POS-334 CKD PROGRESSION AND REGRESSION BY AGE: A POPULATION-BASED COHORT STUDY

Abstract

The burden of chronic kidney disease (CKD) is expected to increase worldwide with global population aging, potentially increasing the demand for nephrology services. Understanding whether CKD inevitably progresses or may regress can inform clinical decision-making and health policy. We aimed to study both adverse and favorable kidney outcomes by age in adults with CKD. We conducted a population-based cohort study using linked administrative and laboratory data from Alberta, Canada. We included adults with incident mild, moderate or severe CKD, defined by outpatient estimated glomerular filtration rate (eGFR) of 45-59, 30-44, or 15-29 mL/min/1.73 m2 for >3 months, between April 1, 2009 and March 31, 2015. We excluded individuals who initiated kidney replacement or met the criteria for a more severe stage than the stage they qualified for at cohort entry. The exposure was baseline age. The outcome of interest was time to the earliest of CKD regression or progression (increase or drop in eGFR category for >3 months, accompanied by a ≥25% increase or decrease in eGFR from baseline), kidney failure (the earlier of kidney replacement initiation or eGFR <15 mL/min/1.73 m2 for >3 months), death, or censoring (out-migration, 5 years after study entry, or March 31, 2017). We used the non-parametric Aalen-Johansen method to estimate the cumulative incidence functions of these competing events. We included 81,320 individuals with mild, 35,929 with moderate, and 12,237 with severe CKD (mean age 72.4, 77.1, and 76.6 years, respectively). The yearly incidence of CKD increased with advancing age from 180 per 100,000 population at age <65 to 7,250 at age ≥85 years. Overall, regression of CKD was as common as progression in mild (5-year probabilities 14.3% vs. 14.5%) and moderate CKD (18.9% vs. 16.2%), and as common as kidney failure in severe CKD (19.3% vs. 20.4%). In people with moderate or severe CKD, the risk of progression or kidney failure decreased with advancing age, whereas the probability of regression did not vary substantially: from 21.5 to 18.3 and 15.4% in moderate CKD, and 19.8 to 22.4 and 18.7% in severe CKD for age groups 65-74, 75-84 and ≥85 years, respectively. Regression was more common in those with low-grade albuminuria; in people with normal to moderate albuminuria, regression tended to be less likely with advancing age, and more likely in more severe stages. We observed similar probabilities of regression in analyses that excluded participants at risk for acute kidney injury associated with emergency department visits, hospitalizations, and receipt of potentially nephrotoxic procedures or medications, or focused exclusively on those with CKD which had been stable for at least 1 year. With advancing age the incidence of CKD increases but CKD regression and death are more likely than CKD progression or kidney failure. Population aging may not necessarily translate into increased CKD burden for patients and health services.