Responsiveness of patient-reported outcome measures in multiple sclerosis relapses: the REMS study

Abstract

Objectives: To assess the responsiveness of the three most-used patient-reported multiple sclerosis (MS)-specific questionnaires: the Functional Assessment of MS (FAMS), the MS Impact Scale (MSIS-29), and the 54-item MS Quality of Life (MSQOL-54).

Design: Prospective multicentre longitudinal study on 104 MS patients treated with i.v. steroids for clinical exacerbation.

Methods: Patient-reported data, EDSS score and clinical information were collected at admission and 8 weeks later. ‘Internal’ (distribution-based) responsiveness was assessed by standardized response means (SRM). ‘External’ (anchor-based) responsiveness was assessed by receiver operating characteristic (ROC) curves in relation to corresponding changes in a pre-specified reference measure (anchor). The pre-specified anchor was patients’ self-reported recovery assessed on a five-point Likert scale.

Results: SRM was 0.39 for FAMS, 0.58 for MSIS-29 physical scale, 0.45 for MSIS-29 psychological scale, 0.71 for MSQOL-54 physical health composite, and 0.57 for MSQOL-54 mental health composite. Seventy three patients (70%) reported they had improved; physicians agreed substantially with patient assessments (kappa statistic 0.70, 95% CI 0.54-0.85). Areas under ROC curves differed significantly from 0.50 only for the MSIS-29 and MSQOL-54 scales, where areas ranged from 0.65 (95% CI 0.53-0.76) for the MSIS-29 psychological scale, to 0.70 (95% CI 0.58-0.81) for the MSQOL-54 mental health composite. Areas under ROC curves assessed using a physician-based anchor were similar to the patient-based areas.

Conclusions: The responsiveness of the MS-specific instruments was less than ideal. The MSIS-29 and the MSQOL-54 were significantly more responsive, using both distribution-based and anchor-based approaches, than FAMS, and should be preferred in longitudinal studies.