THURSDAY, April 19 (HealthDay News) -- Newer, more expensive medications don't work much better for the chronic inflammatory skin disease known as psoriasis than the standard treatment, a new study indicates.

The researchers found that biologics, which can cost upwards of $10,000 a year, were slightly more effective than a standard drug treatment for psoriasis, methotrexate, but that their impact lessened over time.

The findings provide only limited hope for psoriasis sufferers, who sometimes stop traditional treatments because of nausea and other bad reactions.

"When one looks at the outcome as being clear, or almost clear [skin], the biologics appear to be more effective than methotrexate," said study author Dr. Joel Gelfand. But, when total body surface area affected by the disease is added in that difference diminishes, he said.

The study, published in the April issue of the Archives of Dermatology, was conducted from February 2010 through June 2011 in clinics at the University of Pennsylvania and University of Utah, as well as six private practices around the country. It was designed to look at treatment "in real-world conditions," as opposed to clinical trials, which have showed better results in the past, the study said.

Psoriasis, an autoimmune system disease, causes itchy, scaly, red patches of skin, mostly on the elbows, knees and torso. Moderate to severe rashes afflict about 25 million people worldwide, including 1.4 million people in the United States.

The condition usually emerges in early adulthood, and is associated with elevated risks of cardiovascular disease and early death, according to research cited in the study.

Genetics play an "important role" in who gets psoriasis, said Gelfand, who is also an assistant professor of dermatology and epidemiology at the University of Pennsylvania, noting that environmental factors such as smoking and excess weight have also been linked to the condition.

Some patients find methotrexate and other older medications difficult to tolerate and stop using them because of side effects such as nausea, hair thinning or liver problems, Gelfand explained.

In the research, three biologics and phototherapy were compared with methotrexate, an immunosuppressant also used in cancer treatment.

The study included 713 patients, almost equally divided among men and women, who were rated once for severity of the condition during a regularly scheduled appointment for treatment of psoriasis. Those who had a clear or almost clear skin assessment ranged from 24 percent for methotrexate users to between 34 and 48 percent for the three biologics studied. But, patients on methotrexate had about 3 percent of body surface affected, compared to 2 percent for the biologics, a small difference, said Gelfand.

Biologics can cost $10,000 to $20,000 a year, compared to a couple of thousand dollars for older drugs or phototherapy, said Gelfand.

Phototherapy was found to be about as effective as methotrexate, but is inconvenient because patients must see a doctor three times a week for three months to obtain the recommended dosage, and patients often don't comply with the regimen, Gelfand noted.

On self-assessments, patients found no significant differences among the treatments.

In contrast to the study, another expert on psoriasis said the newer drugs represent a real breakthrough.

Dr. Doris Day, a dermatologist at Lenox Hill Hospital in New York City, said biologics have worked better for many of her patients and have had fewer side effects. The drugs "give patients hope where there was no hope before," she said.

"In an otherwise healthy patient, if the patient has no infections, no TB [tuberculosis] and is not immuno-compromised, the risk with the biologics is low," she said.

Phototherapy poses a risk of skin cancer for fair-skinned people and "you end up with sun-damaged skin and psoriasis," said Day. "Also, psoriasis is a systemic disease, so systemic treatments affect more than just the skin, hopefully keeping people healthier."

She noted that it was important to monitor patients for cardiovascular problems and other conditions, because "it's a pro-inflammatory disease."

More information

To learn more about psoriasis, visit the U.S. National Library of Medicine.