Epidemiology of multiple sclerosis in Iran: a systematic review.

BACKGROUND There is a wide variation in the prevalence of multiple sclerosis (MS) in different geographical regions and the epidemiology of MS in Iran has been a major topic of concern during the last decade. Several population-based studies have shown a sharp increase in the prevalence and incidence of MS in this region. In this study, for the first time, the aim was to provide a comprehensive review regarding the incidence and prevalence of MS across Iran. METHODS A comprehensive literature search was performed using PubMed, Embase, and Web of Science. We also did a manual search of reference lists from primary articles and relevant reviews. Databases of ongoing research and unpublished literature were also searched. RESULTS A total of 22 relevant studies were reviewed and 11 studies met the inclusion criteria. Incidence data were found in 5 studies and ranged from 0.68 to 9.1/100,000 per year in the Iranian population. Prevalence was reported in all studies and ranged from 5.3 to 74.28/100,000 with the higher prevalence among females (female/male ratio ranged from 1.8 to 3.6). The most prevalent subtype of MS was the relapsing-remitting form (65.8-87.8%). The sensory disturbance was the most initial presentation. CONCLUSION The incidence and prevalence of MS in Iran has been increasing rapidly, especially in females. Future research should focus on determining the epidemiological features of MS in the neglected provinces with different ethnicities. Such an effort along with further research towards improvement of data on previously studied areas can enable a field to be opened up to identify the patterns of MS in varied genetic backgrounds and environments of Iran.