenter cohort study of 3,655 critically ill patients in 22 intensive care units (ICUs) in Korea. BMI was categorized into five groups: <18.5, 18.5 to 22.9, 23.0 to 24.9 (the reference category), 25.0 to 29.9, and >= 30.0 kg/m(2). Results: The median BMI was 22.6 (IQR 20.3 to 25.1). The percentages of patients with BMI <18.5, 18.5 to 22.9, 23.0 to 24.9, 25.0 to 29.9, and >= 30.0 were 12, 42.3, 19.9, 22.4, and 3.3%, respectively. The Cox-proportional hazard ratios with exact partial likelihood to handle tied failures for hospital mortality comparing the BMI categories <18.5, 18.5 to 22.9, 25.0 to 29.9, and >= 30.0 with the reference category were 1.13 (0.88 to 1.44), 1.03 (0.84 to 1.26), 0.96 (0.76 to 1.22), and 0.68 (0.43 to 1.08), respectively, with a highly significant test for trend (p = 0.02). Conclusions: A graded inverse association between BMI and hospital mortality with a strong significant trend was found in critically ill patients in Korea.