How Dermatologists Can Help Address Gaps in the Diagnosis of Psoriatic Arthritis

Up to 42% of patients with psoriasis may develop psoriatic arthritis (PsA), and 84% of those who do may have had cutaneous symptoms for 12 years preceding PsA onset.¹ Dermatologists clearly have an important role in detecting early signs of PsA, and the overlapping treatment needs of patients often require collaborative care between dermatologists and rheumatologists.² 

Fortunately, communication between the two specialties appears to be satisfactory overall, according to Susan M. Goodman, MD, a rheumatologist at the Hospital for Special Surgery in New York, New York. “In my experience, dermatologists and rheumatologists are very good collaborators and refer quickly and appropriately,” she told Rheumatology Advisor. “Careful screening and early referral to rheumatology has become the norm in patients with psoriasis and PsA,” she said.

Studies have shown, however, that there are still gaps in care that reflect a need for improved coordination and education between the specialties. In a systematic review and meta-analysis published in 2015 in the Journal of the American Academy of Dermatology, researchers at multiple French universities found that 15.5% of patients treated for psoriasis at dermatology clinics had undiagnosed PsA, and a study reported in the same journal in 2013 indicates that rate could be even higher.^3,4 

The authors examined the prevalence of PsA in 949 patients with psoriasis in 34 European and North American dermatology clinics. Patients were first assessed for psoriasis by dermatologists and then for PsA by rheumatologists. The rheumatologists diagnosed 30% of the patients with PsA, and 41% of these patients had been previously undiagnosed. 

“It is known that PsA is frequently under-diagnosed in patients with psoriasis [and those patients may] not receive treatment geared to control of their arthritis quickly,” said Dr Goodman. Delays can arise in part because some dermatologists may be uncomfortable evaluating for or treating PsA, or they may lack adequate training to do so.⁵ 

Even small time lags in diagnosis and treatment can have serious consequences for patients. Researchers have shown that even a 6-month delay in diagnosis between the time of symptom onset to the initial rheumatologist consultation can significantly increase the risk of joint damage and disability.²

Coordination of care is crucial not only for accurate and timely diagnosis of the PsA but also to ensure that the patient’s multifaceted, ongoing treatment needs are adequately addressed by both specialties, which are not always clear-cut.  

“Patients with psoriasis presenting to the dermatologist for management of their skin disease may have joint symptoms related or not to PsA, and similarly arthritic patients presenting to a rheumatologist for the management of PsA may have skin lesions related or not to psoriasis,” noted a panel of Italian dermatologists and rheumatologists in a paper published in 2015 in the Journal of Biological Regulators and Homeostatic Agents.⁶

Additionally, while some treatment options for PsA may benefit both the skin and the joints, others can ease joint symptoms but worsen psoriasis lesions. The most notable of such therapies is systemic steroids, which can, in rare cases, lead to rebound of psoriasis during their use or upon termination.² Such risk may be dose-dependent and unlikely to occur when low doses are used in conjunction with a disease modifying agent, and rebound is most likely to occur when the steroid is tapered off or discontinued without the use of a “backup” treatment.

Rebound risk can be reduced if the patient has a carefully planned taper along with one or more added treatments such as methotrexate, biologic agents, oral retinoid, or phototherapy. “The choice of therapy to ensure that arthritis is adequately treated and skin is under control requires collaboration” between the specialties, says Dr Goodman.

Another rare occurrence that underscores the need for coordination of care is the paradoxical psoriasis activation that can be induced by TNF-α blockers. “The lesions do not always resolve even if the anti-TNF agent is discontinued and typically require additional treatment modalities such as topical steroids, calcipotriol, salicylic acid, narrow-band UVB, methotrexate, acitretin, or cyclosporine for resolution,” according to a 2015 paper by dermatologists at the University of Hawaii and the University of California, San Francisco.²