Risk factors of Multiple sclerosis and their Relation with Disease Severity: A Cross-sectional Study from Iran.

BACKGROUND Many risk factors have been investigated in multiple sclerosis (MS); however, few studies have focused on the association between risk factors and the disease severity. The aim of our study was to evaluate the association between some of these risk factors and MS severity in a population sample of Iranian patients. METHODS This cross-sectional study was conducted on 660 patients with MS. In addition to demographic variables, many potential risk factors were recorded. To compare the severity, progression index (PI) was calculated. This index is created by current Expanded Disability Status Scale (EDSS) /disease duration. RESULTS Univariate analysis revealed that active smoking status is related with MS severity. (P-value = 0.012). Furthermore, our findings demonstrated that age at the disease onset [P < 0.001; OR = 1.05 (95% CI: 1.03-1.07)], female gender [P = 0.002; OR = 1.86 (95% CI: 1.24-2.77)] and marital status [P = 0.002; OR = 1.71 (95% CI: 1.21-2.41)] correlated with the severity of MS in the adjusted model. MS severity was observed to be related with high school and academic studies ([P = 0.004; OR = 0.56 (95% CI: 0.38-0.83)], [P = 0.001; OR = 0.52 (95% CI: 0.35-0.78)]) (Primary/secondary school studies are used as reference). Moreover, there was an association between MS severity and occupation (white collar, pink collar) ([P = 0.006; OR = 0.32 (95% CI: 0.14-0.73)], [P = 0.007; OR = 0.47 (95% CI: 0.27-0.81)]) (Student is used as reference). Furthermore, the results showed a significant correlation between vision and motor symptoms as an initial symptom and PI (P = 0.001, P = 0.025). CONCLUSION Due to high cost of MS care and its moderate to severe disability, identification of factors influencing the MS severity is important. Our results demonstrated that the major modifiable factors related with MS severity in Iranian population, some protective and some promotive, were smoking, education, marital status and occupation. Prospective studies on larger scale are needed for further proof of these results.