Inaccurate Use of the Upper Extremity Fugl Meyer Negatively Impacts UE Rehabilitation Trial Design: Findings from the ICARE RCT.

Geed, Shashwati; Lane, Christianne J; Nelsen, Monica A; Wolf, Steven L; Winstein, Carolee J; Dromerick, Alexander W

OBJECTIVE Determine the extent to which estimates of sample and effect size in stroke rehabilitation trials can be affected by simple summation of ordinal Upper Extremity Fugl-Meyer (UEFM) items compared to a Rasch-rescaled UEFM. DESIGN Rasch analysis of ICARE Phase III trial data, comparing three upper extremity (UE) motor treatments in stroke survivors enrolled 45.8±22.4 days post-stroke. Participants underwent a structured UE motor training called Accelerated Skill Acquisition Program, usual and customary care, or dose-equivalent care. UEFM data from Baseline, post-intervention, 6, and 12 months were included for analysis. SETTING Outpatient stroke rehabilitation. PARTICIPANTS ICARE participants. INTERVENTIONS N/A MAIN OUTCOME MEASURES: Item difficulties, person abilities, sample size. RESULTS Summed raw UEFM scores, because of their ordinality, measured motor impairment inconsistently across different ranges of stroke severity relative to the rescaled UEFM. In the full ICARE sample (N=361), raw UEFM understated scores relative to rescaled by 7.4 points for the most severely impaired, but overstated scores by up to 8.4 points towards the ceiling. As a result, 50.9% of all UEFM observations showed a residual error greater than 10% of the total UEFM score. Relative to the raw, the rescaled UEFM improved effect size of change in motor impairment between baseline and 1-year (d=0.35). For a hypothetical three-arm trial resembling ICARE, UEFM rescaling reduced required sample size by 32% (n = 108) compared to raw UEFM (n= 159). CONCLUSIONS In UE rehabilitation trials, a rescaled UEFM potentially decreases sample size by 1/3, decreasing costs, duration, and subjects exposed to experimental risks. This benefit is obtained through increased measurement efficiency; reductions in ceiling effects are also possible. These findings apply to ICARE-like trials; confirmatory validation in another Phase III trial is needed.