Psoriatic arthritis: What dermatologists need to know

Seattle - Dermatologists are usually the first specialists to see patients who have psoriasis and who might have psoriatic arthritis. Their decision about how to treat these patients can impact the cutaneous and arthritic manifestations of the disease.

Newer anti-tumor necrosis factor (anti-TNF) agents are worth dermatologists' serious consideration in the treatment of psoriasis patients, according to Philip J. Mease, M.D., clinical professor, University of Washington School of Medicine, Seattle and chief, Division of Rheumatology Clinical Research, Swedish Hospital Medical Center, Seattle. Dr. Mease says that anti-TNF agents, including the already approved etanercept (Enbrel, Amgen), are safer to use chronically than are the old oral gold standards methotrexate and cyclosporine. By using them early in the course of more aggressive psoriatic arthritis, the progressive joint damage may be significantly slowed or possibly stopped. And, most important, studies have shown that the overall effectiveness of the newer agents surpasses traditional oral, topical or light therapies.

More prevalent than thought According to Dr. Mease, the prevailing thought in the 1990s, based on older epidemiologic studies, was that psoriatic arthritis occurred in about 7 percent to 10 percent of patients with psoriasis.

About 85 percent of patients with psoriasis, who ultimately go on to get psoriatic arthritis, will first have skin manifestations of the disease. It is not unusual for 10 years to elapse before symptoms of psoriatic arthritis develop, he says.

Psoriatic arthritis: presentation In psoriatic arthritis, the inflammation not only occurs in joints but also in the enthesis.

"If a person presents with inflammation and pain in enthesial areas of the body, where ligaments insert into ribs, into the bone of the pelvis or the bone around the heel, a physician might dismiss it as a tendon or ligament strain," Dr. Mease says. "It is only when it is chronic and unresponsive to rest and anti-inflammatory therapy that doctors might start to suspect psoriatic arthritis. Sometimes, we see some patients that present with enthesitis and not arthritis."

Anti-TNFs debut Dr. Mease was lead author, conducting the first etanercept trial in the late 1990s in Seattle with a group of 60 patients.

The positive result of using etanercept on both psoriasis and psoriatic arthritis was an eye-opening experience, he says. They published the landmark study in 2000 in The Lancet.

Dr. Mease and colleagues next looked at the impact of etanercept on the progression of psoriatic arthritis, as seen on X-rays.

"One of the ways in which we tell when a new drug is working in a disease like psoriatic arthritis is to determine whether it slows or stops the destructive changes resulting from inflammation, including narrowing of the joint space and erosion of the bone and cartilage in the joint area," he says.

The researchers reported that the anti-TNFs were dramatically slowing and in some cases halting the x-ray progression of joint destruction in those taking them; while those who did not take the medications showed progression of damage on their X-rays. It was the first time, according to Dr. Mease, that a drug had been shown to stop the progressive, destructive changes caused by psoriatic arthritis.

"We had known from a previous study that methotrexate could help joint symptoms and skin changes in patients with psoriasis and psoriatic arthritis, but it did not have significant impact on the X-ray progression of the disease," he says.