Background/Purpose:

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.

Therefor we aimed to investigate the impact of smoking on disease activity, 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 (including adalimumab, certolizumab, etanercept, golimumab and infliximab) since 2009 from 9 centers in Turkey were included in the analysis.

Treatment response was evaluated as achievement of ÒBASDAI50Ó or ÒASDAS Clinically important improvement (CII)Ó at the 3-monthsÕ and 6 monthsÕ visits. We classified patients as ÔrespondersÕ if they achieved clinical response at the both 3-monthsÕ and 6 monthsÕ 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 (x², Kruskal Wallis and Mann Whitney tests).

Results: Among 561 AS patients analysed (40 % women, mean age:37.9 ± 11), 506 (90 %) had known smoking status. 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 compared with never and previous smokers. Current smokers had male predominance; lower erythrocyte sedimentation rate and higher change in BASMI at 3 months compared with never smokers. HLA status, body mass index, CRP, baseline disease indexes (BASDAI, BASFI, BASMI, ASDAS) and treatment response was not found to be different between current and never smoker patients in our population.  (Table 1).

Treatment adherence was better in previous smokers compared with current smokers but no difference was found between current and never smoker patients (Table 1).

In multivariate analysis, male (OR:1,98; 95% CI (1,39-2,82), p<0,01), HLA positive (OR:1,54; 95%CI (1,08-2,18), p=0,016) and active DMARD user (OR:1,84; (95%CI 1,12-3,01) p=0,015) patients had better treatment response and treatment adherence ((HR:1,93; 95% CI (1,36- 2,73); HR:1,60; 95% CI (1,13-2,27); HR:1,80; 95% CI (1,10-2,95) all p<0,005) but smoking status were not significant (p>0,05).

Conclusion:

This study suggested that smoking might not be associated with disease activity, treatment adherence and treatment response in AS patients treated with TNFi in clinical practice.

Table 1. Baseline demographic and clinical features; and treatment adherence and responses in study groups