The Effect of Smoking on Response to Tumor Necrosis Factor-Alpha Inhibitor Treatment in Ankylosing Spondylitis Patients: Results from the TURKBIO Registry

Background: Although there is good evidence that smoking has a dose-dependent impact on structural damage progression in ankylosing spondylitis (AS) the evidence is poor for its impact on disease activity, physical mobility, life quality and treatment response. Objectives: We aimed to investigate the impact of smoking on disease acitivity, treatment adherence and treatment response in Turkish patients with AS treated with their first tumour necrosis factor-alpha inhibitor (TNFi) therapy in a real-life cohort. Methods: 561 patients fulfilling the modified New York criteria for AS and treated with their first TNFi therapy since 2011 from 8 centers in Turkey were included in the analysis. Treatment response was evaluated as achievement of “BASDAI50” or “ASDAS Clinically important improvement (CII)” at the 3-months’ and 6 months’ visits. Clinical and demographic parameters were compared between current/never and current/previous smoker groups. Demographic and descriptive data are presented by medians/interquartile ranges (IQRs). Groups were compared by non- parametric tests (x 2 , Kruskal Wallis and Mann Whitney tests). Kaplan Meier plots, Cox and logistic regression analyses were calculated for treatment adherence and treatment response. Results: Among 561 AS patients included in the study, 506 (90%) had known smoking status (37% current, 35% never, 17% previous smokers). The median follow-up time was 1.9 years (IQR 0.85–3.5) and disease duration was 3.1 years (0,6–7,7). At baseline, current smokers were younger (34, IQR 29–41) compared with never (38, IQR 30–46 p=0.007) and previous smokers (42, IQR 34–49 p 0,05). Conclusions: In this study of TNFi-treated AS patients in clinical practice, smoking was not found to be associated with disease activity, treatment response and treatment adherence. Disclosure of Interest: None declared