Epidemiological Survey of Multiple Sclerosis in East-Azerbaijan Province , Iran , 2014

Background: Multiple sclerosis (MS) as a chronic disease of the central nervous system have the very prevalent in worldwide. Its epidemiology is different region by region, and most of the geographical and environmental factors may play a role in its incidence. We designed this study to analyze demographic characteristics of MS. Methods: This survey has been conducted in East-Azerbaijan province, northwest of Iran. Prevalence of the MS has been measured using data from Committee for Diagnosis and Treatment of MS in 2014. Age, gender, and type of the disease also had been investigated in this research. Independent T-Test, Chi-square, Pearson and Fisher’s exact test used to analyze data by SPSS21. Results: We had 2774 MS patients in 2014. Of them, 726 (26%) were male and 2003 (73%) were female. The mean age of males and females was 38±9 years and 37.09±9 years, respectively. The mean age of male patients significantly was higher than females (P=0.001). We measured 73.26 prevalence per 100000 populations in East-Azerbaijan province. Conclusion: Prevalence of the MS showed a significant increase in 5 years compared to previous studies. Because of disease’s dishabilitating entity more interventional investigations are recommended to perform in preventing disease incidence or improving the quality of life of sufferers and increasing their life expectancy.


INTRODUCTION
Multiple sclerosis (MS) as one of the chronic diseases attacks central nervous system (CNS) (1).It has an unknown origin, but genetic and immunological factors play a role in the pathophysiology of illness (2).
For the first time, MS was introduced in 1837 by Carswell and Caruneiheir, and then histology of its lesions has been described (3,4).Three years later, clinical diagnosis for MS has been identified by Frerichs (5).Association between histopathological changes and its clinical findings explained for the first time in 1868 (6).

Data Collection
Data of the patients was gathered by researcher made checklist with research variables including, patient demographics, the age of disease onset and clinical form of the disease.Checklists were filled from an electronic database of patients' medical recordings at CDTMS office in Tabriz University of Medical Sciences.

Data Analyses
Data have been entered in SPSS software version 21, and descriptive statistics were used to analyze data (mean, standard deviation, percentage, maximum, minimum, etc.).Independent T-test was performed to compare means.Chisquare was employed by Pearson and Fisher exact tests to compare qualitative parametrical and non-parametrical data, respectively.A p-value less than 0.05 have been considered as significant.

RESULTS
Our study included all MS sufferers up to 2014, and its prevalence was meagered 73.26 per 100000 people.East-Azerbaijan had 3.6 million population, and it had been raised to 3.7 million in our study.
Also, the source of data and inclusion criteria were the same in both studies, the prevalence of the disease showed dramatically increase in 5 years (Figure 1).The frequency of the disease has been raised from 1000 to 2779 (269 to 726 in male and 731 to 2003 in female).Indeed, we had 2774 MS patients in 2014 in East-Azerbaijan.Of them, 726 (26%) were male and 2003 (73%) were female and female to male ratio was 2.76.The mean age of males and female was 38±9 years and 37.09±9 years, respectively.
The mean age in male patients significantly was higher than in females (P=0.001).The mean age of diagnosis in males and female was 30±9 and 29±9 years, respectively.There was a significant difference between mean age of diagnosis in male and female patients (P=0.015).

DISCUSSION
Our result showed that most of MS patients are females and its being diagnosed in 1-2 years earlier in this gender same as other reports (17,18,19,20).The mean age of diagnosis was in the late twenties both in men and women in this study, which was lesser and higher than Qom and Tehran studies, respectively (21)(22).
In spite of geographical features, it could be understood that the disease is diagnosed earlier in more developed regions (23)(24).About 5 percent of patients had early onset of the MS that had been symptomatic for ages younger than sixteen years old.Also, the prevalence of early onset disease was higher in women; it consists lower number of the patients in sum.Our study replicated findings of other investigations that show more incidence of MS in older ages.Female to male ratio was lower than most of other studies conducted in Iran (25)(26)(27).It indicates that gender distribution of the MS is more equipoised in our area compared to other provinces of our country, but it does not degrade more prevalence of MS in females (21,22,28).The mean age of the patients and age of their diagnosis was significantly higher in males than females same as previous studies (15,21,29).The MS was more common (50.04%) in 25-34 years age group than the other age groups.In Saei's report, most of the patients (38%) were between 30 to 35 years age group, but fur- IMMINV 2(2):28-31 ther information has not been mentioned in their article (22).Some environmental and infectious factors have been mentioned as the risk factors such as smoking and Epstein-Barr virus exposure (20).In some other studies correlation of Vit D deficiency and sun exposure with risk of MS has been investigated (30)(31)(32) and reported that Vit D deficiency or lower sunlight exposure in childhood might make people susceptible to MS in adolescence (33).However, the mechanism of these factors in MS pathophysiology is not clearly understood, and additional studies should be performed to evaluate underlying mechanisms (34,35).Unfortunately, in the current study, we could not study risk factors of MS due to some limitations.
In our study, relapsing-remitting MS was the most common type that was similar to other reports (14,21).In 2009, Hashemilar et al. had a survey with the same study method and place and reported MS prevalence was 27.7 per 100000 people in East-Azerbaijan province with the 3.6 million populations according to 2006 national census (15).This increase in MS prevalence in 5 years might have several reasons such as changing in dietary and habitual patterns and developing westernization.If we look optimistically, this significant increase in prevalence can also be due to the improvement of diagnostic methods such as developing magnetic resonance imaging techniques and even overdiagnosis.
Gender distribution of the MS was the same in both surveys, which suggests that regardless of rising prevalence, its growth is balanced.

CONCLUSION
The MS involves young adults that play a major role in developing countries and growing economies.Because of disease's dishabilitating entity more interventional investigations are recommended to perform in preventing disease incidence or improving the quality of life of sufferers and increasing their life expectancy.

Figure 1 .Figure 2 .
Figure 1.Prevalence of MS throught 5 years Figure 2. Education degree of patients (15)00000 populations according to Payamani's study, but 55-98 in 100000 reported by Elhami et al. in Tehran, the capital of Iran (13,14).Hashemilar et al. reported 27.7 in 100000 for the MS in East-Azerbaijan province, northwest of Iran in 2009(15).Neurologists in East-Azerbaijan that diagnose the MS refer their patients to this committee to confirm the diagnosis and patients are being registered after further evaluations and diagnosis approval.All the patients that were registered in