Background Different than for rheumatoid arthritis, the potential benefits of conventional synthetic disease modifying drug (csDMARD) co-medication among psoriatic arthritis (PsA) patients receiving tumor necrosis factor inhibitors (TNFi) remain unclear.1
Objectives This study aimed to investigate the role of concomitant csDMARDs on survival of subcutaneous TNFi in Norwegian PsA outpatients between 2000 and 2015.
Methods We included all the PsA patients who initiated first time treatment with adalimumab, etanercept, golimumab and certolizumab in the years 2000–2015 in a Norwegian outpatient clinic. Baseline characteristics and drug survival were compared between patients with and without csDMARD co-medication. The X2 test, independent t-test and Mann-Whitney U test were applied as appropriate for group comparisons. Drug survival was explored by Kaplan-Meier analysis, and patients receiving versus not receiving co-medication were compared using the log rank test. Additional analyses for each of the TNFi were performed. Univariable and multivariable Cox regression analysis were used to identify predictors of discontinuation.
Results Among 371 PsA patients being treated with TNFi, 145 received csDMARD co-medication; 58/118 with etanercept, 48/106 with adalimumab, 21/47 with certolizumab and 18/47 with golimumab, respectively. Mean (SD) age was 54.0 (11.5) years, disease duration 13.1 (9.1) years, years of education 12.9 (3.4), body mass index (BMI) 27.1 (4.3) kg/m2, baseline DAS28 4.1 (1.4), 45.7% were female. Baseline characteristics were similar for patients with and without co-medication, except for a higher percentage of first time TNFi users (67.6%) compared to previous TNFi users (32.4%) in the co-medication group, p=0.001. Drug survival of TNFi was similar for patients receiving versus not receiving concomitant csDMARDs (log rank test p=0,181, figure). In the Cox regression analysis identified predictors for TNFi discontinuation were previous use of TNFi (HR 1.68, 95% CI 1.25–2.26, p<0.001) and TNFi type (p<0.001). Separate analyses for first time TNFi users did not change the primary outcome. Separate analyses for different TNFi types showed similar drug survival with and without co-medication, except for certolizumab for which a trend toward better drug survival with co-medication was seen.
Conclusions In our population of TNFi treated PsA patients, we found similar drug survival for patients with and without csDMARD co-medication. Identified predictors for TNFi discontinuation were previous use of TNFi and TNFi type.
Behrens F et al. Tumour necrosis factor inhibitor monotherapy vs combination with MTX in the treatment of PsA: a systematic review of the literature. Rheumatology. 2015; 54: 915–26.
Disclosure of Interest B. Michelsen: None declared, D. Soldal: None declared, A. Kavanaugh: None declared, D. Boyle: None declared, G. Haugeberg Grant/research support from: Pfizer