Background Studies on the impact of smoking among patients with akylosing spondylitis (AS) treated with tumor necrosis factor alpha inhibitor therapy (TNFi) are few.
Objectives To investigate the association between tobacco smoking and disease activity, treatment adherence and treatment responses among patients with AS initiating the first TNFi in routine care.
Methods Observational cohort study based on the Danish nationwide DANBIO registry. Patient inclusion was from year 2000 until January 1st 2014. Kaplan-Meier plots, logistic and Cox regression analyses by smoking status (current/previous/never smoker) were calculated for treatment adherence and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 50%/20mm-response. Additional stratified analyses were performed according to gender and TNFi-subtype.
Results Among 1576 AS patients included in the study, 1425 (90%) had known smoking status (43% current, 40% never and 16% previous smokers). Median follow-up time was 2.02 years (IQR 0.69-5.01). At baseline, current smokers had longer disease duration (4 years (1-12)/2 years (0-10)), higher BASDAI score (61 mm (47-73)/58 mm (44-70)), Bath ankylosing spondylitis function index (BASFI) (53 mm (35-69)/46 mm (31-66)) and Bath ankylosing spondylitis metrology index (BASMI) (40 mm (20-60)/30 mm (10-50)) than never smokers (all p<0.01). Current and previous smokers had shorter treatment adherence than never smokers (current: 2.30 years (1.81-2.79), previous: 2.48 years (1.56-3.40), never: 4.12 years (3.29-4.95), (median (95% CI)), log rank p<0.0001) (Figure). Similar results were found in multivariate analyses (current vs. never smokers, HR 1.41 (1.21-1.65), p<0.001) most pronounced among men. Current smokers had poorer 6 months' BASDAI50%/20mm response rates than never smokers (overall: 42%/58%, men: 43%/50%, women: 31%/54%, all p<0.01). In multivariate analyses, current smokers had lower odds of achieving response than never smokers both overall (OR 0.48 (95% CI 0.35-0.65), p<0.0001) and stratified by gender (both p<0.001) and TNFi drug type (adalimumab 0.45 (0.27-0.76), etanercept 0.24 (0.10-0.61), infliximab 0.57 (0.34-0.95)).
Conclusions In this study of AS patients treated with TNFi in clinical practise, current smokers had poorer baseline patient-reported outcomes, shorter treatment adherence and poorer treatment response compared to never smokers.
Acknowledgements Thank you to all the departments of rheumatology in Denmark for reporting to the DANBIO registry
Disclosure of Interest B. Glintborg: None declared, P. Højgaard: None declared, M. Hetland: None declared, S. Chrysidis: None declared, J. Espesen: None declared, M. Holland-Fischer Consultant for: Roche, Abbvie, Speakers bureau: UCB, MSD, F. Johansen: None declared, J. Jensen: None declared, I. M. Hansen: None declared, T. Hansen: None declared, G. Kollerup Speakers bureau: MSD, N. S. Krogh: None declared, A. G. Loft Consultant for: MSD, AbbVie, Speakers bureau: MSD, Pfizer, AbbVie, T. Lorenzen: None declared, P. Mosborg: None declared, C. Nilsson: None declared, H. Nordin: None declared, S. Oeftiger: None declared, R. Pelck: None declared, C. Rasmussen: None declared, B. Unger: None declared, L. Dreyer: None declared