Multiple sclerosis and related disorders multiple sclerosis across Isfahan Province, Iran: Urban-rural disparities and no association with air quality measures

Abstract

Background Multiple sclerosis (MS) prevalence varies worldwide and appears to be rising in Iran. Environmental factors like air pollution have been hypothesized to contribute to MS risk. This study aimed to map MS prevalence across Isfahan Province and evaluate differences by sex and urban versus rural setting, as well as to assess any association between ambient air pollution and MS prevalence. Methods Data from 11,456 provincially registered MS patients in 28 counties in Isfahan, Iran, were examined in this cross-sectional ecological study. Official population estimates were used to calculate the county-level MS point prevalence per 100,000 population in 2023, stratified by sex. Ratios of females to males were calculated. Annual average PM2.(5) levels for each county were obtained from state sources for the same period. MS prevalence was compared between urban and rural counties, and correlation/regression analyses were used to test associations with pollutant levels. Results and conclusion The prevalence of MS varied widely, ranging from 322.7 in Isfahan County to 15.4 per 100,000 in rural Jarghouyeh. Although there was no significant correlation between the sex disparity and overall prevalence, females were more affected in every county (F/M ratio: 2.0-9.0). Although PM2.(5) levels in Isfahan were extremely high (annual mean=41 mu g/m(3), >8 times the WHO guideline of 5 mu g/m(3)), we found no significant correlation between ambient pollutant concentrations and MS prevalence in the province.