High Prevalence of Psoriatic Arthritis in a Cohort of Patients with Psoriasis Seen in a Dermatology Practice

Background/Objectives: The prevalence of psoriatic arthritis (PsA) is expected to range from 5 to 40% in individuals with psoriasis. The objective of this study was to quantify the prevalence of PsA in psoriasis patients seen in a dermatology practice and to define their characteristics using the validated Psoriatic Arthritis Screening Questionnaire (PASQ). Methods: Patients with definite plaque psoriasis (as determined by a dermatologist) completed the self-administered PASQ tool, and patients with a score >= 7 or >= 9 were assessed by a rheumatologist to ascertain the diagnosis of PsA according to the CASPAR (Classification Criteria for Psoriatic Arthritis) criteria. Results: Using a PASQ cutoff of 7, the estimated prevalence (95% CI) of PsA was 40.9% (29.0-52.8%), whereas a prevalence (95% CI) of 36.4% (24.8-48.0%) was estimated when a PASQ cutoff of 9 was used. Conclusion: Our estimated prevalence of PsA in psoriasis patients from a population of patients drawn from a dermatology practice is greater than most previous estimates. This finding illustrates the importance of screening for PsA in psoriasis patients as this comorbidity may affect the course of treatment and, if left untreated, may have a profound effect on the disability and quality of life of a large number of psoriasis patients.