Smoking and Multiple Sclerosis: A Systematic Review and Meta-Analysis Using the Bradford Hill Criteria for Causation
type: CreativeWork
description: Background. Multiple sclerosis (MS) is one of the most common neurological disorders in the world. However, the cause(s) of MS is unknown. Studies have suggested that smoking may be related to the development and progression of MS. The Bradford Hill criteria are commonly used to assess potentially causal associations. However, to date, no systematic reviews and meta-analyses had used these criteria to comprehensively evaluate the relationship between smoking and MS. The objective of this research was to assess the relationship between smoking and both MS risk and MS progression through a systematic review and meta-analysis, subsequently applying Hill’s criteria to further assess the likelihood of these associations being causal. Methods. Databases including Medline, EMBASE, CINAHL, PsycInfo, and Cochrane Library were searched for relevant studies up until July 28, 2015. A random-effects meta-analysis was conducted for three outcomes: MS risk, conversion from clinically isolated syndrome (CIS) to clinically definite multiple sclerosis (CDMS), and progression from relapsing-remitting multiple sclerosis (RRMS) to secondary-progressive multiple sclerosis (SPMS). Consideration was given to dose-response relationships and risk factor interactions, and discussions of mechanisms and analogous associations presented in the studies. Hill’s criteria were applied to assess causality of the relationships between smoking and each outcome. The effect of second-hand smoke exposure was also briefly reviewed. Results. Smoking had a statistically significant association with both MS risk (conservative: OR/RR 1.54, 95% CI [1.46-1.63]) and SPMS risk (HR 1.80, 95% CI [1.04-3.10]), but the association with progression from CIS to CDMS was non-significant (HR 1.13, 95% CI [0.73-1.76]). Based on Hill’s criteria, there was strong evidence of a causal role of smoking in MS risk, but only moderate evidence of a causal association between smoking and MS progression. Heterogeneity in study desig…
abstract: Background. Multiple sclerosis (MS) is one of the most common neurological disorders in the world. However, the cause(s) of MS is unknown. Studies have suggested that smoking may be related to the development and progression of MS. The Bradford Hill criteria are commonly used to assess potentially causal associations. However, to date, no systematic reviews and meta-analyses had used these criteria to comprehensively evaluate the relationship between smoking and MS. The objective of this research was to assess the relationship between smoking and both MS risk and MS progression through a systematic review and meta-analysis, subsequently applying Hill’s criteria to further assess the likelihood of these associations being causal. Methods. Databases including Medline, EMBASE, CINAHL, PsycInfo, and Cochrane Library were searched for relevant studies up until July 28, 2015. A random-effects meta-analysis was conducted for three outcomes: MS risk, conversion from clinically isolated syndrome (CIS) to clinically definite multiple sclerosis (CDMS), and progression from relapsing-remitting multiple sclerosis (RRMS) to secondary-progressive multiple sclerosis (SPMS). Consideration was given to dose-response relationships and risk factor interactions, and discussions of mechanisms and analogous associations presented in the studies. Hill’s criteria were applied to assess causality of the relationships between smoking and each outcome. The effect of second-hand smoke exposure was also briefly reviewed. Results. Smoking had a statistically significant association with both MS risk (conservative: OR/RR 1.54, 95% CI [1.46-1.63]) and SPMS risk (HR 1.80, 95% CI [1.04-3.10]), but the association with progression from CIS to CDMS was non-significant (HR 1.13, 95% CI [0.73-1.76]). Based on Hill’s criteria, there was strong evidence of a causal role of smoking in MS risk, but only moderate evidence of a causal association between smoking and MS progression. Heterogeneity in study desig…
author: Degelman, Michelle Leigh
language: en
date published: 2017-03
date modified: 2026-07-24T04:03:34Z
provider: University of Regina
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Faculty of Graduate Studies and Research, University of Regina

PropertyValue
property ID: Handle
value: https://hdl.handle.net/10294/7763

PropertyValue
property ID: DOI
value: 10.82465/4209