Discordance between tender and swollen joint count as well as patient's and evaluator's global assessment may reduce likelihood of remission in patients with rheumatoid arthritis and psoriatic arthritis: data from the prospective multicentre NOR-DMARD study.

Objective: To investigate the predictive value of discordance between (1) tender and swollen joint count and (2) patient's and evaluator's global assessment on remission in patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA).

Methods: From the prospective, multicentre Norwegian-Disease-Modifying Antirheumatic Drug study, we included patients with RA and PsA starting first-time tumour necrosis factor inhibitors and DMARD-naïve patients starting methotrexate between 2000 and 2012. The predictive value of ΔTSJ (tender minus swollen joint counts) and ΔPEG (patient's minus evaluator's global assessment) on remission was explored in prespecified logistic regression models adjusted for age, sex, disease duration and smoking.

Results: A total of 2735 patients with RA and 1236 patients with PsA were included (mean (SD) age 55.0 (13.5)/48.3 (12.4) years, median(range) disease duration 0.7 (0.0-58.0)/1.3 (0.0-48.3) years, 69.7/48.4% females). Baseline ΔTSJ/ΔPEG reduced the likelihood of achieving DAS28<2.6, SDAI≤3.3, CDAI≤2.8, ACR/EULAR Boolean and DAPSA<4 remission after 3 and 6 months in RA (OR 0.95-0.97, p<0.001/OR 0.96-0.99, p≤0.01) and PsA (OR 0.91-0.94, p≤0.004/OR 0.89-0.99, p≤0.002), except for ΔPEG and 6-month DAS28 remission in PsA.

Conclusions: Discordance between patient's and physician's evaluation of disease activity reflected through ΔTSJ and partly ΔPEG may reduce likelihood of remission in RA and PsA. The findings are relevant for use of the treat-to-target strategy in individual patients.