Comparison Between Common Performance-Based Tests and Self-Reports of Physical Function in People With Multiple Sclerosis: Does Sex or Gender Matter?
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OBJECTIVE: To estimate the extent to which sex or gender differences affect the relations between tests of physical performance and self-reports about function in everyday life activities. Ecological validity is an important psychometric property when choosing tests of physical function, because they need to relate to everyday function. In multiple sclerosis (MS), the EQUI scale, modified Canadian Aerobic Fitness Test, grip strength, vertical jump, push-up, partial curl-up, gait speed (comfortable or fast), 6-minute walk test, and 9-hole peg test are commonly used but the extent to which they relate to everyday function is understudied and the extent to which ecological validity of these tests differ between women and men is unknown. DESIGN: A cross-sectional analysis was conducted on a random sample of men and women recruited for a study on the life effect of MS. Correlations between pairs of performance outcome (PerfO) and self-reported outcome (SRO) items pairs of variables with theoretical coherence were calculated and gender effects identified using linear regression. SETTING: Participants were recruited from MS clinic at Montreal Neurological Hospital. PARTICIPANTS: The sample (N=188) consisted of 140 women and 48 men with MS. INTERVENTIONS: Not applicable. RESULTS: The mean age ± SD of the participants was 43±10. Sixty PerfO and SRO items yielded 165 theoretically linked pairs separately for women and men. Of these 330 possible pairs, 77 pairs (23%) had correlations ≥0.8, showing strong support for the link between performance tests and everyday function; 203 pairs provided moderate support (r≥0.5). Thirty-one pairs had a statistically significant interaction with gender with men having higher correlations than women (n=27/31). CONCLUSION: The results support the ecological validity for physical performance tests, particularly balance tests and particularly for men. The observation that many indicators of everyday function derived from SROs were related to physical performance supports the routine use of SROs in clinical practice to guide therapy to meet the needs of clients with MS.