Increasing occurrence of multiple sclerosis in women is linked with cigarette smoking

Samodzielna Lecznica Centrum w Warszawie

AKTUALN NEUROL 2013, 13 (4), p. 267–274

Introduction: Reasons of increasing multiple sclerosis (MS) occurrence in women are unclear, although infection with Epstein-Barr virus and smoking were taken into consideration. The current study investigates relation between smoking and increasing occurrence of MS in women. Method: The female to male ratio (FMR) in smokers of the general population was correlated to FMR in 10 272 (M – 4367, F – 5905) MS patients, who died in the years 1982–2008 in Poland. The ratio of F:M in expected MS patients, who smoked cigarettes and died over 27 years, was also correlated to FMR in smoking general population. Data concerning deceased MS assemblage was received from the Central Statistical Office and information on prevalence of smoking was obtained from the Centre of Oncology in Warsaw. Correlation test by Pearson and linear regression test were used in the study. Results: Annual FMR in 10 272 MS patients was growing in Poland from 1.12 to 1.37 over the years 1982–2008; correlation coefficient r with calendar year was 0.548, p < 0.01. Significant correlation was found between the gender-specific smoking ratio in the general population and the sex-specific ratio in MS assemblage during 27 years: r = 0.595, p = 0.003. Strong correlation was ascertained between the F:M ratio in smoking general population and expected smokers with MS, who died over 3 decades; r = 0.882, p = 0.01-7. The result corresponded to close link between the F:M ratio in MS assemblage and in expected cohort of smokers with MS: r = 0.809, p = 0.01-5. Noteworthy was significant correlation of FMR in expected MS smokers with calendar year (1982–2008): r = 0.794, p < 0.001. Results indicate that the higher was the F:M ratio in cigarette smoking general population, the more increased was the F:M ratio in MS assemblage. Conclusions: The F:M ratio in MS calculated according to year of death increased significantly over 3 decades in Poland. The increasing occurrence of MS in women showed association with F:M smoking proportion in the general population. Growing occurrence of MS in women was at least in part linked with cigarette smoking.

Keywords: multiple sclerosis, gender ratio, smoking, prevention