Psoriasis and arthritis. I. A population study.

In a population survey of 3659 persons aged 20 years or older, no association was found between psoriasis and rheumatoid arthritis. Inflammatory, degenerative and soft tissue rheumatic diseases occurred in 59% of the psoriatics and 46% of the controls. However, the mean number of rheumatological diagnoses in the psoriatics was 1.1 and in the controls 1.3. Features of psoriasis were found in 41 individuals (1.1%). Features of inflammatory arthritis (RA + past-polyarthritis) were established in 5% and 2.2% of the psoriatics and the controls respectively, but this difference is not significant. Because patients with psoriasis have complaints associated with the locomotor system more frequently than non-psoriatic people, it seems likely that the referral rate of the former to special clinics is higher.