Progression and Regression of Chronic Kidney Disease by Age Among Adults in a Population-Based Cohort in Alberta, Canada

Abstract

Importance: The burden of chronic kidney disease (CKD) is expected to increase worldwide as the global population ages, potentially increasing the demand for nephrology services. Understanding whether CKD inevitably progresses or may regress can inform clinical decision-making and health policy.

Objective: To study CKD progression and regression by age in adults with CKD.

Design, setting, and participants: This population-based cohort study used linked administrative and laboratory data to assess adults in the province of Alberta, Canada, with incident mild, moderate, or severe CKD, defined by estimated glomerular filtration rate (eGFR) of 45 to 59, 30 to 44, or 15 to 29 mL/min/1.73 m2 for longer than 3 months, from April 1, 2009, to March 31, 2015. Data were analyzed from July 20 to November 30, 2020.

Exposures: Age.

Main outcomes and measures: Time to the earliest of CKD regression or progression (defined as sustained increase or drop in eGFR category for >3 months, respectively, and a ≥25% increase or decrease in eGFR from baseline, respectively), kidney failure (the earlier of kidney replacement initiation or eGFR <15 mL/min/1.73 m2 for >3 months), death, or censoring (outmigration, 5 years of follow-up, or end of study on March 31, 2017).

Results: Study participants with CKD (55.2% women and 44.8% men) included 81 320 with mild CKD (mean [SD] age, 72.4 [11.3] years), 35 929 with moderate CKD (mean [SD] age, 77.1 [11.5] years), and 12 237 with severe CKD (mean [SD] age, 76.6 [13.8] years). The annual incidence of CKD increased with advancing age, from 180 per 100 000 population younger than 65 years to 7250 per 100 000 in those 85 years or older. After cohort entry, the 5-year probability of regression was similar to that of progression or kidney failure in mild (14.3% vs 14.6%), moderate (18.9% vs 16.5%), and severe (19.3% vs 20.4%) CKD. As mortality at 5 years increased with advancing age in moderate (from 9.6% for age <65 years to 48.4% for age ≥85 years) and severe (from 10.8% for age <65 years to 60.2% for age ≥85 years) CKD, the risk of progression or kidney failure decreased substantially (for moderate CKD, from 32.3% for <65 years to 9.4% for ≥85 years; for severe CKD, from 55.2% for <65 years to 4.7% for ≥85 years), whereas the probabilities of regression varied to a lesser extent (for moderate CKD, from 22.5% for <65 years to 15.4% for ≥85 years; for severe CKD, from 13.9% for <65 years to 18.7% for ≥85 years).

Conclusions and relevance: This cohort study found that with advancing age, CKD regression and death were more likely than CKD progression or kidney failure. These findings have important implications for patient care and for assessing the potential effect of population aging on the burden of CKD.

Figure 1.. Incidence of Chronic Kidney Disease (CKD) by Stage and Patient Age

We measured the incidence of CKD using new cases of CKD (by stage) among adults in Alberta who had estimated glomerular filtration rate measurements (numerator) and estimates of the Alberta population (by age and year) from Statistics Canada (denominator).

Figure 2.. Outcome Probabilities at 5 Years From Study Entry

Outcome probabilities were estimated using cumulative incidence functions at 5 years after study entry. Progression represents chronic kidney disease (CKD) progression or kidney failure. The 5-year probabilities of CKD progression and kidney failure were 14.5% and less than 0.01%, respectively, for individuals with mild CKD and 16.2% and 0.3%, respectively, for individuals with moderate CKD.

Figure 3.. Outcome Probabilities at 5 Years From Study Entry by Age

Outcome probabilities were estimated using cumulative incidence functions at 5 years after study entry, stratified by categories of baseline age. Progression represents chronic kidney disease (CKD) progression or kidney failure. The 5-year probabilities of kidney failure were less than 0.1% for individuals with mild CKD, regardless of age; among individuals with moderate CKD, probabilities were 1.3% for those aged 18 to 64 years, 0.3% for those aged 65 to 74 years, 0.1% for those aged 75 to 84 years, and 0.1% for those 85 years or older.

Figure 4.. Time Spent in a Chronic Kidney Disease (CKD) Stage

Time spent in a CKD stage (disease duration) was estimated using the Kaplan-Meier method, comparing inclusion of CKD regression (Yes) vs exclusion of CKD regression (No) among the reasons to leave a CKD stage. The vertical dotted lines indicate time spent in a corresponding CKD stage in 75% of the individuals with mild CKD (A), in 50% of the individuals with moderate CKD (B), and in 50% of the individuals with severe CKD (C).