Rates of Treated and Untreated Kidney Failure in Older vs Younger Adults

CONTEXT: Studies of kidney failure in older adults have focused on receipt of dialysis, which may underestimate the burden of disease if older people are less likely to receive treatment. OBJECTIVE: To determine the extent to which age is associated with the likelihood of treatment of kidney failure. DESIGN, SETTING, AND PARTICIPANTS: Community-based cohort study of 1,816,824 adults in Alberta, Canada, who had outpatient estimated glomerular filtration rate (eGFR) measured between May 1, 2002, and March 31, 2008, with a baseline eGFR of 15 mL/min/1.73 m2 or higher and who did not require renal replacement therapy at baseline. Age was categorized as 18 to 44, 45 to 54, 55 to 64, 65 to 74, 75 to 84, and 85 or more years and eGFR as 90 or higher, 60 to 89, 45 to 59, 30 to 44, and 15 to 29 mL/min/1.73 m2. MAIN OUTCOME MEASURES: Adjusted rates of treated kidney failure (receipt of dialysis or kidney transplantation), untreated kidney failure (progression to eGFR <15 mL/min/1.73 m2 without renal replacement therapy), and death. RESULTS: During a median follow-up of 4.4 years, 97,451 (5.36%) died, 3295 (0.18%) developed kidney failure that was treated and 3116 (0.17%) developed kidney failure that went untreated. Within each eGFR stratum the rate of treated kidney failure was higher in younger compared with older people. For example, in the lowest eGFR stratum (15-29 mL/min/1.73 m2), adjusted rates of treated kidney failure were more than 10-fold higher among the youngest (18-44 years) compared with the oldest (≥85 years) groups (adjusted rate, 24.00 95% CI, 14.78-38.97 vs 1.53 95% CI, 0.59-3.99 per 1000 person-years, respectively; P < .001). Rates of untreated kidney failure were consistently higher at older ages. In the eGFR stratum of 15 to 29 mL/min/1.73 m2, adjusted rates of untreated kidney failure were more than 5-fold higher among the oldest (≥85 years), compared with the youngest (18-44 years) groups (adjusted rate, 19.95 95% CI, 15.79-25.19 vs 3.53 95% CI, 1.56-8.01 per 1000 person-years, respectively; P < .001). Rates of kidney failure overall (treated and untreated combined) demonstrated less variation across age groups; eg, the adjusted rate per 1000 person years for those with eGFR of 15-29 mL/min/1.73 m2 was 36.45 (95% CI, 24.46-54.32) among participants aged 18 to 44 years and 20.19 (95% CI, 15.27-26.69) among those aged 85 years or older (P = .01). CONCLUSION: In Alberta, Canada, rates of untreated kidney failure are significantly higher in older compared with younger individuals.