Association of physical function and performance with peak VO2 in elderly patients with end stage kidney disease

Abstract

Background: Physical function is impaired in end stage renal disease (ESRD). Various instruments have been used to assess the functional capabilities and health status of patients with ESRD, but it is not known which has the best association with peak VO₂.

Aims: To assess the association between functional measures in ESRD.

Methods: Thirty nine elderly ESRD patients were evaluated with commonly used functional, health status, and quality of life measures, including maximal cardiopulmonary exercise testing (CPET), 6-min walk (6MWT), sit-to-stand test (STS), Veterans Specific Activity Questionnaire (VSAQ), upper and lower body strength, pulmonary function tests, and body composition determined by dual X-ray absorptiometry. The association between performance on these functional tools, clinical variables, and exercise test responses was assessed, and a non-exercise test multivariate model was developed to predict peak VO₂.

Results: Peak VO₂ was modestly related to VSAQ score (r = 0.59, p < 0.01), indices of upper and lower body strength (r = 0.45, p < 0.01 for both), and FEV₁ (r = 0.51, p < 0.01). Functional and quality of life questionnaires were generally poorly related to one another and to peak VO₂. In a multivariate model, 6MWT performance, forced expiratory volume in 1 s (FEV₁), and VSAQ score were the best predictors of peak VO₂, yielding a multiple R = 0.82, accounting for 67% of the variance in peak VO₂.

Conclusion: Exercise capacity can be reasonably estimated using non-exercise test variables in patients with ESRD, including a symptom questionnaire (VSAQ), 6MWT and FEV₁.

Clinical trial information: ClinicalTrials.gov identifier: NCT01990495. Registered Nov 21, 2013.

Keywords: Exercise testing; Frailty; Oxygen uptake; Physical function; Quality of life.