Background This investigation aimed to determine whether patients presenting to a psoriatic arthritis (PsA) clinic early in the course of the disease had less severe disease at presentation, and whether disease duration at presentation predicts progression of joint damage.

Methods Patients followed prospectively in a specialised clinic were divided into those first seen within 2 years of diagnosis (group 1) and those seen with more than 2 years of disease (group 2). The groups were compared with regard to demographics and disease characteristics at presentation. A multivariate analysis using a negative binomial model was conducted to determine whether patients with early disease had less progression of joint damage.

Results 436 patients were identified in group 1 and 641 patients in group 2. Patients in group 2 were older, had longer duration of psoriasis and PsA, more joint damage and were less likely to be treated with disease-modifying antirheumatic drugs, but had similar level of education and degree of psoriasis severity. After adjusting for age, sex, education level, clinical joint damage at first visit and treatment, group 2 had significantly greater rate of clinical damage progression compared with group 1.

Conclusions Disease progression is more marked in patients presenting with established disease of more than 2 years' duration. These results suggest that patients with PsA should be treated earlier in the course of their disease.