Determining Physical Function Measures for Estimating VO2Peak in Patients Receiving Hemodialysis.

RATIONALE &

OBJECTIVE

Cardiopulmonary exercise testing is the gold standard for evaluating cardiovascular functional capacity, as assessed by oxygen uptake at peak exercise (VO2Peak). Traditional physical function tests have been proposed as predictive of VO2Peak, although their associations remain inconclusive in individuals with kidney failure. This study aimed to assess whether comprehensive physical function metrics are associated with VO2Peak in patients receiving hemodialysis.

STUDY

DESIGN

Cross-sectional analysis from the "Effects of Long Interdialytic Intervals on Cardiovascular Functional Capacity (ECON)" study.

SETTING &

PARTICIPANTS

Thirty patients with kidney failure receiving maintenance thrice-weekly hemodialysis.

PREDICTORS: Physical function tests.

OUTCOMES: VO2Peak (mL·min-1·kg-1) measured by cardiopulmonary exercise testing, with participants dichotomized into Low (n=14) and High (n=16) VO2Peak groups.

ANALYTICAL APPROACH: Group comparisons for demographics and physical function measures were performed. Multivariable linear regression was used to assess associations.

RESULTS

The Low and High groups were well matched by age, sex, and race (all P ≥ 0.05). However, body mass index (32.7 ± 6.7 kg/m2 vs 26.9 ± 6.5 kg/m2; P = 0.02) and fat mass composition (41.8 ± 7.3% vs 28.9 ± 12.0%; P = 0.002) were significantly higher in the Low group. The Short Form-36-Physical Function Scale total score, standing static balance test score, number of sit-to-stands in 30 seconds (30sec-STS), total Short Physical Performance Battery score, Patient-Reported Outcomes Measurement Information System physical function computerized adaptive testing, Patient-Reported Outcomes Measurement Information System physical mobility computerized adaptive testing, handgrip strength, and 6-minute walk test were all significantly associated with VO2Peak (all P < 0.05). However, after adjusting for age, sex, and fat mass composition, only 30sec-STS was significantly associated with VO2Peak (P = 0.04).

LIMITATIONS: The study's small sample size and cross-sectional design limit statistical power and causal inference.

CONCLUSIONS

Metrics of basic physical function demonstrate limited association with VO2Peak in patients on hemodialysis, except for the 30sec-STS test.