Non-steroidal anti-inflammatory drug use is determined by disease activity in axSpA and decreased by biologicals: a longitudinal analysis.

Objective: To evaluate non-steroidal anti-inflammatory drug (NSAID) use and Assessment in Spondyloarthritis International Society (ASAS)-NSAID scores in patients with axial spondyloarhritis (axSpA) in a longitudinal study.

Methods: In total, 429 patients with axSpA (59% male; 63.6% with AS) were included in this study. Data about disease activity, C-reactive protein (CRP) levels, and NSAID use and dosage were collected at 0, 12, 24, and 52 weeks retrospectively. The relationship with NSAID use /ASAS-NSAID scores and other factors were tested using generalized estimating equations (GEE).

Results: At baseline (0 weeks), 92.8% of patients in biologic disease-modifying anti-rheumatic drugs (bDMARDs) group and 82.1% of patients in conventional treatment group were treated with NSAIDs. At baseline, the proportion (p=0.03) and the median (IQR) ASAS-NSAID scores were higher in bDMARDs group [100 (50) vs 50 (83.4); p<0.001]. During follow-up, NSAID use and ASAS-NSAID scores decreased significantly in patients treated with bDMARDs (p<0.001) and the reduction remained stable throughout the follow-up However, neither NSAID use (p=0.06) nor ASAS-NSAID scores changed in conventional treatment group (p=0.15). In bDMARD-treated patients, ASDAS-CRP and BASFI scores were independent determinants for NSAID use, and BASDAI and PGA were determinants for NSAID dosage. There was no independent significant predictor for ASAS-NSAID scores; PGA was the only significant predictor for NSAID use in the conventional treatment group.

Conclusion: Concurrent biologic treatment was associated with low NSAID intake in patients with axSpA, and NSAID use was determined mainly by disease activity and partly by function during bDMARD treatment.