SAN DIEGO – A large study has determined that psoriasis is not an independent risk factor for ischemic heart disease, based on Framingham Risk Scores.
While previous studies have demonstrated that cardiac mortality is increased in patients with psoriasis, it is also known that people with the skin condition have a higher prevalence of smoking, alcohol consumption, obesity, diabetes, and dyslipidemia, researchers reported in a poster session at the annual meeting of the American Academy of Dermatology.
Dr. Marian T. McEvoy
"Is this increase in ischemic heart disease due to traditional risk factors, or is psoriasis an additional independent risk factor?" wrote the investigators, who were led by Dr. Marian T. McEvoy, in the abstract.
They performed a population-based analysis of 1,338 adults with psoriasis who resided in Olmstead County, Minn., between 1998 and 2008 to evaluate the validity of the Framingham Risk Score (FRS) in predicting the incidence of ischemic heart disease in the study cohort. The FRS is a validated measure of standard ischemic heart disease risk factors.
Dr. McEvoy, a dermatologist at the Mayo Clinic in Rochester, Minn., and her associates compared the risk of cardiac death and myocardial infarction based on the FRS with the actual incidence of myocardial infarction and cardiac death in the study population, which was limited to patients older than age 30 but younger than age 80. They used Poisson regression models and standardized incidence ratios for statistical analysis.
The researchers reported that full Framingham risk factors were available for 974 of the 1,338 patients (73%). They predicted that the median 10-year risk of cardiac events based on the FRS was 3.8%, while the observed 10-year risk of cardiac events was 5.5%. However, there were 44 observed cardiac events compared with 47.7 FRS-predicted cardiac events, which translated into a standardized incidence ratio between the two groups of 0.9. Standardized incidence ratios also showed no statistically significant differences between the two groups when analyzed by gender, by age greater than 65 years, by age less than 65 years, and by whether patients were receiving systemic treatment or not.
"If psoriasis was an independent risk factor for ischemic heart disease, the observed incidence of cardiac events would have been in excess of predicted," the researchers wrote in their poster. "Since there was no statistical difference between actual and predicted events, psoriasis is not an independent risk factor for ischemic heart disease."
In a later interview, Dr. McEvoy acknowledged certain limitations of the study, including the fact that the small number of observed cardiac events (44) limited the statistical power of the study. "Since this is a retrospective study, we did not have a good tool to assess severity of psoriasis," she said. "We used surrogates based on therapy to identify those with ‘more severe disease.’ The Framingham Risk Score was valid for this group also."
The study was partially funded by a grant from Pfizer, and was made possible by a grant from Amgen/Wyeth and by the Rochester Epidemiology Project.