A Prospective Study of Frailty in Nephrology-Referred Patients With CKD

Abstract

Frailty is a construct developed to characterize a state of reduced functional capacity in older adults. However, there are limited data describing the prevalence or consequences of frailty in middle-aged patients with chronic kidney disease (CKD). Observational study. 336 non-dialysis-dependent patients with stages 1-4 CKD with estimated glomerular filtration rate (eGFR) <90 mL/min/1.73 m(2) (by the CKD-EPI [CKD Epidemiology Collaboration] serum creatinine-based equation) or evidence of microalbuminuria enrolled in the Seattle Kidney Study, a clinic-based cohort study. Findings were compared with community-dwelling older adults in the Cardiovascular Health Study. Prevalence and determinants of frailty in addition to its association with the combined outcome of all-cause mortality or renal replacement therapy. We defined frailty according to established criteria as 3 or more of the following characteristics: slow gait, weakness, unintentional weight loss, exhaustion, and low physical activity. We estimated kidney function using serum cystatin C concentrations (eGFR(cys)) to minimize confounding due to relationships of serum creatinine levels with muscle mass and frailty. The mean age of the study population was 59 years and mean eGFR(cys) was 51 mL/min/1.73 m(2). The prevalence of frailty (14.0%) was twice that of the much older non-CKD reference population (P < 0.01). The most common frailty components were physical inactivity and exhaustion. After adjustment including diabetes, eGFR(cys) categories of <30 and 30-44 mL/min/1.73 m(2) were associated with a 2.8- (95% CI, 1.3-6.3) and 2.1 (95% CI, 1.0-4.7)-fold greater prevalence of frailty compared with GFR(cys) ≥60 mL/min/1.73 m(2). There were 63 events during a median 987 days of follow-up. After adjustment, the frailty phenotype was associated with an estimated 2.5 (95% CI, 1.4-4.4)-fold greater risk of death or dialysis therapy. Cross-sectional study design obscures inference regarding temporal relationships between CKD and frailty. Frailty is relatively common in middle-aged patients with CKD and is associated with lower eGFR(cys) and increased risk of death or dialysis therapy.