UCSF

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.