Prevalence and Incidence of Multiple Sclerosis in Isfahan Province, Iran: A 25-Year Population-Based Study

Objective(s) Latest research suggests that Isfahan province has one of the highest rates of multiple sclerosis (MS) in Iran. Consequently, we have designed this study is to investigate the prevalence and incidence of MS in Isfahan province between 1996 to 2021. Material(s) and Method(s) The prevalence and incidence of MS in Isfahan was calculated annually from 1996 to 2021. For each calendar year, the prevalence was estimated by dividing total number of diagnosed cases of MS at any time by the total number of populations in that year, and the incidence was obtained by dividing the total number of newly diagnosed cases of MS each year by the total number of populations at risk in that year. The annual prevalence and incidence were also calculated based on sex categories. The incidence of MS was also estimated according to age onset categories (early, adult, late and very late onset) for the years 2011 and 2016 (based on the available population data in the census of these years). Poisson regression model was used to compare the trends in prevalence and incidence over time by sex and year. Result(s) A total of 9909 patients with MS between 1996 and 2021 were identified in Isfahan, with a remarkable female predominancy (77.4%) and a mean age of 31.99 ± 9.63 years at the time of the diagnosis. The prevalence of MS increased from 3.033 per 100,000 in 1996 to 183.9 per 100,000 in 2021. When stratified by sex, the prevalence of MS increased from 4.963 per 100,000 to 288.9 per 100,000 and from 1.156 per 100,000 to 81.9 per 100,000 for female and male, respectively. Moreover, 9.43 times increase (from 0.714 to 6.733 per 100,000) in annual incidence of MS was observed from 1996 to 2021. Both prevalence and incidence were higher in women than men over time. furthermore, the results of Poisson regression model for trend test showed that the prevalence (3.84; 95% CI: 3.53-4.17) and incidence (3.55; 95% CI: 2.80-4.50) are generally high among female patients. Conclusion(s) In conclusion, our findings are in line with previous research that proposed Isfahan as the lodestone of diagnosed MS cases in Iran. Further research is called-for to illuminate the exact details underpinning this situation. Latest research suggests that Isfahan province has one of the highest rates of multiple sclerosis (MS) in Iran. Consequently, we have designed this study is to investigate the prevalence and incidence of MS in Isfahan province between 1996 to 2021. The prevalence and incidence of MS in Isfahan was calculated annually from 1996 to 2021. For each calendar year, the prevalence was estimated by dividing total number of diagnosed cases of MS at any time by the total number of populations in that year, and the incidence was obtained by dividing the total number of newly diagnosed cases of MS each year by the total number of populations at risk in that year. The annual prevalence and incidence were also calculated based on sex categories. The incidence of MS was also estimated according to age onset categories (early, adult, late and very late onset) for the years 2011 and 2016 (based on the available population data in the census of these years). Poisson regression model was used to compare the trends in prevalence and incidence over time by sex and year. A total of 9909 patients with MS between 1996 and 2021 were identified in Isfahan, with a remarkable female predominancy (77.4%) and a mean age of 31.99 ± 9.63 years at the time of the diagnosis. The prevalence of MS increased from 3.033 per 100,000 in 1996 to 183.9 per 100,000 in 2021. When stratified by sex, the prevalence of MS increased from 4.963 per 100,000 to 288.9 per 100,000 and from 1.156 per 100,000 to 81.9 per 100,000 for female and male, respectively. Moreover, 9.43 times increase (from 0.714 to 6.733 per 100,000) in annual incidence of MS was observed from 1996 to 2021. Both prevalence and incidence were higher in women than men over time. furthermore, the results of Poisson regression model for trend test showed that the prevalence (3.84; 95% CI: 3.53-4.17) and incidence (3.55; 95% CI: 2.80-4.50) are generally high among female patients. In conclusion, our findings are in line with previous research that proposed Isfahan as the lodestone of diagnosed MS cases in Iran. Further research is called-for to illuminate the exact details underpinning this situation.