Age and the eGFR-dependent risk for adverse clinical outcomes

Although the relative risk of kidney failure increases with more severe chronic kidney disease (CKD) independent of age, with older age the absolute risk of kidney failure at a given time horizon becomes smaller. In this article, we first review some epidemiological measures of outcome occurrence (absolute rate or risk) and association (relative measures: difference or ratio of rates or risks). We emphasize that relative measures need to be presented along with absolute measures to be understood and absolute risk is more helpful than absolute rate when making treatment decisions. We then apply these principles to the discussion of the absolute and relative rates or risks of kidney failure and death across categories of estimated glomerular filtration rate and age. Lastly, we discuss the implications of existing studies on whether the definition of CKD should account for age.