Physical Activity and Clinical Outcomes in the Setting of Chronic Kidney Disease

Abstract

Background: Physical activity promotes diverse metabolic benefits that may counteract the toxic biochemical environment of chronic kidney disease (CKD). We tested the hypotheses that greater physical activity levels are associated with lower kidney disease progression, cardiovascular outcomes, and death in a prospective cohort study of stage III-IV CKD patients. Design and setting: We studied 304 participants from the Seattle Kidney Study, a Nephrology clinic-based study of CKD, who had an estimated glomerular filtration rate (eGFR) of 15 to 59 mL/min/1.73 m2. Participants completed questionnaires regarding the frequency and duration of physical activity, and we converted these responses to minutes/week. We used generalized estimating equations and proportional hazards models to quantify associations of physical activity with relative annual decline in eGFR, defined using longitudinal serum cystatin C, and time to clinical outcomes, respectively. Results: Mean eGFR at baseline was 38 mL/min/1.73 m2, mean age was 62 years and mean relative annual change in eGFR was -7%. After adjustment for potential confounders, greater physical activity levels were associated with statistically slower rates of kidney function decline. Each one-category increase in physical activity group was associated with a 1.9% per year slower decline in kidney function (p=0.031). During a median 3.3 years of follow-up, 54 participants died, 48 participants were hospitalized for heart failure and 28 participants developed a component of the composite cardiovascular outcome (incidence rates: 60, 52 and 13 per 1000 person-years, respectively). Our investigation found no association between either the presence or the duration of physical activity with all-cause mortality. On the other hand, we found associations of any physical activity with hospitalized heart failure and with a composite cardiovascular outcome after adjustment for established cardiovascular risk factors. Conclusions: Even moderate levels of physical activity may be sufficient to confer health benefits among CKD patients. Physical activity is emerging as one of few modifiable risk factors for major adverse health outcomes in this high-risk patient population.