OBJECTIVES: The GRAPPA-OMERACT group has defined the conceptual treatment target and the outcomes to be measured in patients with psoriatic arthritis (PsA), including clinical and patient-reported outcomes (PROs). However, the measurement instruments to gauge treatment effectiveness have not been established. This study aims to reach consensus on the proper measurement instruments to evaluate the effectiveness of biological treatment (BT) for PsA in routine clinical practice.

METHODS: A Delphi questionnaire was developed based on a literature review and 4 discussion groups with patients (n=15) and healthcare professionals (n=18). Four sets of measurement instruments, each including a composite index and a PRO, were proposed (2 for patients with peripheral involvement and 2 for patients with axial involvement). Their suitability (S) and feasibility (F) of use in routine clinical practice were assessed on a seven-point Likert scale (1=completely disagree and 7=completely agree). Consensus was established when at least 75% of the respondents reached agreement (5-7 points) or disagreement (1-3 points). Descriptive statistics were applied.

RESULTS: One hundred and fifteen panelists completed the questionnaire (rheumatologists: 75.7%; dermatologists: 15.7%; nurses 1.7%; hospital pharmacists: 2.6%; clinical psychologists: 1.7%; and healthcare managers: 2.6%).

In PsA patients with peripheral involvement, consensus was reached on the use of either Disease Activity in Psoriatic Arthritis (DAPSA) + Psoriatic Arthritis Impact of Disease (PsAID-12) (S: 91.2%, F: 85.2% agreement) or Minimal Disease Activity (MDA) + PsAID-12 + C-reactive protein (S: 90.5%, F: 76.5%). In PsA patients with axial involvement, consensus was reached on the use of Ankylosing Spondylitis Disease Activity Score (ASDAS) + PsAID-12 (S: 85.3%, F: 76.5%).

CONCLUSIONS: A multidisciplinary consensus has been reached on the most suitable and feasible sets of measurement instruments, including clinical and PRO measures, to assess the effectiveness of BT in PsA patients in the Spanish setting. Further research should explore a therapeutic success definition.