People with psoriasis have an increased risk of serious medical illness, and the more severe their skin disease, the more severe the risk for other conditions, new research finds.
Those with the most severe psoriasis - affecting more than 10 percent of the skin surface - are at nearly twice the risk of heart and blood vessel disease compared to people without psoriasis, Dr. Joel Gelfand, an associate professor of dermatology at the University of Pennsylvania Perelman School of Medicine in Philadelphia, and his colleagues report.
The researchers also found an increased risk of chronic lung disease, diabetes, kidney disease, joint problems and other health conditions among psoriasis patients.
"People with psoriasis are prone to other major health and medical problems that need to be thought about holistically in caring for their disease," Gelfand said. "We can now for the first time explain how the degree of body surface area involved predicts the risk of other health problems, which can help them make informed decisions."
Red, scaly plaques and patches on the skin are typical of psoriasis, which is caused by the immune system sending erroneous signals that tell skin cells to multiply too quickly.
About 7.5 million people in the U.S. have psoriasis, according to the American Academy of Dermatology.
While several studies have linked psoriasis to heart disease, stroke, diabetes, and other health problems, Gelfand and his team note in JAMA Dermatology, it has not been clear whether psoriasis severity is related to the degree of risk for those other conditions.
Most investigations have used the type of psoriasis therapy as a marker for disease severity, they add, which may be inaccurate because not all patients with severe disease receive appropriate therapy, and the therapy itself could affect disease risk.
The researchers looked at electronic medical records from the UK for 9,035 psoriasis patients whose illness severity had been determined by how much of their skin surface area was affected by psoriasis.
Just over half had mild disease, meaning it affected less than 3 percent of their skin; 36 percent had moderate disease (up to 10 percent of skin area) and 12 percent had severe disease (more than 10 percent of skin affected).
The researchers then matched each patient to 10 similar people in the database without psoriasis for comparison.
Overall, the risk for any other type of serious illness was 11 percent higher for people with mild psoriasis than for their counterparts in the comparison group, 15 percent higher for patients with moderate psoriasis and 35 percent higher for those with severe psoriasis.
Patients with moderate psoriasis were 22 percent more likely to have diabetes than people without the skin condition, for example, while those with severe psoriasis had a 32 percent increased risk of diabetes.
Moderate psoriasis also conferred a 36 percent increased risk of diabetes with complications such as eye disease, while severe psoriasis conferred an 87 percent higher risk.
Moderate and severe psoriasis increased the risk of cardiovascular disease by 39 percent and 81 percent, respectively.
People with psoriasis are known to have more inflammation in their blood vessels, which probably accounts for some of their increased risk of other illnesses, Gelfand said.
Also, he noted, genes related to heart disease are active in the skin cells of psoriasis patients, so those cells make substances - such as the blood-pressure-boosting enzyme renin - that circulate throughout the blood.
It's not clear whether effective psoriasis treatment will reduce the risk of these illnesses, Gelfand said, but he and his colleagues are currently conducting a study to test whether patients undergoing treatment for psoriasis have less inflammation in their blood vessels.
For now, he added, the new findings show that people with psoriasis should take extra care to maintain their health. "If you have mild psoriasis, your risk of these other conditions is quite low when it comes down to it, but it's still a warning sign and a reminder that it's important to undergo preventative health examinations," Gelfand said.
People with more severe psoriasis, he added, "need to take this information very seriously."