Background The Multiple Sclerosis International Federation (MSIF) Atlas of MS is the most extensive worldwide study of the epidemiology of MS and the global availability and accessibility of resources for people with MS. Findings from the 2008 and 2013 editions have been widely cited by the global MS research, advocacy, and policy communities.
Objectives To enhance the robustness of worldwide prevalence estimates for MS, confidence indexing and methodology have been introduced to the Atlas of MS third edition.
Methods Between September 2019 and March 2020, country coordinators completed a questionnaire to report the most recent epidemiologic data available about MS in their country. The questionnaire was available in multiple formats and languages (i.e., English, French, and Spanish). Country coordinators provided sources for prevalence, incidence, mean age of onset, and type of disease course. A confidence tool was designed to assess the strength of each data source, rating them as either very low, low, moderate, or high. The factors included in the confidence tool were population size, year of data collection, type of data source, MS diagnostic criteria used, number of sources included, peer-review process, and validation efforts. An estimated MS prevalence was imputed for countries unable to provide a prevalence estimate. These prevalence estimates were developed through a literature review and imputing a prevalence estimate with the Global Health Data Exchange sub-region average.
Results Of 115 reporting countries, 94 (81.7%) countries provided details of the evidence used to obtain the country’s prevalence estimate. Source types included academic papers (61), patient register or cohort (45), government/health service statistics (23), electronic medical records (39), administrative datasets (4), or opinion (39). The prevalence source used for sixty-five percent of countries was rated moderate or high quality. On average, prevalence sources scored higher on the confidence tool than sources providing incidence and other epidemiological data.
Conclusions Using a confidence tool may increase researchers’ ability to interpret epidemiology data and compare findings across countries and regions.