Development and Validation of a Social Vulnerability Index for use in Canadians Living with Multiple Sclerosis

Background Social factors influence the health outcomes of individuals with multiple sclerosis (MS). Social vulnerability indices (SVIs) can identify populations at risk of poor outcomes and inform targeted interventions, but no SVI has been developed for people with MS to date. Objective We developed a SVI, which aggregates several measures of social vulnerability into a composite, and assessed its performance. Methods We conducted a national, cross-sectional survey of people with MS in Canada from June 2025-March 2026. We selected social vulnerability factors across demographic, socioeconomic, social capital, and access to healthcare domains and created a composite SVI with scores ranging from 0-1, with 1 being the most vulnerable state. We evaluated the construct and discriminative validity using Spearman's correlations, ANCOVA, and Jonckheere-Terpstra tests for linear associations. Results We included 932 individuals in the SVI. SVI values ranged from 0-0.77, with a median (IQR) of 0.22 (0.14-0.33). Higher SVI scores were associated with worse general health and mental health, and more difficulty visiting friends/relatives and participating in social activities (Spearman's rho=0.32-0.38, p<0.01 for all). The SVI differed by levels of general health, comorbidity count, and Patient-Determined Disease Steps scores (ANCOVA p<0.01 for all). Conclusion The SVI offers a novel, parsimonious way of examining social vulnerability in individuals with MS. A larger sample size may have allowed for the inclusion of more variables in the SVI.