The association of fatigue and social participation in multiple sclerosis as assessed using two different instruments

Introduction: Fatigue is an important aspect of health-related quality of life and a commonly reported symptom by many persons with multiple sclerosis (MS). There are multiple validated instruments available to assess fatigue in MS with differing benefits for each instrument. Objective: We aimed to assess the relationship between the PROMIS Fatigue instrument and the Fatigue Performance Scale (FPS) in the NARCOMS registry. Additionally, we aimed to examine the association of fatigue with social participation. Methods: The NARCOMS registry is a voluntary, self-report registry, which has enrolled participants with MS who provide semi-annual updates regarding their MS. The Fall 2016 semi-annual survey included the PROMIS Fatigue and Ability to Participate in Social Roles and Activities questionnaires, in addition to demographic and clinical information. We examined the association between instruments using Spearman correlations. Linear and ordinal regression models were used to evaluate associations with fatigue using the PROMIS Fatigue and the FPS. Results: Of the 7,006 Fall 2016 respondents, 6,883 (98.2%) completed the PROMIS instruments. Respondents were mostly female (79.5%) and Caucasian (87.4%), had a mean (SD) age of 59.9 (10.2) years and moderate disability level (median Patient Determined Disease Steps [PDDS] 4 [early cane]). The mean (SD) PROMIS Fatigue T-score was 56.8 (11.0) and median (25th, 75th) FPS was 3 [moderate] (1 [minimal], 4 [severe]). Fatigue measures were strongly correlated (r = 0.83, 95% CI: [0.827, 0.842]). Factors consistently associated with fatigue were PDDS level, depression and pain functionality scales, and symptoms worsening. The ability to participate in social roles and activities was strongly associated with fatigue and had an independent effect on fatigue after adjusting for PDDS, depression and pain levels. Conclusion: A high proportion of respondents experience some level of fatigue and it is independently associated with reduced social participation.