Psoriatic arthritis is commonly misdiagnosed because patients may present with symptoms similar to those with other inflammatory and rheumatologic conditions, according to study findings from Drugs.
In addition, patients may not think to mention to their primary care provider the broad range of vague musculoskeletal symptoms that can be prognostic for psoriatic arthritis.
However, routinely screening patients with psoriasis may help identify those with psoriatic arthritis, according to a review article by Philip J. Mease, MD, from the Swedish Medical Center and University of Washington, Seattle.
The most distinguishing clinical features of psoriatic arthritis most often include psoriatic skin lesions and nail dystrophy, dactylitis and enthesitis. X-rays can sometimes reveal juxtaarticular new bone formation and pencil-in-cup deformity, among other unique presentations, but patients with psoriatic arthritis are typically seronegative for rheumatoid factor.
Screening consists of asking about key signs and symptoms of psoriatic arthritis, including experience with morning joint stiffness with a duration longer than 30 minutes, swelling in fingers or toes, or changes to their nails.
In addition to the routine questions, researchers identified several screening tools can aid in diagnosis, including:
- Psoriatic Arthritis Screening and Evaluation (PASE) – A 15-item self-administered questionnaire (82% sensitivity, 73% specificity)
- Psoriatic Arthritis Screening Questionnaire (PASQ) – A 10-item questionnaire with a joint diagram and a self report component
- Psoriasis Epidemiology Screening Tool (PEST) – A five item self-administered questionnaire with a joint diagram (97% sensitivity, 79% specificity)
- Toronto Psoriatic Arthritis Screening (ToPAS) – An 11-item self-administered questionnaire with pictures and a diagram (86.8% sensitivity, 93.1% specificity)
In addition, an electronic version of the PASQ is currently in development, as is the Early Arthritis for Psoriatic Patients (EARP; 82% sensitivity, 91.6% specificity).
A referral to a dermatologist and rheumatologist should be considered if psoriatic arthritis is suspected.
Disclosure: Mease has received grant support and honoraria as a consultant for AbbVie, Amgen, Biogen Idec, Bristol-Myers Squibb, Celgene, Crescendo, Genentech, Janssen, Eli Lilly, Merck, Novartis, Pfizer, UCB and Vertex. He has also received honoraria as a lecturer or member of speakers’ bureau for AbbVie, Amgen, Biogen Idec, Bristol-Myers Squibb, Crescendo, Genentech, Janssen, Eli Lilly, Pfizer and UCB.