Measurement properties of motor function measure total score in patients with type 2 and non-ambulatory type 3 SMA, using data from the Phase II olesoxime trial

Abstract

Objective: Motor Function Measure (MFM) is a generic measure designed to monitor function in patients with neuromuscular disorders. It contains 32 items, assessing standing and transfers, and axial, proximal and distal function. Measurement properties of the MFM total score have not previously been assessed in SMA patients. Data, pooled across treatment arms from a Phase II clinical trial in Type 2 and non-ambulatory Type 3 SMA (NCT01302600), were used to evaluate reliability and validity of the MFM. Methods: Internal consistency reliability was assessed using Cronbach's alpha at baseline. Test–retest reliability was assessed using intraclass correlation coefficients (ICC) comparing scores between baseline and Week 26 in a subset of patients rated as “No change” (both clinician-rated and patient-/parent-rated) on Clinical Global Impression scales. Convergent validity was assessed using Spearman rank order correlations with forced vital capacity (FVC) and Hammersmith Functional Motor Scale (HFMS) at baseline/screening. Known-groups validity was assessed using analysis of covariance (controlling for age and gender) comparing HFMS-defined groups (≥median vs. <=“” with=“” patients=“” of=“” the=“” in=“” can=“” 3=“” score=“” a=“” individuals=“” to=“” and=“” is=“” significant=“” 2=“” sma.=“” type=“” non-ambulatory=“” ability=“” function=“” motor=“” assessment=“” reliable=“” valid=“” mfm=“” change.=“” important=“” estimate=“” an=“” as=“” calculated=“” was=“” (sem)=“” 3.54=“” change=“” (ps)