CKD Prevalence and Incidence in Older Adults Using Estimated GFR With Different Filtration Markers: The Atherosclerosis Risk in Communities Study

Rationale & Objective: The prevalence of chronic kidney disease (CKD) is known to increase with age; however, creatinine may be a less reliable filtration marker in older adults. Few studies have investigated the prevalence and progression of CKD using different filtration markers for estimating glomerular filtration rate (GFR). Study Design: A prospective observational cohort study. Setting & Participants: 6,393 White and African American participants aged 65-100 years from the Atherosclerosis Risk in Communities Study (ARIC) at Visit 5, followed longitudinally at Visits 6 and 7. Exposure and Outcome: The eGFR was estimated either by creatinine (eGFRcr), cystatin C (eGFRcys), creatinine and cystatin C (eGFRcr-cys), or using creatinine, cystatin C, and beta- 2-microglobulin (eGFRcr-cys-b2m). CKD progression was defined as 30% decline in eGFR at follow-up visits. Analytical Approach: Logistic regression models, adjusted for sex, race and study center, diabetes, blood pressure, body mass index, prevalent cardiovascular disease, and heart failure. Results: At Visit 5, the mean age in the study population was 75.8 years, and the mean eGFR ranged from 71.2 to 61.2 mL/min/1.73m2 2 using eGFRcr or eGFRcys, respectively. The proportion with eGFR < 60 mL/min/1.73m2 2 was lowest with eGFRcr and highest with eGFRcys for all age groups, and prevalence increased with age for all markers. For example, the prevalence of eGFRcr < 60 mL/min/1.73m2 2 in ages 70-74 years ranged from 15% to 21% and in ages 85-89 years ranged from 38% to 46% at the different visits. The proportion with a 30% eGFR decline over a mean of 8 years in people who were originally aged 65-69 years ranged from 9% (eGFRcr)-18% (eGFRcys). More people with eGFRcr >= >= 60 mL/min/1.73m2 2 were reclassified to < 60 mL/min/1.73m2 2 when using eGFRcys (33%) compared with eGFRcr-cys (12%) or eGFRcr-cys-b2m (18%). The proportion with 30% eGFR decline was lowest with eGFRcr and highest with eGFRcys, with greater incidence in older age groups for all markers. Limitations: No direct measurement of GFR. Not all participants survived or attended subsequent follow-up visits. Conclusions: The prevalence and progression of CKD increase with age, but estimates vary with the filtration marker used. The eGFRcr gave the lowest estimate of CKD at 15% for people aged 65-69 years at Visit 5 while eGFRcys gave the highest estimates of CKD at 26% for that same population.