[A case-control study of the influence of the smoking behaviour in multiple sclerosis]

Several epidemiological studies have demonstrated that there is a genetic factor of susceptibility in Multiple Sclerosis (MS) and that the environmental factors play an important important role in their development. Smoking is among the environment factors studied. In fact, several studies have established a relationship between smoking and multiple sclerosis, although most of them did not find significant results or found that these were contradictory.

To evaluate the influence of the smoking habit on the risk of suffering MS.

This was a case-control matched study with 138 patients diagnosed of MS according to the McDonald criteria who were paired with the same number of controls of the same gender, residents in the same city and having the same age +/-2 years. Demographic data, smoking status (never, always smokers, ex-smokers), Kurtzke disability status scale (EDSS) and type of MS were collected.

Out of a total of 138 MS patients (93 women, 43 men), 110 had relapsing-remitting MS, 20 secondary progressive MS and 7 primary progressive MS. Most of the patients were smokers and ex-smokers (63%). In the control group, only the 41,3% were smokers/ex-smokers. Moreover, the age of onset for smoking was earlier in the case group.

Being a smoker/ex-smoker implies a 27% greater risk of developing MS compared to those who have never smoked. This risk is statistically significant for women but not for men due to the low number of them in the sample.