#ClinicSpeak: is it time to stop smoking?

Smokers with MS do worse than non-smokers? #ClinicSpeak #MSBlog #ResearchSpeak

Yesterday's OMS post generated far fewer comments than I expected. Maybe this was because it was a holiday in most countries and pwMS were doing something else. I was expecting a barrage of criticism. I also challenge you to 'Just, Do It!' and start your own lifestyle/wellness programme. Did you? Here is another challenge; if you are a smoker, 'Please Stop Smoking'

A big issue in MS is smoking and smoking cessation. A large number of pwMS smoke. Smokers on average have a 50% greater chance of getting MS than non-smokers and passive smokers are also at increased risk of getting MS. Why? We don't know but one theory is that cigarette smoke may act as an adjuvant and stimulate the immune system. Another theory is that smoking alter proteins, via a process called post-translational modification, which makes them more antigenic and more likely to stimulate an autoimmune reaction. Interestingly, when you take tobacco as snuff the actual risk of MS drops. Therefore the process of heating and vaporising tobacco must alter some constituent that increases your risk of getting MS. 

Another theory is reverse causation. In other words it is not the smoking that is the risk factor but something associated with smoking. Could smokers be more likely to acquire EBV at a later age, or more likely to get infectious mononucleosis? 

Another important observation that has emerged over the last decade is that pwMS who smoke do worse; they have a more severe MS trajectory. Why? It may be because smoking continues to drive the autoimmune reaction or it may simply act as a co-morbidity and trim brain and cognitive reserve. The cross-sectional survey below suggests that 'smoke-free years' in pwMS are associated with less disability worsening (formerly called progression). The take home message is that if you smoke you should do everything in your power to try and stop smoking. I am aware that this is easier said than done. 

Whose responsibility is it to get pwMS to stop smoking? The neurologist or other MS HCP, the family doctor or GP, a specialist smoking cessation programme, or the pwMS themselves?  It is up to you decide and if you need help ask. A lot can be done to get you to stop smoking and to adhere to it. Good luck. 

Tanasescu et al. Smoking cessation and the reduction of disability progression in Multiple Sclerosis: a cohort study. Nicotine Tob Res. 2017 Apr 10. doi: 10.1093/ntr/ntx084.

BACKGROUND: Smoking is associated with a more severe disease course in people with multiple sclerosis (MS). The magnitude of effect of smoking cessation on MS progression is unknown. The aim of this study was to quantify the impact of smoking cessation on reaching MS disability milestones.

METHODS: This is a cross-sectional study with retrospective reports. A comprehensive smoking questionnaire was sent to 1270 patients with MS registered between 1994 and 2013 in the Nottingham University Hospital MS Clinics database. Demographic and clinical data were extracted from the clinical database. Cox proportional hazard regression was used to estimate effects of smoke-free years on the time to Expanded Disability Status Scale (EDSS) scores 4.0 and 6.0. MS Impact Scale 29 (MSIS-29) and Patient Determined Disease Steps (PDDS) were used to assess the physical and psychological impact of smoking.

RESULTS: Each 'smoke-free year' was associated with 0.96 (95% CI: 0.95 to 0.97) times decreased risk of reaching EDSS 4.0 and 0.97 (95%CI: 0.95 to 0.98) times decreased risk of reaching EDSS 6.0. Non-smokers showed a significantly lower level of disability in all the self-reported outcomes compared with current smokers.

CONCLUSION: The reduction in the risk of disability progression after smoking cessation is significant and time-dependent. The earlier the patients quit, the stronger the reduction in the risk of reaching disability milestones. The quantitative estimates of the impact of smoking cessation on reaching disability milestones in MS can be used in interventional trials.

IMPLICATIONS: This study provides for the first time quantitative estimates of the effects of smoking cessation in MS, essential for informing smoking cessation trials. The clear effect of smoking cessation on MS progression suggests the need to consider adjusting for smoking cessation when assessing for treatment effects in clinical trials of treatments for MS. Smoking cessation should be an early intervention in people with MS.

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