Obesity and risk of end-stage renal disease in patients with chronic kidney disease: a cohort study

Background: Obesity is a risk factor for de novo chronic kidney disease (CKD) in the general population. Obesity has been increasingly prevalent in patients with CKD and may lead to further progression of pre-existing CKD. However, whether obesity is associated with the development of end-stage renal disease (ESRD) in patients with CKD is not well understood. Objective: We investigated the impact of obesity on ESRD (needing chronic dialysis treatment or pre-emptive renal transplantation) or all-cause mortality in patients with moderate to advanced CKD. Design: A total of 322 patients with stages 3-5 CKD who were not yet on dialysis were prospectively followed for a median of 4.9 y. Obesity was defined by body mass index (BMI, in kg/m(2)) >= 30 or body fat percentage (BF%) >25% in men and >35% in women. BF% was assessed with the use of the Body Composition Monitor, a multifrequency bioimpedance spectroscopy device. Results: In total, 100 participants progressed to ESRD and 39 participants died. Obesity, whether defined by BMI or BF%, was not associated with a significantly increased risk of ESRD in Cox proportional hazards models that adjusted for age, sex, diabetes mellitus, cardiovascular disease, estimated glomerular filtration rate, urine protein: creatinine ratio, high-sensitivity C-reactive protein, and use of renin-angiotensin-aldosterone system inhibitors or statins, accounting for the competing risk for mortality (subdistribution HR: 1.15; 95% CI: 0.62, 2.14 for BMI-defined obesity and subdistribution HR: 0.84, 95% CI: 0.54, 1.29 for BF%-defined obesity, respectively). Results were similar when BMI and BF% were analyzed as continuous or time-dependent variables. Whereas higher BMI was protective, higher BF% appeared to be associated with increased all-cause mortality. Conclusions: Obesity did not confer an increased risk of ESRD in patients with moderate to advanced CKD.