Not simply a matter of psoriatic arthritis: epidemiology of rheumatic diseases in psoriatic patients

This study investigated the occurrence of rheumatic conditions (RCs) in a psoriasis (PSO)-dedicated dermatological clinic. PSO subjects with musculo-skeletal discomfort, and/or carrying signs (articular/systemic, even asymptomatic) of RCs; and/or suffering flares of previously established psoriatic arthritis (PsA) were referred to rheumatologist for evaluation. Laboratory tests/imaging were performed as needed. Categorization adhered to RCs classification endorsed by the Italian Society of Rheumatology. Of the 1,200 psoriatic subjects, 277 (23.1 %) were enrolled (146 females). The mean age was 55.7 years (range 21-81), PSO duration was 13.5 years (range 0-62). Thirty-seven patients (13.4 %) were asymptomatic. On an average, 92 (7.6 %) patients/year were evaluated, of whom 79.4 % naive to rheumatological consultations (NRC). Osteoarthritis (OA) and PsA (isolated or combined) showed the highest prevalence, with 156 (56.3 %) and 110 cases (39.7 %), respectively. Among NRC subjects, the mean PsA annual incidence was 29.5 % (standard error of the mean +/- 5.4 %). Other RCs, isolated or associated with PsA/OA, were diagnosed in 31 cases (11.2 %). Thirty-two subjects (11.5 %) had arthralgias, 20 of whom due to congenital/mechanical disorders, the remaining were unclassifiable. In conclusion, the largest part (88.5 %) of PSO subjects referred to rheumatologist showed some RCs. On annual basis, 29.5 % of naive enrolled patients were diagnosed as PsA.