The association between midlife cardiorespiratory fitness and later life chronic kidney disease: The Cooper Center Longitudinal Study

Background Chronic kidney disease (CKD) is a major public health problem, particularly in older age and in those with diabetes mellitus (DM), with high comorbidity and treatment costs. Study design Prospective observational cohort study. Setting & participants 17,979 participants, 22% women with a mean age of 50.0 (SD 8.8), in the Cooper Center Longitudinal Study (CCLS) seen initially between 1971 to 2009 who also received Medicare coverage from 1999 to 2009. Predictors Age, body mass index, blood pressure, cholesterol, glucose levels, current tobacco use, and cardiorespiratory fitness. Outcomes Incident CKD and DM were determined from Medicare administrative claims data. Results During 116,973 person-years of observation, 2022 cases of incident CKD occurred. Multivariable-adjusted proportional hazards models revealed a 24% lower risk of CKD among moderate fit (hazards ratio[HR] 0.76, 95% CI 0.67–0.85 compared to low fit) and a 34% lower risk of CKD among high fit (HR 0.66, 95% CI 0.58–0.76 compared to low fit). Even following the development of DM, fitness was associated with lower risk of CKD (HR 0.94, 95% CI 0.89–0.99) per 1-MET increment. Limitations Relatively homogeneous population of well-educated Caucasians. Conclusion Results of the present study suggest that higher fitness is associated with lower risk of CKD decades later even in at-risk populations such as diabetics. The findings support a role for enhancing fitness through regular physical activity in preventive strategies for CKD including those who may develop DM in later life.