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 eGFRCr 82 and eGFRCys 95
ml/min/1.73m2. Over 5 years of follow up, 25% experienced rapid
decline in renal function by eGFRCr and 22% by eGFRCys.
Incident chronic kidney disease (CKD) developed in 3.3% by eGFRCys,
11% by eGFRCr, 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
eGFRCr (0.84, 0.71 - 0.99). In contrast, higher BMI categories were
associated with stepwise higher odds of rapid decline by eGFRCys,
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 eGFRCys, 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.