Review Aims to Demystify PsA for General Practitioners

Psoriatic arthritis is an easy diagnosis to miss, but certain features such a family history of psoriasis, inflamed digits and redness over joints can help physicians make the call. 

These features are red flags that a patient should be referred to a rheumatologist, said Dafna Gladman, a professor of medicine at the University of Toronto and author of a new review of clinical features of psoriatic arthritis in the journal Rheumatic Disease Clinics.

"There are still physicians out there who do not understand what psoriatic arthritis is," Gladman said. "When a patient presents with joint pain, even if [the doctor gets] the information about inflammatory joint pain, they do not ask them whether they have psoriasis or family history of psoriasis."

Rheumatologists typically diagnose psoriatic arthritis using the CASPAR criteria, which stands for Classification Criteria for Psoriatic Arthritis. To be diagnosed, a patient must have an inflammatory joint disease plus at least three of the following: current psoriasis or a personal or family history of psoriasis, psoriatic nail dystrophy, negative rheumatoid factor, dactylitis and radiographic evidence of juxta-articular new-born formation. If the patient has current psoriasis, they only need one of the other symptoms (excluding a personal or family history) to qualify for the diagnosis.

Even seasoned rheumatologists can struggle to correctly diagnose psoriatic arthritis, because rheumatoid arthritis is a more common complaint, Gladman said. But psoriatic arthritis is more common than previously believed. Gladman and her colleagues found an incidence of between 2.8 percent and 3.2 percent each year in patients with preexisting psoriasis. Overall, 30 percent of people with skin psoriasis will progress to psoriatic arthritis at some point. About 10 percent to 12 percent of psoriatic arthritis patients do not have psoriasis, Gladman said.[[{"type":"media","view_mode":"media_crop","fid":"43740","attributes":{"alt":"©lculig/Shuttersstock.com","class":"media-image media-image-right","id":"media_crop_9210561525542","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4827","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"font-size: 13.008px; line-height: 1.538em; float: right;","title":"","typeof":"foaf:Image"}}]]

Excellent treatment options exist, Gladman said, so early diagnosis is crucial to prevent disability and complications, such as cardiovascular disease caused by chronic inflammation.

Psoriatic arthritis is marked by joint pain that worsens with inactivity, Gladman wrote in her review. Patients usually present with joints that are swollen and tender, but not as tender as in rheumatoid arthritis. A common marker of psoriatic arthritis is dactylitis, the inflammation of the entire digit. The fingers appear swollen and red, like sausages. If untreated, dactylitis can lead to reduced range of motion.

Meanwhile, about 48 percent of psoriatic arthritis patients have enthesitis, or inflammation of the insertion points of tendons and ligaments. Skin and nail lesions are another red flag. Some 70 percent of patients with psoriatic arthritis will have skin manifestations first, while another 15 percent experience the onset of joint and skin problems simultaneously, Gladman wrote. As a result, dermatologists are often a first line of defense in recognizing that an autoimmune disorder is at play. 

To make this referral process easier, the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) is developing criteria for dermatologists and general physicians to use in assessing whether a patient needs a rheumatology referral.

"The important thing is that the family doctor, the dermatologist, refer them to a rheumatologist," Gladman said. "Let the rheumatologist make the decision."

References:

1. Gladman, D. Clinical Features and Diagnostic Considerations in Psoriatic Arthritis. Rheum Dis Clin N Am 41 (2015) 569–579. http://dx.doi.org/10.1016/j.rdc.2015.07.003

2. Taylor, W., Gladman, D., Helliwell, P., Marchesoni, A., Mease, P. and Mielants, H. (2006), Classification criteria for psoriatic arthritis: Development of new criteria from a large international study. Arthritis & Rheumatism, 54: 2665–2673. doi: 10.1002/art.21972