The effect of smoking on clinical and structural damage in patients with axial spondyloarthritis: A systematic literature review.

Objectives: To evaluate the association between smoking and clinical parameters and structural damage in axial spondyloarthritis (axSpA).

Methods: We systematically searched MEDLINE, EMBASE and Cochrane Library till November 2015. We selected articles that analysed the smoking impact on disease activity, functional status, structural damage, physical mobility and life quality. Independent extraction of articles by 2 authors using predefined data fields was performed. Studies quality was graded according to the Oxford Level of Evidence scale.

Results: A total of 17 articles were selected for inclusion: 2 case-control, 11 cross-sectional and 4 prospective cohort studies, which analysed 4694 patients. Weak evidence suggested a smoking effect on pain, overall assessment of health, disease activity, physical mobility and life quality in ankylosing spondylitis (AS). Moderate-good evidence revealed higher HAQ-AS among smokers (0.025units/y; 95% CI: 0.0071-0.0429; p = 0.007). Every additional unit of ASDAS resulted in an increase of 1.9 vs. 0.4 mSASSS units/2y in AS smokers vs. non-smokers. Good evidence revealed that cigarette smoking and smoking intensity was associated with spinal radiographic progression in axSpA [mSASSS ≥2 units/2y: OR = 2.75, 95% CI: 1.25-6.05, p=0.012; mSASSS progression in heavy smokers (>10 cigarettes/d): OR = 3.57, 95% IC: 1.33-9.60, p = 0.012].

Conclusions: Published data indicate that smoking has a dose-dependent impact on structural damage progression in axSpA. There is worse HAQ among AS smokers compared to non-smokers. Respect to pain, overall assessment of health, disease activity, physical mobility and life quality, although the evidence level is poor, all evidence points in the same direction: smoking AS patients are worse than non-smoking.