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

LIVERPOOL, ENGLAND – A novel radiologic scoring system differentiated psoriatic arthritis (PsA) from nodal osteoarthritis (OA) of the hand in a pilot study.

“It’s a dilemma that’s faced, perhaps every couple of weeks, by most [rheumatologists]: Is it osteoarthritis or is it early psoriatic arthritis?” said Sardar Bahadur, MD, at the British Society for Rheumatology annual conference.

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Dr. Sardar Bahadur

Both conditions are seen in daily practice, although the prevalence of hand OA is less frequent than knee OA. Approximately one in five of all adults in the United Kingdom have OA and 1%-2% have psoriasis. Of these, the prevalence of hand OA is about 11% and 0.1%-0.3% have psoriatic arthritis.

Being able to differentiate between the two conditions has important consequences for treatment, Dr. Bahadur said.

“Getting the diagnosis wrong could have major implications,” he said. “If you miss psoriatic arthritis, then potentially you are going to find irreversible joint damage causing pain and disability, and the opposite is also true, with misdiagnosis of osteoarthritis, with overuse of immunosuppression and all the cost implications as well as medicolegal consequences.”

Dr. Bahadur of the department of rehabilitation medicine and rheumatology at the Defence Medical Rehabilitation Centre Headley Court, in Epsom, England, added: “So early diagnosis is very important, it means early treatment, it means better care, potentially preventing serious and irreversible damage.”

Together with researchers at Guy’s and St Thomas’ NHS Trust, London, Dr. Bahadur hypothesized that changes in hand x-rays were distinct and could be reliably used to differentiate between the two conditions. They developed a scoring system for hand radiographs that looked at the differences in the interphalangeal joints, soft tissue, and bone features of patients with known OA or PsA.