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Extended report
The role of methotrexate co-medication in TNF-inhibitor treatment in patients with psoriatic arthritis: results from 440 patients included in the NOR-DMARD study
  1. Karen Minde Fagerli1,
  2. Elisabeth Lie1,
  3. Désirée van der Heijde1,2,
  4. Marte Schrumpf Heiberg1,
  5. Åse Stavland Lexberg3,
  6. Eric Rødevand4,
  7. Synøve Kalstad5,
  8. Knut Mikkelsen6,
  9. Tore K Kvien1
  1. 1Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway
  2. 2Department of Rheumatology, Leiden University Medical Center, Leiden, Netherlands
  3. 3Department of Rheumatology, Vestre Viken, Drammen Hospital, Norway
  4. 4Department of Rheumatology Trondheim, St Olavs Hospital, Norway
  5. 5Department of Rheumatology, University Hospital of Northern Norway, Tromsø, Norway
  6. 6Lillehammer Hospital for Rheumatic Diseases, Lillehammer, Norway
  1. Correspondence to Dr Karen Minde Fagerli, Department of Rheumatology, Diakonhjemmet Hospital, Pb 23, Vinderen, Oslo 0319, Norway; karen.fagerli{at}


Background The role of co-medication with tumour necrosis factor inhibitors (TNFi) is well established in rheumatoid arthritis and ankylosing spondylitis. In psoriatic arthritis (PsA) there is little evidence available on this issue.

Material and methods The analyses were based on data from the Norwegian longitudinal observational study on disease-modifying antirheumatic drugs (NOR-DMARD). Patients with PsA starting their first TNFi, either as monotherapy or with concomitant methotrexate (MTX), were selected. Baseline characteristics, responses after 3, 6 and 12 months, and drug survival were compared between those with and without MTX co-medication. A secondary analysis was performed on patients who had confirmed swollen joints at baseline. Cox regression was used to identify predictors of discontinuation.

Results We included 440 patients, 170 receiving TNFi as monotherapy and 270 receiving concomitant MTX. The groups had similar baseline characteristics, except for number of swollen joints, which was higher in the concomitant MTX group. Responses were similar in the two groups in both analyses. Drug survival analyses revealed a borderline significant difference in favour of patients receiving co-medication (p=0.07), and this was most prominent for patients receiving infliximab (IFX) (p=0.01). In the Cox regression analysis lack of concomitant MTX and current smoking were independent predictors of discontinuation of TNFi.

Conclusions We found similar responses to TNFi in patients with and without concomitant MTX, but drug survival was superior in patients receiving co-medication. The effect of MTX on drug survival was most prominent in patients receiving IFX. Smoking at baseline and use of TNFi as monotherapy were identified as independent predictors of drug discontinuation.

  • TNF-alpha
  • Methotrexate
  • Psoriatic Arthritis

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