Physical Activity is Decreased in Veterans with Non-Dialysis Chronic Kidney Disease

Abstract

Chronic kidney disease (CKD) is the progressive deterioration of the kidney’s capacity to eliminate fluid and nitrogenous waste from the body. CKD is associated with diminished physical function and performance, slower walking speed, and greater risk of frailty. We hypothesized that older Veterans with non-dialysis CKD have lower levels of physical activity compared to age matched non-CKD hypertensive controls (HTN) and that low physical activity would be associated with worse renal function and physical function. PURPOSE: 1) Compare the physical activity (PA) levels of Veterans with non-dialysis CKD versus HTN controls; 2) Evaluate the association between renal functional and PA; 3) Evaluate the association of PA vs functional capacity. METHODS: 54 CKD and 32 HTN Veterans of comparable age (69 ± 6 vs 68 ± 7, p = 0.63) and BMI (30.9 ± 6.2 vs 29.9 ± 4.8 p = 0.43) had estimated glomerular filtration rate (eGFR) measured using the Modification of Diet in Renal Disease (MDRD) equation. eGFR between the CKD and HTN was 43.9 ± 14.4 vs 81.7 ± 19.6 (p < 0.001), respectively. Five days of physical activity were measured using a step activity monitor. Peak VO2 (ml/kg/min) was measured during a progressive graded exercise treadmill test to exhaustion. Group differences were analyzed by Student’s t-tests, and relationships were analyzed using Linear Regression. Data are mean ± standard deviation. RESULTS: The average steps walked per day were 34% lower among CKD patients compared to hypertensive controls (3359 ± 1832 vs 4410 ± 1645, p < 0.001). Lower eGFR was significantly associated with both fewer average steps per day (r = 0.36, p < 0.001) and a greater percentage of the day inactive (r = 0.35, p < 0.001). Veterans with less average steps per day have a lower functional capacity (r = 0.55, p < 0.001). CONCLUSIONS: Veterans with CKD have significantly lower physical activity and functional capacity compared to non-CKD hypertensive controls. Lower renal function is significantly associated with reduced physical activity and lower functional capacity. Low levels of habitual physical activity negatively affect physical fitness and function, and overtime may contribute to increased risk of morbidity and mortality and decreases in quality of life. Supported by the Department of Veterans Affairs Merit Award.