Overweight, obesity, and the development of stage 3 CKD: the Framingham Heart Study.

BACKGROUND

Prior research yielded conflicting results about the magnitude of the association between body mass index (BMI) and chronic kidney disease (CKD).

STUDY

DESIGN

Prospective cohort study.

SETTINGS &

PARTICIPANTS

Framingham Offspring participants (n = 2,676; 52% women; mean age, 43 years) free of stage 3 CKD at baseline who participated in examination cycles 2 (1978-1981) and 7 (1998-2001).

PREDICTOR: BMI.

OUTCOME: Stage 3 CKD (estimated glomerular filtration rate < 59 mL/min/1.73 m(2) for women and < 64 mL/min/1.73 m(2) for men).

MEASUREMENTS: Age-, sex-, and multivariable-adjusted (diabetes, systolic blood pressure, hypertension treatment, current smoking status, and high-density lipoprotein cholesterol level) logistic regression models were used to examine the relationship between BMI at baseline and incident stage 3 CKD and incident dipstick proteinuria (trace or greater).

RESULTS

At baseline, 36% of the sample was overweight and 12% was obese; 7.9% (n = 212) developed stage 3 CKD during 18.5 years of follow-up. Relative to participants with normal BMI, there was no association between overweight individuals and stage 3 CKD incidence in age- and sex-adjusted models (odds ratio [OR], 1.29; 95% confidence interval [CI], 0.93 to 1.81; P = 0.1) or multivariable models (OR, 1.06; 95% CI, 0.75 to 1.50; P = 0.8). Obese individuals had a 68% increased odds of developing stage 3 CKD (OR, 1.68; 95% CI, 1.10 to 2.57; P = 0.02), which became nonsignificant in multivariable models (OR, 1.09; 95% CI, 0.69 to 1.73; P = 0.7). Similar findings were observed when BMI was modeled as a continuous variable or quartiles. Incident proteinuria occurred in 14.4%; overweight and obese individuals were at increased odds of proteinuria in multivariable models (OR, 1.43; 95% CI, 1.09 to 1.88; OR, 1.56; 95% CI, 1.08 to 2.26, respectively).

LIMITATIONS: BMI is measure of generalized obesity and not abdominal obesity. Participants are predominantly white, and these findings may not apply to different ethnic groups.

CONCLUSIONS

Obesity is associated with increased risk of developing stage 3 CKD, which was no longer significant after adjustment for known cardiovascular disease risk factors. The relationship between obesity and stage 3 CKD may be mediated through cardiovascular disease risk factors.