Patient-reported outcomes and survival in multiple sclerosis: a 10-year retrospective cohort study using the Multiple Sclerosis Impact Scale-29

Abstract

Background There is increasing emphasis on using patient-reported outcomes (PROs) to complement traditional clinical outcomes in medical research, including in multiple sclerosis (MS). Research, particularly in oncology and heart failure, has shown that PROs can be prognostic of hard clinical endpoints such as survival time (time from study entry until death). However, unlike in oncology or cardiology, it is unknown whether PROs are associated with survival time in neurological diseases. The Multiple Sclerosis Impact Scale–29 (MSIS-29) is a PRO sensitive to short-term change in MS, with questions covering both physical and psychological quality of life. This study aimed to investigate whether MSIS-29 scores can be prognostic for survival time in MS, using a large observational cohort of people with MS. Methods and findings From 15 July 2004 onwards, MSIS-29 questionnaires were completed by people with MS registered with the MS Society Tissue Bank (n = 2,126, repeated 1 year later with n = 872 of the original respondents). By 2014, 264 participants (12.4%) had died. Higher baseline MSIS-29 physical (MSIS-29-PHYS) score was associated with reduced survival time (subgroup with highest scores versus subgroup with lowest scores: hazard ratio [HR] 5.7, 95% CI 3.1–10.5, p < 0.001). Higher baseline MSIS-29 psychological score was also associated with reduced survival time (subgroup with highest scores versus subgroup with lowest scores: HR 2.8, 95% CI 1.8–4.4, p < 0.001). In those with high baseline MSIS-29 scores, mortality risk was even greater if the MSIS-29 score worsened over 1 year (HR 2.3, 95% CI 1.2–4.4, p = 0.02). MSIS-29-PHYS scores were associated with survival time independent of age, sex, and patient-reported Expanded Disability Status Scale score in a Cox regression analysis (per 1-SD increase in MSIS-29-PHYS score: HR 1.8, 95% CI 1.1–2.9, p = 0.03). A limitation of the study is that this cohort had high baseline age and disability levels; the prognostic value of MSIS-29 for survival time at earlier disease stages requires further investigation. Conclusions This study reports that PROs can be prognostic for hard clinical outcomes in neurological disease, and supports PROs as a meaningful clinical outcome for use in research and clinical settings.