Psoriatic arthritis: interrelationships between skin and joint manifestations related to onset, course and distribution.

To assess the relationships between skin and joint disease, 70 patients with psoriatic arthritis were consecutively evaluated. Data were obtained regarding age, sex, duration of disease, age at onset, and flares of both skin and joint disease. Rheumatological assessment included morning stiffness, number of swollen, tender and deformed joints, involvement of distal interphalangeal joints (DIP), presence of dactylitis, Achilles tendinitis, and clinical lumbar and cervical involvement. Skin assessment included recording of the distribution of skin lesions and nail involvement, and grading of psoriasis severity using the PASI. The scalp was the most frequently involved site. Significant correlation was found between the PASI score and the number of deformed joints and Schober's test. The scalp score was found to correlate with the number of swollen joints, deformed joints, sausage finger and DIP involvement. Synchronous flares of skin and joint were significantly more frequent in the patients with onset of skin and joint diseases within the same year. Likewise, these patients showed a highly significant association between the PASI score and the number of tender, swollen and deformed joints, Schober's test and cervical involvement, whereas no such associations were found among patients with separate onset of skin and joint diseases.