Background
Frail individuals are at increased risk for poor outcomes, including adverse drug events. Kidney function is often compromised in frailty and is a key consideration in medication choice and dosing; however, creatinine-based measures of kidney function may be biased in frail individuals.
Study Design
Observational study.
Setting & Participants
4,987 community-dwelling older men and women with complete data who participated in visit 5 of the Atherosclerosis Risk in Communities (ARIC) Study (2011–2013).
Predictor
Kidney measures included glomerular filtration rate (GFR) estimated using serum creatinine (eGFRcr) and serum cystatin C (eGFRcys) and urine albumin-creatinine ratio (ACR).
Outcomes
Frailty, defined using established criteria of 3 or more frailty characteristics (weight loss, slowness, exhaustion, weakness, and low physical activity).
Results
In total, 341 participants (7%) were classified as frail, 1475 (30%) had eGFRcr <60 ml/min/1.73 m2, 2480 (50%) had eGFRcys <60 ml/min/1.73 m2, and 1006 (20%) had albuminuria ≥30 mg/g. Among frail participants, prevalences of eGFRcr and eGFRcys <60 ml/min/1.73 m2 were 45% and 77%, respectively. Adjusted for covariates, frailty showed a moderate association with eGFRcr and a strong association with eGFRcys and ACR. Frail individuals with eGFRcr 60–<75 ml/min/1.73 m2 were frequently reclassified to lower eGFR categories using eGFRcys (49% to 45–<60, 32% to 30–<45, and 3% to <30 ml/min/1.73 m2). Hyperpolypharmacy (taking ≥10 classes of medications) was more common in frail individuals (54% vs 38% of non-frail), including classes requiring kidney clearance (e.g., digoxin) and associated with falls and subsequent complications (e.g., hypnotic/sedatives, anticoagulants).
Limitations
Cross-sectional study design.
Conclusions
Frail individuals had a high prevalence of reduce kidney function, with large discrepancies when reduced kidney function was classified by eGFRcys versus eGFRcr. Given the substantial medication burden and uncertainty in CKD classification, confirmation of kidney function with alternative biomarkers may be warranted to ensure careful prescribing practices in this vulnerable population.