Old measures and new scores in spinal muscular atrophy patients.

INTRODUCTION

A recent Rasch analysis performed on the Hammersmith Functional Motor Scale-Expanded (HFMSE) in patients with spinal muscular atrophy (SMA) identified issues impacting scale validity, redundant items, and disordered thresholds on some items.

METHODS

We modified the HMFSE scoring based on the Rasch analysis and on expert consensus to establish whether the traditional scoring overestimated the number of patients with changes within 2 points from baseline. Data were collected retrospectively from multicenter data sets in 255 type 2 and 3 SMA patients.

RESULTS

The mean 12-month changes using the new and the traditional scoring system did not differ significantly (P > 0.05). The numbers of patients who improved or decreased by >2 points were also similar.

CONCLUSIONS

The presence of outliers using the traditional scoring system was not due to overestimation of changes in activities that were tested bilaterally or to discrepancies in the scoring hierarchy of individual items.