Background: Patients with chronic kidney disease (CKD) treated with dialysis have reduced levels of physical functioning. Little is known of the physical functioning in patients prior to initiation of renal replacement therapy (RRT). The purpose of the study was 2-fold: (i) to document physical functioning of patients with CKD not requiring RRT, using objective laboratory tests, physical performance measures and self-reported functioning; and (ii) to determine the correlations between these measures of physical functioning and renal function.
Methods: Thirty-two patients with CKD (mean estimated glomerular filtration rate [eGFR] 29.9 +/- 17.0) were recruited for the study. Subjects completed symptom-limited treadmill test (peak oxygen uptake [VO2peak]), physical performance measures (gait speed, sit-to-stand and 6-minute walk) and the SF-36 Health Status Questionnaire (physical functioning scale [PF] and physical composite scale [PCS]). Descriptive and correlational analyses were performed on the data.
Results: VO2peak (O2 17.8 +/- 6.7 ml/kg body weight per minute), physical performance measures and self-reported functioning were reduced compared with sedentary age-predicted norms. Significant correlations were found between VO2peak and all other physical functioning measures; however, only maximal gait speed and PCS correlated significantly with eGFR.
Conclusions: Patients with CKD have reduced physical functioning as measured using objective laboratory tests (VO2peak), physical performance measures and self-reported functioning. Given that low physical functioning predicts outcomes in dialysis patients, interventions to maintain or improve physical functioning are warranted prior to initiation of dialysis.