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Effect of smoking cessation on multiple sclerosis prognosis
KTH, School of Engineering Sciences (SCI), Mathematics (Dept.). Karolinska Institutet, Sweden.
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2015 (English)In: JAMA Neurology, ISSN 2168-6149, E-ISSN 2168-6157, Vol. 72, no 10, 1117-1123 p.Article in journal (Refereed) PublishedText
Abstract [en]

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 havingMS 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. MAINOUTCOMES ANDMEASURES: 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, wepropose that patients withMS 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.

Place, publisher, year, edition, pages
American Medical Association , 2015. Vol. 72, no 10, 1117-1123 p.
Keyword [en]
adult, age, Article, controlled study, cross-sectional study, female, human, Kaplan Meier method, major clinical study, male, multiple sclerosis, prevalence, priority journal, prognosis, questionnaire, register, sex, smokeless tobacco, smoking, smoking cessation, Sweden
National Category
Neurology
Identifiers
URN: urn:nbn:se:kth:diva-181232DOI: 10.1001/jamaneurol.2015.1788ISI: 000362963000006ScopusID: 2-s2.0-84944069641OAI: oai:DiVA.org:kth-181232DiVA: diva2:902837
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QC 20160212

Available from: 2016-02-12 Created: 2016-01-29 Last updated: 2016-02-12Bibliographically approved

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Ramanujam, Ryan
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Mathematics (Dept.)
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