Obesity, Acute Kidney Injury, and Mortality in Critical Illness

Abstract

Background

Although obesity is associated with risk for chronic kidney disease (CKD) and improved survival, less is known about the associations of obesity with risk of acute kidney injury (AKI) and post-AKI mortality.

Methods

In a single-center inception cohort of almost 15,000 critically ill patients, we evaluated the association of obesity with AKI and AKI severity, as well as in-hospital and one-year survival. AKI was defined using the Kidney Disease Outcome Quality Initiative criteria.

Results

The AKI incidence rates for normal, overweight, Class I, II, and III Obesity were 18.6, 20.6, 22.5, 24.3 and 24.0 percent respectively, and the adjusted odds ratios of AKI were 1.18 [95% CI 1.06–1.31], 1.35 [1.19–1.53], 1.47 [1.25–1.73], 1.59 [1.31–1.87], compared to normal weight, respectively. Each 5 kg/m ² increase in body mass index (BMI) was associated with a 10% risk [95% CI 1.06–1.24; p<0.001] of more severe AKI. Within-hospital and one-year survival rates associated with the AKI episodes were similar across BMI categories. In conclusion, obesity is a risk factor for AKI injury, which is associated with increased short- and long-term mortality.