The Challenges of Treating Psoriasis

Some 20 percent of patients with skin psoriasis also have psoriatic arthritis, a condition that can often go undiagnosed. That's why a new paper calls for teamwork between dermatologists and rheumatologists to ensure patients get the treatment they need.

A recently released systematic review in the Journal of the American Academy of Dermatology found that as many as 15.5 percent of psoriasis patients had undiagnosed psoriatic arthritis, making dermatologists a first line of defense in recognizing when this disorder is affecting more than the skin. Similarly, in up to 18 percent of cases, psoriatic arthritis precedes skin lesions, suggesting that rheumatologists be aware of how to diagnose the skin form of the disease.

Writing in the journal Clinical and Experimental Rheumatology 2015, dermatologists Vinzenz Oji and Thomas Luger of the University Hospital Münster highlighted the key points that doctors should know about assessing and diagnosing skin psoriasis, focusing on psoriasis vulgaris.

Diagnosing skin psoriasis

Approximately 2 percent of Caucasians have skin psoriasis, identified by salmon-red plaques covered in silvery scales. Some cases, however, are less obvious: In inverse psoriasis, the flexural folds are the only area affected, and the silver scales are usually absent, Oji and Luger wrote. Though psoriasis rarely affects the mucous membranes, the mouth should be examined to rule out other conditions. [[{"type":"media","view_mode":"media_crop","fid":"43710","attributes":{"alt":"©ChristineLangerPueschel/Shutterstock.com","class":"media-image media-image-right","id":"media_crop_5140780257061","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4812","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"}}]]

Between 15 percent and 50 percent of psoriasis patients have nail changes, Oji and Luger wrote. Thus, nail changes are a highly diagnostic sign of skin psoriasis.

Generalized pustular psoriasis (GPP) is characterized by pus-filled eruptions all over the body and is now known to have a different genetic background as psoriasis vulgaris, the researchers wrote. Palmoplantar psoriasis (PPP) is marked by chronic pustules on the hands and feet. Finally, acrodermatitis continua suppurativa involves pustules on the tips of the fingers and the nails.

Assessing plaque psoriasis

There are dozens of scoring systems used to assess the severity of plaque psoriasis, though most include some measure of how much body area is affected. The most validated of these scores, Oji and Luger wrote, is the PASI scale, which stands for Psoriasis Area and Severity Index. This index includes factors such as the amount of skin affected, skin redness (erythema), infiltration and dequamation. Each of these symptoms are assessed on a numerical scale of 0 to 4. These scores are then multiplied by the percent body area affected over the head, trunk, upper extremities and lower extremities.

Nail psoriasis is typically scored with the NAPSI (Nail Psoriasis Severity Index).

Quality of life measures

Health-related quality of life is a key measure for assessing skin psoriasis, the researchers wrote. The PASI does not focus on functional disability, pain or other problems patients might encounter as a result of skin psoriasis. As a result, researchers recommend scales such as the Dermatology Life Quality Index (DLQI), the Short-Form 36 or the Skindex 29 and 17. Each can be filled out by patients in mere minutes.

Patients must also be evaluated for comorbidities, Oji and Luger wrote. The most important is psoriatic arthritis, which is associated with an increased mortality rate due to cardiovascular problems. Because of this cardiovascular involvement, the latest dermatological guidelines call for Body Mass Index or waist circumference measurements in patients with moderate or severe psoriasis.

"Since the coexistence of PsA and skin psoriasis is about 20-30 percent, an early diagnosis of progressive PsA is needed," the researchers wrote. "Management of the patient with psoriasis clearly is the crystallizing point of a rheumatologic-dermatologic team work."

References:

Oji, V. & Luger, T.A. The skin in psoriasis: assessment and challenges. Clin Exp Rheumatol 2015; 33 (Suppl. 93): S14-S19.

ROUZAUD M, SEVRAIN M et al.: Prevalence of undiagnosed psoriatic arthritis among psoriasis patients: Systematic review and meta-analysis. J Am Acad Dermatol 2015; 73: 242-8.