Assessment of muscle strength and physical performance in patients on maintenance hemodialysis: Before or after the dialysis session?

Abstract

Background and hypothesis

Physical function assessment in patients on hemodialysis is important for identifying and treating functional decreases, which are associated with a worse quality of life and poor outcomes. Some factors, such as fatigue and overhydration, can interfere with functional test results depending on the timing of the assessment. Therefore, we hypothesized the physical function assessment would show different results before and after a hemodialysis session.

Methods

Observational study enrolling adult patients on maintenance hemodialysis. Physical function was assessed by the short physical performance battery, gait speed, timed up and go, sit-to-stand test, and handgrip strength tests. All the tests were performed on the same day before and after the dialysis session. Reproducibility between time points was assessed using the intraclass correlation coefficient. Bland–Altman plots with means of differences and limits of agreement were plotted to evaluate the agreement between time points of each test.

Results

Fifty-four patients were enrolled; 59.3% were male, and the mean age was 58 ± 13 years. The results of all tests were significantly better before the hemodialysis session. The reproducibility between the time points varied from moderate to excellent. However, on the basis of the Bland‒Altman plots, there was no good agreement between the tests before and after hemodialysis time points. In general, the means of differences were low, but the limits of agreement were considered high.

Conclusions

The results of the physical function tests did not agree before and after hemodialysis time points and were better before hemodialysis. Therefore, we suggest that testing should be standardized before hemodialysis sessions.