Migration status, country of origin and long-term outcomes in multiple sclerosis: a Swedish nationwide study.

Abstract

Multiple sclerosis (MS) shows marked geographic and ethnic variation, but the contribution of migration status and region of origin to long-term outcomes remains uncertain. We aimed to examine disability, cognitive and patient-reported outcomes across these dimensions. We analysed 4008 individuals with incident relapsing-onset MS from two nationwide Swedish case-control studies (2005-2019), with registry-based follow-up through April 2022. Repeated measures of expanded disability status scale (EDSS), symbol digit modalities test (SDMT) and MS impact scale (MSIS-29) were obtained prospectively. Cox regression compared outcomes by migration status (Swedish-born with Swedish parents, first-generation immigrants, Swedish-born with immigrant parent/s) and region of origin (Sweden, Nordic countries, non-Nordic Europe, Middle East and North Africa (MENA) and other). Compared with Swedish-born individuals with Swedish parents, first-generation immigrants had higher risks of confirmed disease worsening (CDW) (HR 1.36, 95% CI 1.18 to 1.56) and reaching EDSS 3 (HR 1.25, 95% CI 1.03 to 1.52), whereas Swedish-born individuals with immigrant parents did not differ from the reference group. By region of origin, participants of MENA origin had higher risks of CDW (HR 1.45, 95% CI 1.15 to 1.82), EDSS 3 (HR 1.46, 95% CI 1.07 to 2.00), EDSS 4 (HR 1.82, 95% CI 1.19 to 2.80), SDMT worsening (HR 1.79, 95% CI 1.26 to 2.51) and MSIS-29 worsening. Within a universal-access health system, first-generation immigration into Sweden was associated with faster disability progression, and MENA origin showed consistent excess risks across disability, cognitive and patient-reported outcomes. The overall pattern points to a combination of migration-related and origin-linked influences on MS progression, supporting early risk stratification and culturally adapted care strategies.