Patients with symptoms and signs compatible with psoriatic arthritis (PsA), with or without psoriasis, have been documented in the Swedish Early Psoriatic Arthritis (SwePsA) register. Our aim was to find markers for disease progression and to evaluate treatments for PsA using these data.
Patients referred to rheumatology outpatient clinics within 2 years of onset were assessed on inclusion and at followup 2 years later. Data collection was performed according to the program for SwePsA, and classification was as described by Moll and Wright and the ClASsification Criteria for Psoriatic ARthritis (CASPAR). Remission was recorded if the patient had no tender or swollen joints and if erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were within the reference range. Patients with early rheumatoid arthritis (RA) recruited from the Swedish Early Rheumatoid Arthritis Register (Ramona) provided comparison data.
One hundred thirty-five patients with PsA according to CASPAR were assessed; 44% were classified as having mono/oligoarthritis and 47% as polyarthritis. Two patients (1%) were in remission initially, and 23 (17%) at followup. Patients with polyarticular disease had the highest inflammatory activity, measured by swollen and tender joint counts, ESR, Health Assessment Questionnaire, and self-assessment by visual analog scale of pain and global disease activity. Dactylitis was associated with radiological findings. Compared with RA patients, they had significantly lower CRP, ESR, and number of swollen joints (p = 0.0003, p = 0.0026, p = 0.0380, respectively) at inclusion, but equal numbers of tender joints and self-assessment of pain and disease activity.
About half the patients had polyarthritis and the other half had mono/oligoarthritis at followup after 2 years. Patients with polyarthritis had the highest inflammatory activity. Apart from ESR, CRP, and swollen joint count, there were no significant differences in activity between RA and polyarticular PsA.