Does the multiple sclerosis (MS) map need to change again? An update of MS prevalence in Mazandaran province of Iran in 2018

Background Information of Previous studies on the prevalence of MS, including our study conducted 12 years ago, used to shape global prevalence map of MS. According to those results, Iran placed in medium-prevalence MS region in the world Atlas of MS 2013.This study aimed to investigate the prevalence of MS in Mazandaran province after 12 years and the need for possible changes in the global map of the prevalence of MS. Methods We included all MS patients living in Mazandaran province in 2018 in this descriptive cross-sectional study. We updated our pre-existing registration questionnaires which included demographic information and medical data of MS patients by interview. We obtained the demographic profile of Mazandaran province from the most recent census in 2016 and the National Civil Registry of the Mazandaran province for calculating prevalence of MS. Results The total number of MS patients in Mazandaran was 2418 (25.8% male and 74.2% female) with a female to male ratio of 2.9. Based on the local population of 3,332,556, (50.4% male and 49.6% female), this study showed a prevalence of 72.5 per 100,000 for MS in this region. The prevalence of this disease by gender was 37.1 per 100,000 for men and 108.5 per 100,000 for women. The mean (SD) age of the patients at the time of the study was 38.5 (10.1) years with a minimum of 15 and a maximum of 75 years. The most common type of MS was Relapsing-Remitting MS with 86%. Conclusions All recent studies showed significant upward trend in the prevalence of MS around the world. Based on the results of our study and many other studies in Iran, the Atlas of MS prevalence map needs to be update. Iran's status should be changed to the high-prevalence of MS in the new Atlas. Due to the increasing prevalence of MS, we suggest an adjustment in the Global MS Prevalence Scale.