A Revised Motor Activity Log Following Rasch Validation (Rasch-Based MAL-18) and Consensus Methods in Chronic Stroke and Multiple Sclerosis

Objectives. To derive a shorter version of the Motor Activity Log Quality-of-Movement Scale (MAL-28) with enhanced content and construct validity. Design. Validation cohort. Setting. Outpatient rehabilitation within an academic laboratory. Participants. Retrospective consecutive sample of 149 community-dwelling adults with chronic mild/moderate upper-extremity hemiparesis caused by stroke or multiple sclerosis (MS). Intervention. Not applicable. Methods. Participants received the MAL-28 at baseline and following upper-extremity rehabilitation. Rasch Measurement Theory informed threshold ordering of scoring categories, tests of fit, differential item functioning, targeting, response dependency, local dependency, and reliability (person separation index [PSI]). Seasoned examiners rated the content validity of each item. Test-retest reliability of the revised scale was calculated. Results. We established content and construct validity for 18 items. The resultant 18-item MAL fit the model (χ² = 77.93; df = 72; P = .30) and targeted the population-that is, minimal floor (12.08%) or ceiling effects (0%), with acceptable reliability (PSI = 0.84) and good test-retest reliability [ICC(1, 1) = 0.86]. The hierarchy of item difficulty was independent of sex, age, affected side, diagnosis, or intervention type used, and there was local dependency in 3 pairs of items. Responses from a subsequent testing session were dependent on the responses from prior testing, indicating response dependency, for which a correction was proposed. Once response dependency was neutralized, there was a 15% greater treatment response. Conclusions. Content and construct validity are established for Rasch-based MAL-18 for chronic stages of stroke and MS. A Rasch-based conversion table enables clinical use of the MAL-18.