Tobacco smoking and disability progression in multiple sclerosis: United Kingdom cohort study

Abstract

Tobacco smoking has been linked to an increased risk of multiple sclerosis. However, to date, results from the few studies on the impact of smoking on the progression of disability are conflicting. The aim of this study was to investigate the effects of smoking on disability progression and disease severity in a cohort of patients with clinically definite multiple sclerosis. We analysed data from 895 patients (270 male, 625 female), mean age 49 years with mean disease duration 17 years. Forty-nine per cent of the patients were regular smokers at the time of disease onset or at diagnosis (ever-smokers). Average disease severity as measured by multiple sclerosis severity score was greater in ever-smokers, by 0.68 (95% confidence interval: 0.36–1.01). The risk of reaching Expanded Disability Status Scale score milestones of 4 and 6 in ever-smokers compared to never-smokers was 1.34 (95% confidence interval: 1.12–1.60) and 1.25 (95% confidence interval: 1.02–1.51) respectively. Current smokers showed 1.64 (95% confidence interval: 1.33–2.02) and 1.49 (95% confidence interval: 1.18–1.86) times higher risk of reaching Expanded Disability Status Scale scores 4 and 6 compared with non-smokers. Ex-smokers who stopped smoking either before or after the onset of the disease had a significantly lower risk of reaching Expanded Disability Status Scale scores 4 (hazard ratio: 0.65, confidence interval: 0.50–0.83) and 6 (hazard ratio: 0.69, confidence interval: 0.53–0.90) than current smokers, and there was no significant difference between ex-smokers and non-smokers in terms of time to Expanded Disability Status Scale scores 4 or 6. Our data suggest that regular smoking is associated with more severe disease and faster disability progression. In addition, smoking cessation, whether before or after onset of the disease, is associated with a slower progression of disability.

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

“…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). …”

Human Immunodeficiency Virus and Multiple Sclerosis Risk: Probing for a Connection

“…A significant proportion of studies have shown that risk factors such as candidate genes [6,7],smoking [8][9][10], geographic location [11,12], viral infections [13][14][15][16][17], wheat consumption [11,18], dairy product consumption [19,20], fish intake [21], animal fat intake [21], high ultraviolet radiation [22][23][24] and Vitamin D [25][26][27] amplify the risk of developing MS or its progression. They might work in synchrony with other risk factors and genes, thus leading to disease onset.…”

A Review of Vascular Disease Risk Factors and Multiple Sclerosis

“…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.…”