The role of smoking in the development and progression of structural damage in axial SpA patients: A systematic review and meta-analysis

The objective of this study was to determine whether smoking was associated with the cumulative radiographic spinal damage and radiographic progression in patients with ankylosing spondylitis (AS). Thus, we conducted a systematic review and meta-analysis of the available studies to date. An electronic search was conducted from inception to June 21, 2016, in EMBASE, the MEDLINE/PubMed Cochrane Central Register of Controlled Trials databases. Cross-sectional and longitudinal cohort studies investigating the association between smoking and cumulative spinal structural damage or radiographic progression were included. The outcome of interest was the presence of syndesmophytes in cross-sectional studies and radiographic progression in longitudinal studies. The quality assessment was done using the Agency for Healthcare Research and Quality checklist. The authors of potentially relevant studies were contacted regarding the unpublished data. Data from eligible cross-sectional studies were extracted and arranged in a 2x2 table. The odds ratios (ORs) and 95% confidence intervals (CIs) for the dichotomous outcome of interest were computed. The combined data of eight eligible cross-sectional studies for the assessment of association between smoking and cumulative spinal structural damage suggested a significant association (OR, 2.02; 95% CI, 1.51-2.70). No significant heterogeneity was detected between studies (I =23.0%, p=0.25). The heterogeneity of the longitudinal study data did not permit us to undertake a meta-analysis. Hence, a qualitative review was performed. The results of our meta-analysis show that smoking is associated with increased cumulative spinal structural damage in patients with AS. Therefore, rheumatologists should encourage patients with AS to quit smoking.