Psoriatic arthritis (PSA)--an analysis of 220 patients.

Since 1978, 220 patients with psoriatic arthritis have undergone detailed study at the Women's College Hospital in Toronto, Canada. Clinical, radiological and biochemical data were subjected to computer analysis in order to determine clinical-biochemical correlations within subsets of patients with psoriatic arthritis. Our findings indicate a spectrum of disease patterns and severity. Overall, we found a 40 per cent incidence of deforming, erosive arthropathy, with 17 per cent of patients having five or more deformed joints. ARA stage 3 and 4 radiological joint change occurred in 28 and 14 per cent respectively, and 11 per cent of patients had ARA Class III or IV functional impairment. The asymmetric oligoarthritis previously reported to account for the majority of cases of psoriatic arthritis was not a dominant pattern in our own experience, occurring in only 28 per cent of the series. Polyarthritis was the most common joint pattern, present in 61 per cent with symmetric and asymmetric patterns occurring equally. Our experience suggests that polyarthritis, symmetric or asymmetric, is a more common presentation of the disease than is generally acknowledged. Furthermore, the frequency of deforming destructive arthropathy challenges the concept of psoriatic arthritis as a benign arthropathy.