Association of Multiple Sclerosis Prevalence With Sociodemographic, Health Systems, and Lifestyle Factors on a National and Regional Level.

Health expenditure per capita is strongly associated with national MS prevalence, suggesting theories that attribute variations in MS prevalence primarily to latitude effects on vitamin D are incomplete. Healthcare access significantly contributes to the global variations in MS prevalence, especially since national wealth rises with latitude and likely results in significant underestimation of MS prevalence in countries with lower health expenditure.