Dactylitis in psoriatic arthritis: a marker for disease severity?

AIM To describe dactylitis in a large cohort of patients with psoriatic arthritis followed prospectively in a specialist clinic, and identify whether it is associated with a worse prognosis. METHODS Between 1979 and 1999, 537 patients were registered in the psoriatic arthritis clinic and entered onto a longitudinal database. Patients were followed prospectively at six to 12 month intervals according to a standard protocol, and all information was entered onto a database. The database was searched for patients with dactylitis. Descriptive statistics were used to describe the population and chi(2) tests to relate dactylitis to radiographic changes. RESULTS Dactylitis was documented in 260 patients (48%); 69% of the episodes were recorded at presentation to the clinic. Dactylitis affected feet only in 65% of cases, hands only in 24%, and both hands and feet in 12%. Recurrent dactylitis occurred in 44% of the patients. Increased radiological progression was noted in digits showing dactylitis compared with those without dactylitis (50% v 38%, respectively; p<0.0001). CONCLUSIONS Dactylitis is common among patients with psoriatic arthritis. It most often affects the feet, in an asymmetrical distribution. It is associated with a greater degree of radiological damage than occurs in digits not affected by dactylitis.