OBJECTIVE: To devise a feasible composite radiographic score for use in observational studies of psoriatic arthritis (PsA).
METHODS: Radiographs from 50 patients with PsA were evaluated with the PsA-modified Sharp, Sharp/van der Heijde (SvdH), and Ratingen scores. Data reductions were made to devise a concise score.
RESULTS: The Reductive X-ray Score for Psoriatic Arthritis (ReXSPA) required the assessment of only 22 joints (117 points), including erosion, joint space narrowing, and osteoproliferation in the hands and feet. The ReXSPA accounted for 80% of change detected with the SvdH score.
CONCLUSION: We report a proof-of-concept radiographic score for observational studies derived though data reduction.