Still, according to Dr. Gelfand, psoriasis does seem to be an independent risk factor for heart disease. Using a Cox proportional hazard model, he found that mild psoriasis itself carries a hazard ratio of 1.54 and severe psoriasis confers an alarming hazard ratio of 7.04. By way of comparison, hyperlipidemia carries a hazard ratio of 3.08 for the patients with mild psoriasis, and 3.18 for the patients with severe psoriasis. Hypertension carries a hazard ratio of 1.11 for patients with mild psoriasis and 1.12 for those with severe disease.
Dr. Gelfand underscored a noteworthy inverse age trend in the associated risk of MI. Patients with severe psoriasis in their 20s had a hazard ratio of 4 for myocardial infarction. The risk showed a steady downward trend with age; for those in their 60s, severe psoriasis had a hazard ratio of around 1.5. Mild psoriasis showed the same hazard ratio curve, though the amplitude was lower across the age spectrum.
In a separate poster presentation, Dr. Andrea Neimann, a member of Dr. Gelfand's research team, calculated the odds ratios for various cardiovascular risk factors in the psoriatic population in the GPRD.
Patients with mild psoriasis were 27% more likely than were controls to have diabetes, 16% more likely to have hypertension, 28% more likely to have dyslipidemia, 40% more likely to be smokers, and 29% more likely to have a BMI greater than 30. Those with severe psoriasis were 86% more likely than controls to have diabetes, 25% more likely to have hypertension, 31% more likely to be dyslipidemic, 31% more likely to be smokers, and 84% more likely to be obese.
“Diabetes, smoking, and BMI are independently associated with mild and severe psoriasis, and the association between diabetes and BMI is stronger in patients with severe psoriasis than with mild psoriasis,” Dr. Neimann reported.
Studies are needed to determine the extent to which the increased heart disease burden is attributable to the psoriasis disease process itself, or whether it can be fully explained by secondary risk factors such as smoking, overeating, depression, and other psychosocial factors.
According to Dr. Gelfand, there's certainly a plausible reason to believe the skin disease itself is playing a major role. “Psoriasis is a Th-1 mediated inflammatory disease, and increasing evidence has linked chronic Th-1 inflammation with atherosclerosis and MI.”