Body Mass Index Modifies The Protective Association of Physical Activity With Incident Chronic Kidney Disease: A...

The interaction between physical activity (PA) and body mass index (BMI) on chronic kidney disease (CKD) risk is not well defined. This study aimed to investigate the independent and joint effects of PA and BMI on CKD incidence within the context of public health. This prospective cohort analysis included 11,597 adults with normal renal function from the Shanghai Suburban Adult Cohort and Biobank (SSACB). PA (MET-min/week) and BMI (kg/m²) were assessed at baseline and not updated during follow-up. Incident CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² and/or a urine albumin-to-creatinine ratio (ACR) ≥30 mg/g at follow-up, consistent with KDIGO criteria. Cox regression models were used to assess main effects and the PA×BMI interaction. Over a median follow-up of 3.0 years, 485 incident CKD cases occurred. Higher PA was associated with lower CKD risk (per 1000 MET-min/week: HR = 0.91, 95% CI: 0.84-0.98). A significant interaction was observed (P = 0.031), indicating that the protective effect of PA was more pronounced at higher BMI levels. Specifically, each 1000 MET-min/week increase in PA was associated with a greater reduction in CKD risk in individuals with obesity (HR = 0.72) compared with those with overweight (HR ≈ 0.84). The protective effect of PA on CKD risk is modified by BMI, with greater benefits observed in individuals with overweight or obesity. These findings support prioritizing combined PA and weight management strategies for high-risk populations.