Epidemiology of chronic kidney disease among older adults: a focus on the oldest old.

The National Kidney Foundation (NKF), Kidney Disease Outcomes Quality Initiative (KDOQI) Clinical Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification, and Stratification expanded the focus of chronic kidney disease (CKD) management from end-stage renal disease (ESRD) to the entire spectrum of kidney disease including early kidney damage through the stages of kidney disease to kidney failure. A consequence of these guidelines is that a large number of older adults are being identified as having CKD, many of whom will not progress to ESRD. Concerns have been raised that reduced estimated glomerular filtration rate (eGFR) among older adults may not represent "disease" and using age-specific cut-points for staging CKD has been proposed. This implies that among older adults, CKD, as currently defined, may be benign. Several recent studies have shown that among people greater than or equal to 80 years old, CKD is associated with an increased risk for concurrent complications of CKD (eg, anemia, acidosis) and adverse outcomes including mortality and cardiovascular disease (CVD). Further, among older adults, CKD is associated with problems not traditionally thought to be associated with kidney disease. These nondisease-specific outcomes include functional decline, cognitive impairment, and frailty. Future research studies are necessary to determine the impact of concurrent complications of CKD and nondisease-specific problems on mortality and functional decline, the longitudinal trajectories of CKD progression, and patient preferences among the oldest old with CKD.