First Validation of the Full PROMIS Pain Interference and Pain Behavior Item Banks in Patients with Rheumatoid Arthritis.

Pain interference and pain behavior are highly relevant outcomes in patients with rheumatoid arthritis (RA). The Patient-Reported Outcomes Measurement Information System (PROMIS ) is a universally applicable set of item-banks measuring patient-reported health, and, if applied as computerized adaptive tests (CATs), more efficiently and precisely than current instruments. The objective was to study the psychometric properties of the Dutch-Flemish PROMIS Pain Interference (PROMIS-PI) and the PROMIS Pain Behavior (PROMIS-PB) item-banks in patients with RA.2029 patients with RA completed the full PROMIS-PI (V1.1, 40-items) and 1554 patients the full PROMIS-PB (V1.1, 39-items). The following psychometric properties were studied: Unidimensionality, local dependence, monotonicity and Graded Response Model (GRM) fit, cross-cultural validity (Differential Item Functioning [DIF] for language [Dutch vs. Flemish]), other forms of measurement invariance, construct validity, reliability, and floor and ceiling effects.The PROMIS-PI and PROMIS-PB banks were sufficiently unidimensional (Omega-H 0.99,0.95; ECV 0.95,0.78; respectively), had negligible local dependence (0.3%,1.4% of item-pairs), good monotonicity (H 0.75,0.46), and a good GRM model fit (no misfitting items). Furthermore, both item-banks showed good cross-cultural validity (no DIF for language), measurement invariance (no DIF for age, gender, administration mode and disease activity), good construct validity (all hypotheses met), high reliability (>0.90 in the range of patients with RA), and absence of floor and ceiling effects (0% minimum or maximum score, respectively).Both PROMIS-PI and PROMIS-PB banks showed good psychometric properties in patients with RA and can be used as CAT in research and clinical practice.