Multiple sclerosis prevalence and incidence in San Vicente del Raspeig, Spain

Background: Changes in the demographic epidemiology of multiple sclerosis (MS) may challenge the view of a latitudinal gradient in the distribution of MS. The objective of this study was to assess the incidence and prevalence of MS in addition to information on MS phenotypes and the use of disease modifying therapies (DMTs) in San Vicente del Raspeig in south eastern Spain. Methods: This was a prospective epidemiological study of MS in San Vicente del Raspeig (population of 57,175 inhabitants based on the 2017 census) from 2005 to 2018. Multiple sources were used to identify MS cases. We considered as prevalent and incident cases all patients who satisfied either the criteria of Poser for clinically or laboratory-supported definite MS, or McDonald criteria. MS phenotypes were defined according to the 2013 revisions. Results: For the prevalence data, 64 patients were identified. The non-adjusted prevalence was 111.9 (95% CI: 87.7-142.9) cases per 100,000 inhabitants; the prevalence was 159.3 cases per 100,000 inhabitants for women and 63.6 cases per 100,000 inhabitants for men. The female-to-male ratio was 2.6:1. The age-adjusted prevalence for the European standard population was 107 cases per 100,000 inhabitants. During the study period, the incidence was 5 cases per 100,000 inhabitants per year. Most patients were being treated with DMTs (81.3%). MS was active in at least 12.5% of patients. Conclusions: The results are consistent with the increased risk of MS in Spain observed over the last three decades, with growing prevalence rates that place the country in the high-risk prevalence zone.