Association of Obesity and Kidney Function Decline among Non-Diabetic Adults with eGFR > 60 ml/min/1.73m²: Results from the Multi-Ethnic Study of Atherosclerosis (MESA)

Background: Obesity is associated with higher end-stage renal disease incidence, but associations with earlier forms of kidney disease remain incompletely characterized.

Methods: We studied the association of body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) with rapid kidney function decline and incident chronic kidney disease in 4573 non-diabetic adults with eGFR ≥ 60 ml/min/1.73m² at baseline from longitudinal Multi-Ethnic Study of Atherosclerosis cohort. Kidney function was estimated by creatinine and cystatin C. Multivariate analysis was adjusted for age, race, baseline eGFR, and hypertension.

Results: Mean age was 60 years old, BMI 28 kg/m², baseline eGFR_Cr 82 and eGFR_Cys 95 ml/min/1.73m². Over 5 years of follow up, 25% experienced rapid decline in renal function by eGFR_Cr and 22% by eGFR_Cys. Incident chronic kidney disease (CKD) developed in 3.3% by eGFR_Cys, 11% by eGFR_Cr, and 2.4% by both makers. Compared to persons with BMI < 25, overweight (BMI 25 - 30) persons had the lowest risk of rapid decline by eGFR_Cr (0.84, 0.71 - 0.99). In contrast, higher BMI categories were associated with stepwise higher odds of rapid decline by eGFR_Cys, but remained significant only when BMI ≥ 35 kg/m² (1.87, 1.41 - 2.48). Associations of BMI with incident CKD were insignificant after adjustment. Large WC and WHR were associated with increased risk of rapid decline only by eGFR_Cys, and of incident CKD only when defined by both filtration markers.

Conclusions: Obesity may be a risk factor for kidney function decline, but associations vary by filtration marker used.