Relationship Between Exposure to Dusty Days, Temperature, and Wind Speed and the Prevalence of Multiple Sclerosis in Khuzestan Province, Iran

Abstract

Background: Various factors, including environmental influences, may contribute to the onset of multiple sclerosis (MS). Khuzestan province is notable for being one of the hottest and most dust-storm-affected regions in the Middle East. Objectives: This ecological study aimed to examine the relationship between exposure to dusty days, temperature, and wind speed and the prevalence of MS in cities across Khuzestan province, southern Iran. Methods: This ecological research was conducted in 2019 in Khuzestan province and utilized available data on MS prevalence, dusty days, temperature, and wind speed. The data were obtained from the Khuzestan MS Center database, the Environmental Protection Agency, and the Meteorological Organization of Khuzestan province. A multi-pollutant generalized additive model (GAM) was applied to evaluate the relationship between the independent variables and MS prevalence. Data analysis was performed using R software version 3.4.3. Results: The average age of the patients was 31.40 ± 8.94 years, with a female-to-male sex ratio of 3.05. In 2019, the average annual prevalence of MS across the 27 counties in Khuzestan province was 42 per 100,000 people. The GAM analysis identified a significant positive association between dusty days and MS prevalence [relative risk (RR) = 1.113, 95% CI: 1.090 - 1.137, P < 0.001] and a significant negative association between average wind speed and MS prevalence (RR = 0.999, 95% CI: 0.9990 - 0.9997, P < 0.001). Conclusions: The findings suggest that an increase in dusty days is linked to higher MS prevalence, whereas higher average wind speeds are associated with lower MS prevalence. This study contributes to a deeper understanding of the role of environmental factors in the prevalence of MS and its management.