Burden and Disease Characteristics of Patients with Psoriatic Arthritis: A Population-based Cross-sectional Study

Objective. To describe the prevalence and treatment regimes, disease characteristics, and comorbid diseases among patients with psoriatic arthritis (PsA) in Denmark. Methods. All Danish individuals aged >= 18 years with rheumatologist-diagnosed PsA were linked in nationwide administrative registers. Results. Among 4.7 million individuals in Denmark, 10,577 patients with PsA had been diagnosed by a rheumatologist. A female predominance (54.5-59.8%) was seen among patients with PsA, and about half of the patients (53.0%) had received no treatment or treatment only with nonsteroidal antiinflammatory drugs/systemic corticosteroids, while 32.9% had received nonbiological disease-modifying antirheumatic drugs (DMARD) and 14.1% had been treated with biologicals. Cutaneous psoriasis was recorded in 66.2-72.3% of patients with PsA, and patients with severe PsA had the highest prevalences of distal interphalangeal arthropathy, spondylitis, and arthritis mutilans. Smoking and comorbid diseases such as hypertension, diabetes, depression, and anxiety were seen frequently in patients with PsA, but did not significantly differ across severities of PsA. Conclusion. Disease burden appeared to be significant in patients with PsA across all severities. A considerable proportion of patients with PsA did not receive active antipsoriatic treatment, and about 1 out of 3 patients was not diagnosed with psoriasis. Cutaneous symptoms of psoriasis in patients with PsA might be either underreported or undertreated.