Chronic kidney disease among overweight and obesity with and without metabolic syndrome in an urban Chinese cohort

Background: It is widely accepted that metabolic syndrome is associated with an increased risk of chronic kidney disease (CKD). To investigate whether coexisting metabolic syndrome is a necessary condition for CKD in overweight and obese. Methods: A cohort study of 6852 Chinese individuals from August 2007 to December 2012. Examinations included a questionnaire, physical measurements, and blood sampling. Hazard ratios for incident CKD were estimated according to combinations of BMI category and absence or presence of metabolic syndrome. Results: For CKD, multivariable adjusted hazard ratios vs. normal weight individuals without metabolic syndrome were 1.31 (95 % CI, 0.89-1.92) in overweight and 2.39 (95 % CI, 1.27-4.52) in obese without metabolic syndrome and 1.54 (95 % CI, 1.18-3.95) in normal weight, 2.06 (95 % CI, 1.27-3.36) in overweight, and 2.77 (95 % CI, 1.42-4.31) in obese with metabolic syndrome. There were no interactions between BMI and absence or presence of metabolic syndrome on risk of CKD when BMI was categorized (normal weight, overweight, obese) (P = 0.17). Among individuals both with and without metabolic syndrome there were increasing cumulative incidences of CKD from normal weight through overweight to obese individuals (log-rank trend P = 0.04 to P < 0.001). Although the multivariable adjusted hazard ratio for CKD in individuals with vs. without metabolic syndrome was 1.82 (95 % CI, 1.20-2.78) within overweight and obese individuals (log-rank P = 0.005), only 26.1 % of the increased risk observed for BMI is explained by metabolic syndrome. Conclusions: These findings suggest overweight and obesity are risk factors for CKD regardless of the presence or absence of metabolic syndrome.