Development of an item bank to measure factual disease and treatment related knowledge of rheumatoid arthritis patients in the treat to target era

Objective: To develop a Disease and treatment associated Knowledge in RA item bank (DataK-RA) based on item response theory. Methods: Initial items were developed from a systematic review. Rheumatology professionals identified relevant content trough a RAND modified Delphi scoring procedure and consensus meeting. RA patients provided additional content trough a focus group. Patients and professionals rated readability, feasibility and comprehensiveness of resulting items. Cross-sectional data were collected to evaluate psychometric properties of the items. Results: Data of 473 patients were used for item reduction and calibration. Twenty items were discarded based on corrected item-total point biserial correlation