[Associations of body mass index and waist circumference with risk of chronic kidney disease in adults in China].

Objective: To examine the associations of BMI and waist circumference (WC) with the risk of chronic kidney disease (CKD) and its subtypes in adults in China. Methods: The data from the China Kadoorie Biobank were used. After excluding those with cancer, coronary heart disease, stroke, or CKD at baseline survey, 480 430 participants were included in this study. Their body height and weight, and WC were measured at baseline survey. Total CKD was defined as diabetic kidney disease (DKD), hypertensive nephropathy (HTN), glomerulonephritis (GN), chronic tubulointerstitial nephritis (CTIN), obstructive nephropathy (ON), CKD due to other causes, and chronic kidney failure. Cox proportional hazards regression model was used to estimate the associations between exposure factors and risks of outcomes. Results: During a follow-up period of (11.8±2.2) years, 5 486 cases of total CKD were identified, including 1 147 cases of DKD, 340 cases of HTN, 1 458 cases of GN, 460 cases of CTIN, 598 cases of ON, 418 cases of CKD due to other causes, and 1 065 cases of chronic kidney failure. After adjusting for socio-demographic factors, lifestyle factors, baseline prevalence of hypertension and diabetes, and WC and compared to participants with normal BMI (18.5-23.9 kg/m2), the hazard ratios (HRs) of total CKD for underweight (<18.5 kg/m2), overweight (24.0-27.9 kg/m2), and obese (≥28.0 kg/m2) were 1.42 (95%CI: 1.23-1.63), 1.00 (95%CI: 0.93-1.08) and 0.98 (95%CI: 0.87-1.10), respectively. Stratification analysis by WC showed that BMI was negatively associated with risk for total CKD in non-central obese participants (WC: <85.0 cm in men and <80.0 cm in women) (HR=0.97, 95%CI: 0.96-0.99), while the association was positive in central obese participants (≥90.0 cm in men and ≥85.0 cm in women) (HR=1.03, 95%CI: 1.01-1.05). The association between BMI and GN was similar to that of total CKD. BMI was associated with an increased risk for HTN, with a HR of 1.12 (95%CI: 1.06-1.18) per 1.0 kg/m2 higher BMI. After adjusting for potential confounders and BMI, compared to participants with non-central obesity, the HRs for pre-central obesity (WC: 85.0-89.9 cm in men and 80.0-84.9 in women) and central obesity were 1.26 (95%CI: 1.16-1.36) and 1.32 (95%CI: 1.20-1.45), respectively. With the exception of HTN and CTIN, WC was positively associated with risks for all CKD subtypes. Conclusions: BMI-defined underweight and central obesity were independent risk factors for total CKD, and BMI and WC had different associations with risks for disease subtypes.