Exercise capacity and risk of chronic kidney disease in US veterans: a cohort study

Abstract

Objective: To assess the association between exercise capacity and the risk of developing chronic kidney disease (CKD).

Patients and methods: Exercise capacity was assessed in 5812 male veterans (mean age, 58.4±11.5 years) from the Veterans Affairs Medical Center, Washington, DC. Study participants had an estimated glomerular filtration rate of 60 mL/min per 1.73 m(2) or more 6 months before exercise testing and no evidence of CKD. Those who developed CKD during follow-up were initially identified by the International Classification of Diseases, Ninth Revision and further verified by at least 2 consecutive estimated glomerular filtration rate values of less than 60 mL/min per 1.73 m(2) 3 months or more apart. Normal kidney function for CKD-free individuals was confirmed by sequential normal eGFR levels. We established 4 fitness categories on the basis of age-stratified quartiles of peak metabolic equivalents (METs) achieved: least-fit (≤25%; 4.8±0.90 METs; n=1258); low-fit (25.1%-50%; 6.5±0.96 METs; n=1614); moderate-fit (50.1%-75%; 7.7±0.91 METs; n=1958), and high-fit (>75%; 9.5±1.0 METs; n=1436). Multivariable Cox proportional hazard models were used to assess the association between exercise capacity and CKD.

Results: During a median follow-up period of 7.9 years, 1010 developed CKD (20.4/1000 person-years). Exercise capacity was inversely related to CKD incidence. The risk was 22% lower (hazard ratio, 0.78; 95% CI, 0.75-0.82; P<.001) for every 1-MET increase in exercise capacity. Compared with the least-fit individuals, hazard ratios were 0.87 (95% CI, 0.74-1.03) for low-fit, 0.55 (95% CI, 0.47-0.65) for moderate-fit, and 0.42 (95% CI, 0.33-0.52) for high-fit individuals.

Conclusion: Higher exercise capacity attenuated the risk of developing CKD. The association was independent and graded.