Background/Purpose:

Randomized clinical trials and current recommendations suggest little role for disease-modifying anti-rheumatic drugs (DMARDs) as co-therapy with anti-TNF (aTNF) agents in patients with axial-spondyloarthritis (axSpA), although many physicians continue to prescribe this combination. Our aim was to investigate whether aTNF agents with concomitant DMARDs demonstrate superior clinical efficacy compared with aTNF monotherapy.

Methods:

This is an observational cohort study of all patients in the Swiss Clinical Quality Management (SCQM) registry diagnosed with axSpA by a board-certified rheumatologist. The exposure of interest was use of aTNF monotherapy (mono) versus aTNF in combination with conventional synthetic DMARDs (combo). Exclusion criteria included aTNF initiation > 1 month prior to inclusion in the registry or missing follow-up assessments. The primary outcome was the change in BASDAI at 12 months. Secondary outcome measures were: BASDAI-50, DASDAS, ASDAS-CII and ASDAS-ID. When clinical outcome measures were unavailable at 12 months (+/- 3 months), we used longitudinal interpolation with mixed-effects linear regression to impute missing values. Adjustments were made for potential confounders including age, sex, disease duration, education level, number of prior aTNF agents and calendar year initiation of aTNF.

Results:

We included 1310 axSpA patients with a total of 2236 aTNF treatment courses. The baseline characteristics of the mono and combo groups for all treatment courses are presented in the table. 80.1% were treated with aTNF monotherapy and 19.9% with co-therapy. The predominant DMARDs utilized were methotrexate in 69.7%, sulfasalazine in 19.3% and leflunomide in 9.6%. Disease characteristics were balanced between the 2 groups, with the exception that the co-therapy group was less frequently HLA-B27 positive, was less often ASAS criteria positive and had longer follow-up. DMARD co-therapy was prescribed significantly more often with infliximab and significantly less often with adalimumab and golimumab.

At 12 months follow-up, the mean (SD) reduction in BASDAI was 1.0 (0.8) and the mean reduction in ASDAS-CRP was 0.8 (0.7) for all treatment courses. The mean reductions in BASDAI and ASDAS-CRP for the first aTNF treatment course were 1.4 (1.6) and 1.1 (0.8) respectively. In adjusted analyses, there was no difference in the reduction in BASDAI score between the mono and the combo groups (p=0.65, CI -0.11:0.18). Similarly, there was no statistically significant benefit for DMARD co-therapy with regards to reduction in ASDAS-CRP, BASDAI-50, ASDAS-CII or ASDAS-ID.

Conclusion:

This study of “real-life” patients supports the current recommendation that co-therapy with DMARDs is of no additional benefit compared with aTNF monotherapy in axSpA.

Table:

Baseline characteristics. Unless otherwise stated, the values represent the mean.