Risk factors of early onset of MS in women in reproductive age period: survival analysis approach

Abstract

The incidence of multiple sclerosis (MS) has doubled in over the last decades in women, whereas it has been almost unchanged in men. The purpose of this study was to investigate the risk factors of early onset multiple sclerosis in women during reproductive years. A retrospective longitudinal study conducted on 200 women aged 15 to 50 years with MS, registered by the MS Society in Isfahan. Data gathering was fulfilled by standard questionnaire including variables about reproductive period, demographic characteristics, and history of diseases. Kaplan-Mayer with log-rank test and Cox regression models were used in predicting of the age of effective factors in onset of MS. P values less than 0.05 were considered statistically significant. The mean age of studied women was 31.77 +/- 8.13 years and the mean and median age of onset the symptoms of MS was 26.79 +/- 7.77 and 26 years, respectively. Based on the cox results occurring menarche at 15 years and higher increase the risk of MS 2.8-fold than those their menarche occurred at 12 years and lower (HR: 2.81, 95 CI; 1.58-4.98).In addition, having only one pregnancy is related to higher risk of MS than other parities and increase the risk of MS 4.5-fold comparing to without parities. Age of menarche and parity numbers was the most important reproductive factors of MS in women. Nevertheless, history of autoimmune diseases, animal bite, childhood disease, family history of MS, regional area (tropical), and living in rural area were not related to early onset of MS.