Rapid Kidney Function Decline and Mortality Risk in Older Adults

Background: Impaired kidney function is associated with increased mortality risk in older adults. It remains unknown, however, whether longitudinal declines in kidney function are independently associated with increased cardiovascular and all-cause mortality in older adults. Methods: The Cardiovascular Health Study evaluated a cohort of community-dwelling older adults enrolled from 1989 to 1993 in 4 US communities with follow-up through 2005. Among 4380 participants, the slope of annual decline in estimated glomerular filtration rate (eGFR) was estimated using both serum creatinine (eGFR(creat)) and cystatin C (eGFR(cys)) rates, which were measured at baseline, year 3, and year 7 of follow-up. Rapid decline in eGFR was defined as a loss greater than 3 mL/min/1.73 m(2) per year, and cardiovascular and all-cause mortality were assessed over a mean of 9.9 years of follow-up. Results: Mean (SD) levels of creatinine and cystatin C were 0.93 (0.30) mg/dL and 1.03 (0.25) mg/L, respectively; mean (SD) eGFR(creat) and eGFR(cys) were 79 (23) mL/min/1.73 m(2) and 79 (19) mL/min/1.73m(2), respectively. Individuals with rapid decline measured by eGFR(creat) (n = 714; 16%) had increased risk of cardiovascular (adjusted hazard ratio [AHR], 1.70; 95% confidence interval [CI], 1.40-2.06) and all-cause (AHR, 1.73; 95% CI, 1.54-1.94) mortality. Individuals with rapid decline measured by eGFR(cys) (n = 1083; 25%) also had increased risk of cardiovascular (AHR, 1.53; 95% CI, 1.29-1.80) and all-cause (AHR, 1.53; 95% CI, 1.38-1.69) mortality. The association of rapid decline in eGFR with elevated mortality risk did not differ across subgroups based on baseline kidney function, age, sex, race, or prevalent coronary heart disease. Conclusion: Rapid decline in eGFR is associated with an increased risk of cardiovascular and all-cause mortality in older adults, independent of baseline eGFR and other demographic variables.