Prevalence of multiple sclerosis in Tuscany at 2011: a study based on validated administrative data

Background Multiple Sclerosis (MS) affects 2.3 million people world-wide. Italy is a high-risk area (with 75,000 cases estimated), with highest rates in the island of Sardinia. The last published rates in Tuscany (central Italy) were a prevalence of 56 cases/100,000 in 1991 and a mortality of 0.4 for males and 0.6 for females in 2002–2006. In Tuscany a population MS register has been founded but, to date, it’s not yet completed. To monitor disease epidemiology, comorbidities and care pathways, but also to describe the disease burden and to plan its prevention, treatment and management strategies and resource allocation, population-based studies are preferable. Administrative data offer a unique opportunity for population-based prevalence study of chronic diseases such as MS. Our aim is to update the prevalence of MS in Tuscany at 12/31/2011 using a validated case-finding algorithm based on administrative data. Methods The prevalence was calculated using administrative data: hospitalization, MS drug dispensing, disease-specific exemptions from patient copayment, home and residential long-term care and inhabitant registry. To test algorithm sensitivity, we used a true-positive reference cohort of MS patients from the Tuscan MS register. To test algorithm specificity, we used a general population cohort of individuals who were presumably not affected by MS. Results At prevalence date, we identified 6,890 cases with a rate of 187.9/100,000 (248.3 in females, 122.3 in males). The sensitivity of algorithm was 98% and the specificity was 99.99%. Conclusions We found a prevalence higher than the data present in literature but it’s similar to the expected rate considering the progressive increment of prevalence due to annual incidence that is higher than annual mortality. Our algorithm can accurately identify patients and this cohort is suitable to monitor care pathways. Our future aim is to create an integrated dataset with administrative and clinical data from MS register. Key messages MS epidemiology in Italy can be regularly and accurately updated through administrative data Prevalence of MS in Italy is increasing over time and we found in Tuscany a rate of 188 cases/100,000