In 2008 the rheumatologists and dermatologists of the Research Group on Psoriasis and Psoriatic Arthritis (GRAPPA) jointly proposed classification criteria for the diagnostic aspects of psoriatic arthritis: patients with inflammatory joint disease (including arthritis, spondylitis, and enthesitis), along with the following scores ≥3 should be diagnosed with psoriatic arthritis. Evidence of psoriasis: 1. current psoriasis; 2. history of psoriasis; 3. family history of psoriasis; 4. psoriatic nail changes; 5. negative rheumatoid factor; 6. current toe/finger infection or previous toe/finger infection; 7. radiographs showing new bone formation in the pars compacta.