Background Non-steroidal anti-inflammatory drugs (NSAIDs) are regarded as the cornerstone of conventional therapy in ankylosing spondylitis (AS). TNF-α blocking therapy is available for AS patients who have insufficient response to conventional therapy. However, little is known about concomitant NSAID use during TNF-α blocking therapy.
Objectives The aim of the present study was to evaluate NSAID use in AS patients with and without TNF-α blocking therapy during 2-year follow-up.
Methods The present analysis is part of the GLAS cohort, an ongoing longitudinal observational cohort study in daily clinical practice. Since November 2004, consecutive AS outpatients who started TNF-α blocking therapy because of active disease at the UMCG and the MCL were included. In 2009, this inclusion was extended to all consecutive AS outpatients, irrespective of treatment regimen. All patients fulfilled the modified New York criteria for AS (>90%) or the ASAS criteria for axial spondyloarthritis.
At every follow-up visit, disease activity was assessed using Bath AS disease activity score (BASDAI), AS disease activity score (ASDAS), and C-reactive protein (CRP). NSAID use (yes/no) and type of NSAID were recorded prospectively. In addition, dosage and frequency were assessed retrospectively from clinical records and the recently developed ASAS-NSAID index was calculated. NSAID use during the first 2 years of follow-up was compared between patients with and without TNF-α blocking therapy.
Results Of the 407 included patients, 66% were male, 73% HLA-B27 positive, mean age was 43.5 years (SD ±12.6), and median symptom duration 15 years (range 1-59). These patient characteristics were comparable between patients with (n=270) and without (n=137) TNF-α blocking therapy. As expected, patients who started TNF-α blocking therapy had significantly higher disease activity at baseline (median BASDAI 6.0 vs. 3.6, ASDAS 3.7 vs. 2.3, CRP 12 vs. 4; p<0.001). Disease activity was comparable between both groups after 24 months (median BASDAI 3.0 vs. 4.0, ASDAS 2.0 vs. 2.4, CRP 3 vs. 3; NS).
Of the 270 patients who started TNF-α blocking therapy, 79% used NSAIDs at baseline and this proportion decreased significantly during follow-up; 40% after 12 months (p<0.001) and 38% after 24 months (p<0.001). Of the 137 patients without TNF-α blocking therapy, 73% used NSAIDs at baseline and this proportion remained stable over time; 81% after 12 months (p=0.41) and 78% after 24 months (p=0.61). Similar results were found for the ASAS-NSAID index. NSAID use was comparable between both patient groups at baseline (p=0.18), whereas patients with TNF-α blocking therapy used significantly less NSAIDs after 24 months (p<0.001).
Conclusions In this observational cohort study in daily clinical practice, there was no difference in NSAID use between AS patients with and without indication for starting TNF-α blocking therapy. During TNF-α blocking therapy, the proportion of patients who used concomitant NSAIDs decreased significantly over time. NSAID use remained stable in patients without TNF-α blocking therapy.
Acknowledgements The GLAS cohort was supported by an unrestricted grant from Pfizer. Pfizer had no role in the design, conduct, interpretation, or publication of this study.
Disclosure of Interest M. Carbo: None declared, S. Arends Grant/research support: Abbott, Pfizer, Wyeth, E. Brouwer Grant/research support: Abbott, Pfizer, Wyeth, R. Bos Grant/research support: Pfizer, Consultant for: Pfizer, M. Efde: None declared, M. Leijsma: None declared, H. Bootsma: None declared, E. van der Veer: None declared, A. Spoorenberg Grant/research support: Abbott, Pfizer, Wyeth, Consultant for: Abbvie, Pfizer, UCB