1. ¹Center for Human Nutrition, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA
2. ²Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA

Correspondence: Y Wang, Center for Human Nutrition, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, Maryland 21205, USA. E-mail: ywang@jhsph.edu

Received 23 March 2007; Revised 30 May 2007; Accepted 19 June 2007; Published online 10 October 2007.

Abstract

This study aimed to comprehensively assess epidemiologic evidence on the relation between obesity and kidney disease (KD). From 247 retrieved articles via PubMed (1980–2006), 25 cohorts, 3 cross-sectional, and 19 case–control studies met inclusion criteria. Related data were extracted using a standardized protocol. We estimated the pooled relative risk (RR) and 95% confidence interval (95% CI) of KD for each body mass index (BMI) category compared with normal weight using meta-analysis models. Population attributable risk was also calculated. Compared with normal-weight individuals (18.5<BMI<25), overweight individuals (25BMI<30) had elevated risk for KD (RR=1.40; 95% CI 1.30–1.50); obese individuals were at much higher risk (RR=1.83 (1.57–2.13)). Obesity in women was associated with a higher risk than in men (RR=1.92 (1.78–2.07) vs 1.49 (1.36–1.63); P<0.001). Results from cohort studies in patient populations and cross-sectional and case–control studies all indicated a positive association between BMI and risks for KD outcomes. We estimated that 24.2% and 33.9% of KD cases among US men and women, respectively, and in industrialized countries, 13.8% in men and 24.9% in women, could be related to overweight and obesity. Obesity increases the risk for KD in the general population, and the association appears to be stronger in women than in men. Obesity adversely affects the progress of KD among patients with kidney-related diseases.