An Advantage of Obesity?

The Modification of Diet in Renal Disease (MDRD) Study examined the effect of body mass index (BMI) on patients’ mortality. The study included 1,759 subjects with Chronic Kidney Disease (CKD) and was conducted over a ten year period. In the general population a higher BMI, which is a primary indicator of obesity, leads to an increased risk for cardiovascular disease (CVD) and CVD-induced death as well as all-cause mortality.

Strikingly, scientists noticed an interesting trend in patients with hemodialysis therapy and incident dialysis therapy (two common methods used to treat CKD). An increase in these patients’ BMI actually appears to be protective, leading to better survival rates and decreased cardiovascular death. In this group of patients with CKD, those who lost weight showed a poorer chance of survival. In addition, high BMI was associated with a lower chance of hospitalization and lower all-cause mortality.

Studies exist that published the exact opposite results of the MDRD Study. They claim that obesity in CKD patients puts them at a higher risk for CVD and thus mortality, just like the general population. Differences in the results may be explained by the severity of CKD of the patients in each study. Patients with earlier, less advanced stages of CKD seem to better reflect the general population. Patients with stage 3-4 CKD who had a high BMI, however, did show an overall better chance of survival compared with patients with a low BMI.

The authors make no mention of the causation of such a finding. Nor do they necessarily imply that having Chronic Kidney Disorder and being on hemodialysis therapy should justify obesity. Still, the article does provide some insight into the condition and treatment of patients with CKD and may spark a realization of how the disorder can be treated in the future.

Body Mass Index and Mortality in CKD. American Journal of Kidney Diseases - Volume 50, Issue 3 (September 2007) - Copyright © 2007 W. B. Saunders Company