Sharp increase in the incidence and prevalence of multiple sclerosis in Isfahan, Iran

The epidemiology of multiple sclerosis (MS) has changed in recent decades. This study aimed to give an update on the prevalence and incidence of MS in Isfahan, Iran. The study population was all residents of Isfahan province during the period from April 2003 to July 2010. In April 2003, a registry of MS patients was created at the Isfahan MS Society (IMSS), which is the only referral center for MS patients in the province. Nearly all MS patients in Isfahan province are now registered with IMSS and were included in the analysis. Among the 3522 registered patients, 2716 were female and 806 were male (sex ratio: 3.37:1), and 431 were diagnosed in 2009. This results in a prevalence figure of 73.3 (95% CI: 70.9-75.8) and an incidence of 9.1 (95% CI: 8.3-10.0) per 100,000. The reported prevalence and incidence figures in our study were higher than in our previous report of 2007, in which the prevalence and incidence of MS were reported to be 43.8 and 3.64 per 100,000, respectively. This dramatic increase in the prevalence of MS puts Isfahan amongst the regions with the highest prevalence of MS in Asia and Oceania and is mostly due to changing environmental factors, amongst which vitamin D deficiency seems an important factor in our population.