Waterpipe Tobacco Smoking and Multiple Sclerosis: A Systematic Review and Meta-Analysis

Background: Multiple sclerosis (MS), as an autoimmune disease of the central nervous system, has a significant burden among people worldwide. Tobacco smoking is one of the most prevalent habits of patients with different diseases including those with MS, and among the methods of use, waterpipe tobacco smoking is gaining popularity. Herein, we aimed to systematically evaluate the association between waterpipe smoking and MS. Methods: Relevant studies were identified to be included in this systematic review and meta-analysis through a systematic search in PubMed, Scopus, Web of Science, and Embase. Studies were screened by the title/abstract and then by their full text. Extraction of data was performed for relevant studies. Odds ratios (ORs) and their 95% confidence intervals (CIs) of the association between waterpipe smoking and MS were used to pool the results observed in each study. Results: After the screening, a total of five studies were included in our systematic review, comprised of 3,087 individuals, among which there were 1,135 cases with MS. Random-effect meta-analysis revealed that ever-smoking waterpipe had a significant association with MS (OR: 1.73, 95% CI: 1.38-2.17, p value <0.0001). Similarly, past waterpipe smoking was significantly higher in those with MS, compared with controls (OR: 2.17, 95% CI: 1.61-2.92, p value <0.0001). Based on the reported results, smoking both tobacco and waterpipe had an additive association with MS. Finally, no association was found between the Expanded Disability Status Scale (EDSS) and waterpipe smoking. Conclusion: Waterpipe as one of the common ways of tobacco smoking becoming popular has an association with MS, and even the use of waterpipe for a certain period in the lifetime has a significant correlation with MS. Further large-scale studies are needed to confirm these findings. These results could help clinicians in risk-stratifying the patients and to provide better care for the MS population.