Body mass index and mortality in CKD

Area of Science:

• Nephrology
• Epidemiology
• Public Health

Background:

• Higher body mass index (BMI) is linked to poorer survival in the general population.
• Paradoxically, increased BMI appears to offer a survival advantage in patients with kidney failure undergoing hemodialysis.
• Limited data exist on BMI's association with mortality in earlier stages of chronic kidney disease (CKD).

Purpose of the Study:

• To investigate the relationship between body mass index (BMI) and mortality in patients with chronic kidney disease (CKD).
• To determine if BMI is an independent predictor of all-cause and cardiovascular disease (CVD) mortality in CKD patients.

Main Methods:

• A cohort study involving 1,759 subjects from the Modification of Diet in Renal Disease (MDRD) Study.
• Body mass index (BMI) was assessed as a predictor variable.
• Cox proportional hazards models were used to analyze the association between BMI quartiles and all-cause and CVD mortality over a mean follow-up of 10 years.

Main Results:

• Unadjusted analyses showed higher BMI quartiles (3 and 4) were associated with increased risk of all-cause and CVD mortality.
• After multivariable adjustment for demographic, CVD, and kidney disease risk factors, this association was attenuated.
• Adjusted hazard ratios for quartiles 3 and 4 for all-cause mortality were 0.81 and 0.83, respectively.
• Adjusted hazard ratios for quartiles 3 and 4 for CVD mortality were 0.92 and 0.85, respectively.

Conclusions:

• In this cohort of individuals with predominantly non-diabetic CKD, BMI did not emerge as an independent predictor of all-cause or CVD mortality.
• The study's reliance on a single BMI measurement and its specific cohort (relatively young, white, non-diabetic CKD) may limit generalizability to all CKD populations.