Background Non-steroidal anti-inflammatory drugs (NSAID's) are the cornerstone of conventional therapy in ankylosing spondylitis (AS). Little is known about concomitant NSAID use in AS patients treated with TNF-α blocking therapy.
Objectives To assess NSAID use in relation to disease activity (ASDAS) in AS patients with and without TNF-α blocking therapy during 2-years of follow-up.
Methods Data were retrieved from the GLAS cohort, an ongoing longitudinal observational cohort study in daily clinical practice in the North of the Netherlands. Since November 2004, consecutive outpatients who started TNF-α blocking and since September 2009 all consecutive outpatients irrespective of treatment regime were included. Patients fulfilled the modified New York criteria for AS (>90%) or the ASAS criteria for axial spondyloarthritis. Follow-up was performed according to a fixed protocol including the assessment of disease activity (ASDAS) and NSAID use. The ASAS-NSAID index was calculated retrospectively from clinical records and stratified for none/very low use versus more regular use (NSAID index <10 and ≥10). The Paired and Independent T test were used for comparison.
Results Of the 404 included patients, 67% was male, 79% HLA-B27 positive, mean age was 44 years (20-80), and median symptom duration 16 years (1-59). All baseline characteristics, were comparable between patients with (n=266) and without (n=135) TNF-α blocking therapy, including NSAID use. As expected, patients who started TNF-α blocking therapy had significantly higher disease activity at baseline (mean ASDAS 3.7 vs. 2.3, p<0.001). In these patients, ASDAS and concomitant NSAID use decreased significantly during follow-up. Patients treated with TNF-α blocking therapy and NSAID index <10 showed significantly lower ASDAS at all follow-up visits then patients with NSAID index ≥10. In patients without TNF-α blocking therapy, NSAID use and ASDAS remained stable over time. ASDAS was significantly lower in patients with NSAID index <10 at baseline and at 24 months of follow-up, but not at 6 and 12 months (table 1).
Conclusions In this observational cohort study, ASDAS and NSAID use decreased rapidly over time in patients with TNF-α blocking therapy. Patients with no to very low NSAID use had lower ASDAS then patients with NSAID use on a more regular basis. In patients without TNF-α blocking therapy, ASDAS and NSAID use remained stable over time and the relationship between ASDAS and NSAID was less clear.
Disclosure of Interest M. Carbo: None declared, S. Arends Grant/research support from: Abbott,Pfizer, Wyeth, E. Brouwer Grant/research support from: Abbott, Pfizer, Wyeth, F. Wink: None declared, M. Efde: None declared, H. Bootsma: None declared, E. van der Veer: None declared, F. Maas: None declared, A. Spoorenberg Grant/research support from: Abbott, Pfizer, Wyeth, Consultant for: Abbvie, Pfizer, UCB