Effect of Smoking Cessation on Multiple Sclerosis Prognosis

Abstract

IMPORTANCE Smoking tobacco is a well-established risk factor for multiple sclerosis (MS), a chronic inflammatory disorder of the central nervous system usually characterized by bouts and remissions and typically followed by a secondary progressive (SP) course. However, it is not clear whether smoking after diagnosis is detrimental. OBJECTIVE To determine whether smoking after MS diagnosis is associated with a change in time to SP disease. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study of patients with prevalent MS who smoked at diagnosis (n = 728) taken from the Genes and Environment in Multiple Sclerosis Study, which consists of patients from the Swedish National MS Registry. The study entrance date was at time of first-year smoking. The study was conducted between November 2008 and December 2011, with patient environmental data collected from November 2009 to March 2011 via questionnaire. Study participants were from all counties in Sweden diagnosed as having MS at the time of the Genes and Environment in Multiple Sclerosis Study and registered in the Swedish National MS Registry. Patients with MS with relapsing-remitting disease course or SP were included. These patients' conditions were diagnosed according to the McDonald criteria and the patients responded to recruitment letters with detailed questionnaires. EXPOSURE Smoking, considered yearly after diagnosis and combined into a time-invariant covariate before diagnosis. MAIN OUTCOMES AND MEASURES Time to SPMS, measured using an accelerated failure time model, with smoking as a time-varying covariate. Other covariates included sex, age at diagnosis, snuff use, and smoking before diagnosis. RESULTS The optimized model illustrated that each additional year of smoking after diagnosis accelerated the time to conversion to SPMS by 4.7% (acceleration factor, 1.047; 95% CI, 1.023-1.072; P < .001). Kaplan-Meier plots demonstrated that those who continued to smoke continuously each year after diagnosis converted to SPMS faster than those who quit smoking, reaching SP disease at 48 and 56 years of age, respectively. CONCLUSIONS AND RELEVANCE This study provides evidence that continued smoking is associated with an acceleration in time to SPMS and that those who quit fare better. Therefore, we propose that patients with MS should be advised to stop smoking once a diagnosis has been made, not only to lessen risks for comorbidities, but also to avoid aggravating MS-related disability.

The lack of association between angiotensin‐converting enzyme gene insertion/deletion polymorphism and nicotine dependence in multiple sclerosis

“…Components of cigarette smoke have been associated with demyelination and axonal degeneration, and nicotine compromises the blood–brain barrier and exerts immunomodulatory action on T‐lymphocytes (Correale & Farez, 2015; Ramanujam et al., 2015; Zhang et al., 2016). In this study, which to our knowledge is the first to address the genetics of nicotine dependence among patients with MS, we investigated whether smoking behavior in MS might be influenced by a functional ACE‐I/D polymorphism that has proved to be relevant in both nicotine dependence and MS (Baghai et al., 2008; Lovrečić et al., 2006; Živković et al., 2016).…”

“…Like other autoimmune disorders, MS is considered to be triggered by environmental factors in individuals with a genetic predisposition, and smoking has been considered one of the most established environmental risk factors for this illness (Mandia et al., 2014; Ramanujam et al., 2015). The relative risk of developing MS among smokers is almost twice that of never‐smokers, and patients with MS who smoke exhibit a more severe disease course and a faster disability progression rate (Correale & Farez, 2015; Fragoso, 2014; Healy et al., 2009; Manouchehrinia et al., 2013; Zhang et al., 2016).…”

“…In line with these findings and according to the evidence suggesting the relevance of RAS in brain dopaminergic signaling (Jenkins et al., 1996, 1997; Obata et al., 2008), in the current work we aimed to investigate whether the ACE‐I/D polymorphic variant might influence smoking behavior among patients with MS. Although the detrimental effects of smoking in MS are well established (Ramanujam et al., 2015; Zhang et al., 2016) and genetics has been proposed to play a substantial role in vulnerability to smoking (Li, 2008), to the best of our knowledge, no studies elucidating the etiology of nicotine dependence in MS have been published.…”

A Review of Vascular Disease Risk Factors and Multiple Sclerosis

“…15,16 Current smokers had significantly worse MS disability at baseline than never-smokers, as measured by the Expanded Disability Severity Scale (EDSS) and MS Severity Scale, as well as a 64% and 34% increased risk of reaching EDSS 4 and 6 compared with non-smokers and former smokers, respectively. Smoking among PwMS has been shown to be associated with decreased whole brain volume and increased T2 lesion volume, increased contrast enhancing lesions, and T1 lesion volume on MRI.…”

“…Smoking among PwMS has been shown to be associated with decreased whole brain volume and increased T2 lesion volume, increased contrast enhancing lesions, and T1 lesion volume on MRI. 15,16,18 More recent findings suggest that smoking cessation has also been associated with a significant decline in the rate of brain volume loss compared with current smokers. 19 Given the high prevalence rates of current smoking among PwMS, interventions aimed at smoking cessation may substantially improve MS-related outcomes and reduce the risk of developing smoking-related comorbidities.…”