Research: Smoking influences susceptibility the world over

Maghzi AH et al. Cigarette Smoking and the Risk of Multiple Sclerosis: A Sibling Case-Control Study in Isfahan, Iran. Neuroepidemiology. 2011;37:238-242

Aims: We aimed to study the smoking habits of multiple sclerosis (MS) patients and their healthy siblings in Isfahan province in Iran.

Methods: MS patients registered with the Isfahan MS society database were compared to their healthy siblings who served as controls. Data regarding the smoking habits of patients and their brothers & sisters (siblings) were collected using a specially designed questionnaire.

Results: There were 1,606 participants with 516 cases and 1,090 controls. After adjustments for age and sex, subjects who were ever-smokers had a significant risk of developing MS [odds ratio (OR) 2.67; 95% confidence interval (CI) 1.70-4.21; p<0.001]. Past smokers (OR 8.83; 95% CI 3.98-19.60; p < 0.001) and current smokers (OR 1.84; 95% CI 1.10-3.10; p = 0.021) had a significant risk for developing MS. Disease progression (current expanded disability status scale/disease duration) was not different between smokers and nonsmokers (0.54 ±0.42 vs. 0.49 ±0.48; p = 0.61).

Conclusion: Using a sibling pair method our data confirm the association between smoking and MS. A degree of confounding due to overmatching between siblings was unavoidable, but any bias would be conservative and should have lessened the effect of smoking.

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CoI: The Author of this study has been a visiting member of Team G