Higher BMI is associated with reduced mortality but longer hospital stays following ICU discharge in critically ill Asian patients

Abstract

Background & aims: Asians with similar body mass index (BMI) as the Caucasians are at higher health risk as compared to their counterparts. Although the mean weight of patients admitted to the intensive care unit (ICU) is increasing but the relation between BMI with 28-day mortality and length of stay (LOS) following ICU discharge in Asian patients is not well studied.

Methods: We included all adult patients admitted to the ICU of a tertiary hospital who received mechanical ventilation (MV) for at least 48 hours between October 2013 and September 2014. Demographics, BMI, MV, comorbidities, ICU scores (Acute Physiology And Chronic Health Evaluation (APACHE) II and sequential organ failure assessment (SOFA)), use of vasopressor, renal replacement therapy and calorie supplementation were collected from the ICU database. BMI was categorized into four groups according to the World Health Organization's Asian BMI recommendation. Post-ICU LOS (days) was calculated from ICU discharge to hospital discharge in hospital survivors. We used multivariable logistic regression to identify factors associated with 28-day mortality and post-ICU LOS of more than 7 days.

Results: In a cohort of 273 patients (male 62%, mean age 58.4 ± 17 years), the prevalence of overweight/obesity was 53%. In the bivariate analysis, 28-day mortality was lower (p = 0.014) and post-ICU LOS longer (p = 0.01) in the overweight/obese groups. In the multivariable logistic regression analysis, APACHE II (Odds ratio, OR 1.10, CI 1.05-1.16), SOFA (OR 1.17, CI 1.05-1.31), duration of MV (days, OR 1.14, CI 1.05-1.25) were associated with increased and higher BMI groups (p < 0.001) with decreased 28-day mortality. Further analysis of 196 hospital survivors showed age (OR 1.04, CI 1.02-1.06), duration of MV (days, OR 1.14, CI 1.02-1.27) and higher Asian BMI (p = 0.042) were associated with longer post-ICU LOS. The odds of longer post-ICU LOS amongst overweight and obese patients were 1.27 (CI 0.59-2.73) and 1.62 (CI 0.69-3.81) times that of those with normal BMI respectively.

Conclusion: In multiethnic critically ill Asian patients, the prevalence of overweight/obesity was high. Although higher BMI was associated with reduced risk of 28-day mortality, obese patients stayed significantly longer in the hospital following ICU discharge.

Keywords: Body mass index; Intensive care unit; Length of stay; Mortality.