Disease Severity in Never Smokers, Ex-Smokers, and Current Smokers With Axial Spondyloarthritis: Results From the Scotland Registry for Ankylosing Spondylitis

Objective. To examine the relationship between smoking, smoking cessation, and disease characteristics and quality of life (QoL) in spondyloarthritis. Methods. The Scotland Registry for Ankylosing Spondylitis collects data from clinically diagnosed patients with spondyloarthritis. Clinical data, including Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Bath Ankylosing Spondylitis Functional Index (BASFI) scores, were obtained from medical records. Mailed questionnaires contained information on smoking status and QoL (Ankylosing Spondylitis QoL questionnaire [ASQoL]). Linear and logistic regression were used to quantify the effect of smoking, and smoking cessation, on various disease-specific and QoL outcomes, with adjustments for age, sex, deprivation, education level, and alcohol use. Results are presented as regression coefficients (b) or odds ratios (ORs) with 95% confidence intervals (95% CIs). Results. Data were obtained from 946 participants (73.5% male, mean age 52 years). Current smoking was reported by 22%, and 38% were ex-smokers. Ever smokers had poorer BASDAI (b50.5 [95% CI 0.2, 0.9]) and BASFI scores (b50.8 [95% CI 0.4, 1.2]), and reported worse QoL (ASQoL b51.5 [95% CI 0.7, 2.3]). Compared to current smokers, ex-smokers reported less disease activity (BASDAI b520.5 [95% CI 21.0, 20.04]) and significantly better QoL (ASQoL b521.2 [95% CI 22.3, 20.2]). They also were more likely to have a history of uveitis (OR 2.4 [95% CI 1.5, 3.8]). Conclusion. Smokers with spondyloarthritis experience worse disease than those who are never smokers. However, this study provides new evidence that, among smokers, smoking cessation is associated with lower disease activity and better physical function and QoL. Clinicians should specifically promote smoking cessation as an adjunct to usual therapy in patients with spondyloarthritis.