Effect of obesity and underweight status on the hospital-acquired functional decline in patients with cardiovascular surgery: an analysis of data from a prospective observational multicenter cohort study.

The aim of this study was to determine the association between underweight or obese status and hospital- acquired functional decline (HAFD) following cardiovascular surgery. We performed a retrospective, observational, multicenter cohort study of cardiovascular surgery patients between April, 2010, and June, 2017. Body mass index (BMI) was categorized into four classes: underweight group (< 18.5 kg/m A total of 3,850 adult patients were included in the analysis data set (median age 72 years, 35% female). A total of 811 (21.0%) patients demonstrated HAFD: 27.2% in the underweight group, 21.3% in the normal weight group, 18.8% in the overweight group, and 19.3% in the obese group. The relative risk for HAFD was 1.381 (95% CI 1.052-1.814) for the underweight group versus the normal weight group, although that is comparable to the obese group after adjustment by confounding factors. Analyses of subgroup interactions showed that the relative risk of HAFD in the obese group compared with the normal group was higher in patients with muscle wasting (p < 0.05). HAFD was significantly worse for underweight patients following cardiovascular surgery. In contrast, obese status was not associated with HAFD, exclusive of the obese patients with muscle wasting.