Differences in the Modified Disablement in the Physically Active Scale in Those With and Without Chronic Ankle Instability.

CONTEXT: The modified disablement in the physically active scale (mDPA) has become a commonly utilized patient-reported outcome instrument (PRO) for physically active patients. However, the factor structure of this instrument has not been verified in individuals with chronic ankle instability (CAI). Furthermore, additional evidence examining the mDPA in individuals with CAI is warranted.

OBJECTIVE: The purpose of this study was to verify the factor structure of the modified Disablement in the Physically Active Scale (mDPA) and compare the physical summary component (PSC) and mental summary component (MSC) in those with and without CAI.

DESIGN: Cross-sectional Setting: Laboratory Participants: A total of 118 CAI and 81 healthy controls from a convenience sample participated.

INTERVENTION: Not applicable.

MAIN OUTCOME MEASURES: All subjects completed the 16-item mDPA which included the PSC and MSC; higher scores represent greater disablement. To examine the model fit of the mDPA, a single-factor and two-factor (PSC and MSC) structure were tested. Group differences were examined with independent t-tests (p≤0.05) and Hedges' g effect sizes (ES).

RESULTS: Model fit indices showed the two-factor structure to possesses adequate fit to the data, χ2 (101)=275.58, p<0.001, CFI=0.91, RMSEA=0.09 (95%CI=0.08, 0.11), SRMR=0.06. All items loaded significantly and in expected directions on respective subscales (λ range=0.59-0.87, all p<0.001). The CAI group reported greater disablement as indicated from PSC (CAI:11.45±8.30, Healthy:0.62±1.80, p<0.001, ES=1.67(95%CI=1.33,1.99)) and MSC (CAI:1.75±2.58, Healthy:0.58±1.46, p<0.001, ES=0.53(95%CI=0.24,0.82)) scores.

CONCLUSION: The two-factor structure of the mDPA was verified. Individuals with CAI reported greater disablement on the PSC compared to healthy controls. The moderate ES on the MSC between groups warrants further investigation. Overall, these results indicate the mDPA is a generic PRO that can be utilized with individuals who have CAI.