Body mass index and causes of death in chronic kidney disease

In chronic kidney disease (CKD), a higher body mass index (BMI) is associated with a lower risk for death, but cause-specific death details are unknown across the BMI range. To define this, we studied 54,506 patients with CKD (stage 3 CKD- [91.5%]) from an institutional electronic medical record based-registry. We examined the associations among various causes of death (cardiovascular-, malignancy- and noncardiovascular/nonmalignancy-related deaths) across the BMI range using Cox proportional hazards and competing risks regression models. During a median follow-up of 3.7 years, 14,518 patients died. In the multivariable model, an inverted J-shaped association was noted between BMI and cardiovascular-related, malignancy-related, and noncardiovascular/nonmalignancy-related deaths. Similar associations were noted for BMI 25-29.9, 30-34.9, and 35-39.9 kg/m2 categories. A BMI >40 kg/m2 was not associated with cardiovascular-related and noncardiovascular/nonmalignancy-related deaths in CKD. Sensitivity analyses yielded similar results even after adjusting for proteinuria and excluding diabetes and hypertension from the models. In CKD, compared with a BMI of 18.5-24.9 kg/m2, those who are overweight, with class 1 and 2 obesity have a lower risk for cardiovascular-related, malignancy-related, and noncardiovascular/nonmalignancy-related deaths. Future studies should examine the associations of other measures of adiposity with outcomes in CKD.