Further characterization and validation of the oxygen uptake efficiency slope for persons with multiple sclerosis

Abstract

Objective: To further characterize the oxygen uptake efficiency slope (OUES) in persons with multiple sclerosis through a direct comparison with matched controls, and by examining differences across the multiple sclerosis disability spectrum. Also, to validate the OUES as an alternative method, which can be derived from submaximal exercise testing, for expressing cardiorespiratory fitness in persons with mild-to-severe multiple sclerosis. Participants: A total of 62 participants (Expanded Disability Status Scale (EDSS)=1.5-6.5) with MS and 21 non-multiple sclerosis controls completed a symptom-limited cardiopulmonary exercise test. Results: The OUES was significantly lower in persons with multiple sclerosis (mean 1,708.5 (standard deviation (SD) 503.7)) compared with non-multiple sclerosis controls (mean 2074.2 (SD 823.2)). With regards to the multiple sclerosis sample, there was a significant difference in the OUES (F[2,59]=8.9, p<0.001, ηρ2=0.23) across the multiple sclerosis disability spectrum. The OUES was significantly correlated with both OUES50 (r=0.86) and OUES75 (r=0.91), and Bland-Altman plots demonstrated agreement between OUES and submaximal OUES values. Conclusion: Overall, the OUES is a viable method for expressing cardiorespiratory fitness in individuals with multiple sclerosis, and submaximal OUES is an appropriate alternative when maximal exercise testing is not feasible.