FRIDAY, Feb. 2 (HealthDay News) -- Many Americans with chronic moderate or severe psoriasis receive no treatment or inadequate treatment, a new survey from the National Psoriasis Foundation (NPF) shows.

The poll also revealed a link between severe psoriasis and low income.

Psoriasis is a non-contagious disease in which the immune system causes skin to grow at an accelerated rate.

The surveys, conducted from 2003 to 2005, found that nearly 40 percent of people with chronic moderate or severe psoriasis were receiving no treatment, and that 57 percent of people with severe psoriasis, and 73 percent of those with moderate psoriasis, were receiving topical treatment only. Over half of patients with moderate to severe psoriasis were not receiving treatment that meets American Academy of Dermatology guidelines.

Those guidelines say that people with chronic moderate to severe psoriasis are candidates for phototherapy or systemic therapy, including biologic agents. However, many of those patients were receiving topical treatment alone, according to the survey data.

"Psoriasis is not a cosmetic disease but rather a chronic inflammation condition that can have a profound negative impact on a person's ability to function," Dr. Mark Lebwohl, chairman of the NPF's medical board, said in a prepared statement. "It's important for patients to openly discuss with their dermatologist how the condition may be impacting them, so that together they can determine the most appropriate treatments."

The survey data also revealed a possible association between psoriasis and low income -- 21 percent of people with severe psoriasis had a low household income (less than $30,000 per year), compared to 13 percent for people with mild psoriasis.

"These are the first data to show a relationship between psoriasis severity and household income," Liz Horn, NPF director of research, said in a prepared statement. "Psoriasis is a serious disease that can significantly affect a person's life by interfering with everyday activities, including work."

The survey findings were to be presented Friday at a meeting of the American Academy of Dermatology in Washington, D.C.

As many as 7.5 million people in the United States have psoriasis, according to the National Institutes of Health.

More information

The U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases has more about psoriasis.