Psoriatic arthritis: Epidemiology, diagnosis, and treatment

Table 1 The classification for psoriatic arthritis criteria[7] for diagnosing psoriatic arthritis-related inflammatory musculoskeletal disease (joint, spine or entheseal)

Evidence of psoriasis (any of three)

Current1: Psoriatic skin or scalp disease present, as judged by a dermatologist or rheumatologist (score of 2)

Personal history: May be obtained from the patient, family doctor, dermatologist, or rheumatologist (score of 1)

Family history: In a first- or second-degree relative, according to patient report (score of 1)

Psoriatic nail dystrophy

Typical psoriatic Nail dystrophy, including onycholysis, pitting, and hyperkeratosis, observed on current physical examination (score of 1)

Negative rheumatoid factor

By any method except latex, but preferably by enzyme-linked immunosorbent assay or nephelometry, according to the local laboratory reference range (score of 1)

Dactylitis

Current: swelling of an entire digit (score of 1)

Personal history: recorded by a rheumatologist (score of 1)

Radiological evidence of juxta-articular new bone formation

Ill-defined ossification near the joint margins (but excluding osteophyte formation) on plain X-rays of the hand or foot (score of 1)

¹Current: Psoriasis score of 2; others: 1. A PsA patient must have inflammatory articular disease with > 3 points from the following 5 categories.