Does cigarette smoking mitigate the severity of skin disease in systemic sclerosis?

Cigarette smoking has significant negative effects on vascular, pulmonary and gastrointestinal outcomes in systemic sclerosis (SSc). The objective of this study was to study the effect of cigarette smoking on the extent of skin disease in SSc. Subjects were patients enrolled in the Canadian Scleroderma Research Group cohort. Smoking history was obtained by patient self-reports. The extent of skin involvement was measured using the modified Rodnan skin score. The effect of smoking on the skin score was assessed using the comprehensive smoking index (CSI), which integrates smoking intensity, duration and time since cessation into a single covariate of smoking effect. The regression model was adjusted for gender, ethnicity and disease duration. This study included 606 SSc patients, of which 87 % were women and 90 % were white; mean disease duration was 11 (±9) years, and mean modified Rodnan skin score was 10 (±9). Of these, 16 % were current, 42 % past and 42 % never smokers. There was a 16 % reduction in skin score (odds ratio 0.84, 95 % confidence interval 0.75, 0.95, p = 0.0029) for every 0.1 unit change in CSI. The effect of smoking on skin disease appeared cumulative and irreversible. Smoking was significantly associated with less extensive skin disease in SSc. This hypothesis-generating study provides new avenues of research, especially insofar as the role of nicotine in SSc is concerned and given that safe nicotine replacement therapy exists.