Psoriatic arthritis can be difficult to diagnose, but a study published in the Journal of the American Academy of Dermatology concluded that detailed questionnaires may help identify patients with the disease.
A randomized study of patients with psoriasis (mean age, 50 years) was conducted by Philip J. Mease, MD, of the Swedish Medical Center and University of Washington School of Medicine, and colleagues, based on rheumatologist assessment.
Three separate PsA screening questionnaires were assessed:
- Psoriasis and Arthritis Screening Questionnaire (PASQ)
- Psoriasis Epidemiology Screening Tool (PEST)
- Toronto Psoriatic Arthritis Screen (ToPAS)
Patients received one of three questionnaires followed by a clinical evaluation from a rheumatologist to confirm diagnosis. The investigators used clinical psoriatic arthritis diagnosis as the standard for comparison and assessed questionnaire accuracy by calculating sensitivity/speciﬁcity and positive/negative predictive values, according to the study data.
Patients were enrolled at 34 dermatology centers in seven European and North American countries: Belgium, Canada, Denmark, France, Germany, Hungary, and the United States and were participants in the Prevalence of Psoriatic Arthritis in Adults with Psoriasis: An Estimate from Dermatology Practice (PREPARE) study.
Of 949 consecutive unselected patients in the study, 285 (30%) received a clinical diagnosis of psoriatic arthritis (95% CI: 27%-33%). Probable psoriatic arthritis was detected in 45.1% of patients using the PASQ test; 43.0% using the PEST test; and 42.9% of patients using ToPAS.
Sensitivity ranged from 0.67 to 0.84; speciﬁcity, 0.64 to 0.75; positive predictive value, 0.43 to 0.60; and negative predictive value, 0.83 to 0.91, according to the study findings.
“The screening tools performed well in identifying patients without psoriatic arthritis and some patients with psoriatic arthritis who would benefit from further assessment by a rheumatologist,” concluded the authors.
“The latter is particularly important because among the 30% of patients with benefit from rheumatologist assessment given a diagnosis of psoriatic arthritis in the PREPARE study, a substantial proportion had not previously received a psoriatic arthritis diagnosis.”
Disclosure: Mease received grant support and/or honoraria for consultations or speaking engagements from Abbott, Amgen, Biogen Idec, Bristol-Myers Squibb, Celgene, Crescendo, Forest, Genentech, Janssen, Lilly, Merck, Novartis, Pfizer Inc, and UCB. Additional researchers also report disclosures.