Obesity as an effect modifier of the risk of death in chronic kidney disease

Abstract

In the general population, obesity is associated with increased risk of end-stage renal disease (ESRD), especially if obesity occurs during young adulthood. Obesity is also associated with increased cardiovascular risk and mortality in the general population. However, observational studies which focused on populations with ESRD have demonstrated a more indirect association between body mass index and mortality, and this association has been termed paradoxical. Some have questioned whether the association between obesity and mortality is modified by ESRD. In this review, we discuss effect modification and interaction and factors that may lead to an assumption of effect modification when we observe decreased mortality among obese adults with ESRD. We show that assumptions of the existence of effect modification may be incorrect when the analysis is conditioned on a particular disease state that is influenced by obesity.

Keywords: ESRD; effect modifier; mortality; obesity.