Novel x-ray score distinguishes psoriatic arthritis from osteoarthritis of the hand

Dr. Bahadur reported that the radiologist reported normal hand radiographs in five patients and, of the remaining 94 sets of left- and right-hand radiographs, the scoring system correctly allocated 100% of images to either PsA, OA, or rheumatoid arthritis (RA).

Of note was that the radiologist correctly identified two patients with nodal hand OA who later developed PsA several years later, and one patient with RA who was initially thought to have PsA.

“The system could be successfully used by nonradiologists,” Dr. Bahadur proposed. There was good agreement between the scoring system results and the clinical diagnosis then used by the trainees, with 88% and 67% of the radiographs correctly matched to the clinical diagnosis by the rheumatology trainees, and 70% for the radiology trainee.

Dr. Bahadur noted that the features that were consistently identified as being different between hand OA and PsA patients were soft tissue changes, such as dactylitis, as well as erosions, new bone formation, and other features such as subchondral surface changes and cysts.