People with psoriasis may have an elevated risk of heart attacks, researchers report today in the Journal of the American Medical Assn.
In recent years, a succession of studies has shown that psoriasis -- a chronic, inflammatory skin condition marked by reddish lesions that can become covered with silvery scales -- is triggered by an immune system gone awry.
It is estimated that the disorder affects 2% to 3% of the U.S. population.
About 150,000 new cases are diagnosed annually.
"We've known for only about 15 years that psoriasis is driven by the immune system," said Dr. Joel Gelfand, lead investigator in a research project that is among the vanguard linking psoriasis with coronary artery disease.
His research reveals how the underlying biology of the disorder is intimately associated with that which leads to clogged arteries and heart attacks.
The hope is to measure levels of C-reactive protein or CRP, a marker in the blood, to determine risk.
Gelfand, an assistant professor of dermatology at the University of Pennsylvania, says an aggressive immune system response, led by turncoat cells and proteins, attacks the skin in psoriasis, causing inflammation.
The patchy skin lesions are a visible sign of that inflammation.
Internally, however, there is probably deeper evidence within the walls of the coronary arteries, which become inflamed and obstructed with cellular debris.
"I think this is really an evolving scientific theory," added Gelfand, "that coronary artery disease and psoriasis share very similar immune pathways."
Using data collected on 600,000 patients in Britain, with about 127,139 defined as having mild psoriasis and an additional 3,831 with severe cases, Gelfand and his team matched each person with psoriasis to as many as five control patients without the condition.
Gelfand and his colleagues found that the rate of heart attack was 5.13 per 1,000 patients with severe psoriasis, 4.03 per 1,000 for patients with mild psoriasis, and 3.58 for those without the skin condition.
Dr. Christopher Ritchlin, director of immunology research at the University of Rochester's Strong Memorial Hospital, said that the link between coronary artery disease and psoriasis was probably real and that he too was pursuing further studies.
"The view now is that psoriasis can be a systemic disease," said Ritchlin, who published a landmark study three years ago on how bones and joints are damaged by psoriatic arthritis, a condition that occurs in 10% to 15% of people with psoriasis.
Ritchlin said Gelfand and colleagues were on the right track showing how the disorder could affect the cardiovascular system because psoriasis might affect many systems "from the joints to the eyes to the GI tract, where some people get colitis."
He and his team are examining how psoriasis may also have a link to metabolic disorders, such as diabetes.