Prevalence of multiple sclerosis in Sardinia: A systematic cross-sectional multi-source survey

Background: Partial surveys in sub-regions of Sardinia have suggested a high prevalence of multiple sclerosis (MS) on the island, relative to other Mediterranean populations. We assessed the island-wide prevalence of MS and its detailed distribution in Sardinia. Methods: The study population consisted of 5677 MS patients, 1735 men and 3942 women, living in Sardinia. Neurologists retrospectively examined electronic and paper-based records of patients with a diagnosis of MS. The data were then linked to the administrative health information systems. Crude, age-, and sex-specific prevalence estimates of disease were calculated. Results: The overall age-adjusted MS prevalence was 330 per 100,000 (95% confidence interval (CI) 321-338) in individuals older than 15 years, 447 in women (95% CI 433-461), and 205 in men (95% CI 195-214). The prevalence was highest in the Ogliastra and Nuoro districts, respectively, 425 (95% CI 372-478) and 419 (95% CI 387-451), and lowest in the Olbia-Tempio district, 217 (95% CI 195-239). Most cases had relapsing-remitting MS (79.3%), 16.3% had secondary-progressive MS, and 4.4% had primary-progressive MS. Conclusion: These prevalence are among the highest reported so far worldwide. They provide estimates for comparative analyses in other populations and are essential for public health interventions.