Retrospective Cohort Study of Gender Differential in Risk of Multiple Sclerosis in Kuwait

Abstract

Background: Despite an increase in the incidence of multiple sclerosis (MS) in the Middle-East, there is a paucity of published data on sex ratio among MS patients in the region. Therefore, this retrospective cohort study determined sex ratio by year of birth of MS patients born from January 1, 1950, to December 31, 2000, who were diagnosed and registered in the Kuwait National MS Registry till April 30, 2013. Methods: Patients were classified into 5-year periods according to their year of birth. Sex ratio (female:male) and its 95% CI for each period were computed. Using binomial logistic regression, sex ratio in MS patients was modeled with respect to year of birth and nationality. Results: Of 1,035 patients with MS, 675 (65.2%) were women and 798 (77.1%) Kuwaiti. Sex ratio (female:male) of MS cases for entire study period was 1.9 (range 0.4-3.0). Multivariable logistic regression model showed that with each passing year of birth, there was statistically significant 8% increase in sex ratio (female:male) for vulnerability to MS risk (adjusted OR 1.08; 95% CI 1.06-1.09; p < 0.001). Conclusions: There was a statistically significant steady increase on logarithmic scale in the gender disparity for MS risk over the study period. This study from the Middle-East adds to the existing persuasive evidence of enhanced MS risk in women. Further insight in the context of differential risk factors including the role of sex hormones and vitamin D deficiency in MS pathogenesis may help designing preventive strategies.