Determinants of mobility decline in nephrology-referred patients with CKD: a longitudinal cohort study

Background and ObjectiveChronic kidney disease (CKD) is associated with loss of muscle quality leading to mobility limitation and decreased independence. Identifying predictors of gait speed decline may help target rehabilitative therapies to those at highest risk of mobility impairment. Design, setting and participants, and measurementsThe current prospective cohort study recruited ambulatory patients with stage 1-4 CKD (eGFR 15-89 ml/min/1.73m2) from nephrology clinics. Predictors included demographic and clinical variables including GFR estimated using serum cystatin C. Outcomes were average change in gait speed (m/s) per year and inclusion in the top tertile of gait speed decline over 3 years. Linear mixed models and relative risk regression were used to estimate associations with annual gait speed changes and fastest tertile of decline. ResultsAmong 213 participants, 81% were male, 22% were black and 43% had diabetes. Mean age was 57{+/-}13 years, median follow-up 3.15 years, mean baseline eGFRcysc 47.9{+/-}21ml/min/1.73 m2, and median baseline gait speed 0.95m/s [IQR 0.81, 1.10]. Lower baseline eGFRcysc was associated with more rapid loss of gait speed (-0.029 m/s/year [95% CI -0.042, -0.015] per 30 ml/min/1.73 m2 lower eGFR; p<0.001). Diabetes was associated with -0.024m/s/year faster change (95% CI -0.042, -0.007; p=.007). Lower eGFRcysc was associated with a 49% greater risk of rapid gait speed decline (IRR 1.49; 95% CI 1.11, 2.00, p=.008) after adjustment. Prevalent cardiovascular disease and African American race were associated with a 45% greater (IRR 1.45; 95% CI 1.04, 2.01, p=.03) and 58% greater rate of rapid gait speed decline (IRR 1.58; 95% CI 1.09, 2.29, p=.02), respectively. ConclusionsAmong ambulatory, disability-free patients with CKD, lower eGFRcysc and diabetes status were associated with faster gait speed decline. Lower eGFRcysc, cardiovascular disease, and African American race were associated with rapid gait speed decline.