Validity of Oxygen Uptake Efficiency Slope in patients with multiple sclerosis.

OBJECTIVE To examine the Oxygen Uptake Efficiency Slope (OUES) as an outcome for physical fitness in patients with multiple sclerosis. DESIGN Cross-sectional study. PATIENTS A maximal cycling ergometry test was performed by 56 patients with multiple sclerosis. METHODS The OUES was compared with healthy reference values. Correlation analysis was used to assess the concurrent validity of the OUES and the following commonly used parameters of maximal exercise testing: maximal power output (Wmax) and peak oxygen consumption (VO2peak). The predictive validity of a submaximal OUES, derived using only 50% of the exercise duration (OUES50), and an OUES derived using the full exercise duration (OUES) were determined. RESULTS The OUES (mean 24.2 (standard deviation; SD 7.2)) was markedly lower than previously reported healthy reference values (mean 46.0 (SD 9.0)). Pearson correlation coefficients ranged from 0.514 (p < 0.01) between the OUES and Wmax and 0.857 for VO2peak (p < 0.01). The predictive validity of OUES50 for OUES was 0.918 (p < 0.01). CONCLUSION The moderate to high concurrent validity of the OUES with Wmax and VO2peak and high predictive validity of OUES50 for OUES suggest that maximal exercise testing in patients with low to moderate multiple sclerosis is not necessary.