Obesity and the Risk of Cardiovascular and All-Cause Mortality in Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Nephrol Dial Transplant. 2017 Mar 1;32(3):439-449. doi: 10.1093/ndt/gfw075.

Abstract

Background: Obesity is a risk factor for cardiovascular disease and death in people without chronic kidney disease (CKD), but the effect of obesity in people with CKD is uncertain.

Methods: Medline and Embase (from inception to January 2015) were searched for cohort studies measuring obesity by body mass index (BMI), waist:hip ratio (WHR) and/or waist circumference (WC) and all-cause and cardiovascular mortality or events in patients with any stage of CKD. Data were summarized using random effects models. Meta-regression was conducted to assess sources of heterogeneity.

Results: Of 4065 potentially eligible citations, 165 studies ( n = 1 534 845 participants) were analyzed. In studies that found a nonlinear relationship, underweight people with CKD (3-5) on hemodialysis experienced an increased risk of death compared with those with normal weight. In transplant recipients, excess risk was observed at levels of morbid obesity (>35 kg/m 2 ). Of studies that found the relationship to be linear, a 1 kg/m 2 increase in BMI was associated with a 3 and 4% reduction in all-cause and cardiovascular mortality in patients on hemodialysis, respectively {adjusted hazard ratio [HR] 0.97 [95% confidence interval (CI) 0.96-0.98] and adjusted HR 0.96 (95% CI 0.92-1.00)}. In CKD Stages 3-5, for every 1 kg/m 2 increase in BMI there was a 1% reduction in all-cause mortality [HR 0.99 (95% CI 0.0.97-1.00)]. There was no apparent association between obesity and mortality in transplanted patients or those on peritoneal dialysis. Sparse data for WHR and WC did not allow further analyses.

Conclusions: Being obese may be protective for all-cause mortality in the predialysis and hemodialysis populations, while being underweight suggests increased risk, but not in transplant recipients.

Keywords: cardiovascular mortality; chronic kidney disease; meta-analysis; mortality; obesity; systematic review.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Body Mass Index
  • Cardiovascular Diseases / mortality*
  • Cause of Death
  • Cohort Studies
  • Humans
  • Kidney Transplantation
  • Mortality*
  • Obesity / epidemiology
  • Obesity, Morbid / epidemiology*
  • Proportional Hazards Models
  • Renal Dialysis
  • Renal Insufficiency, Chronic / epidemiology*
  • Renal Insufficiency, Chronic / therapy
  • Risk Factors
  • Waist Circumference
  • Waist-Hip Ratio