Psoriasis: A Risk Factor for MI?
Abstract & Commentary
By Eileen C. West, MD, Director of Primary Care Women's Health, Clinical Assistant Professor of Internal Medicine; University of Oklahoma School of Medicine, Oklahoma City. Dr. West reports no financial relationship to this field of study.
Synopsis: Psoriasis sufferers may face an increased risk of having a heart attack, a new study suggests. The risk appears to be most pronounced among younger patients with more severe forms of the disease.
Source: Gelfand JM, et al. Risk of myocardial infarction in patients with psoriasis. JAMA. 2006;296:1735-1741.
Psoriasis is a disease of the immune system that can first strike at any age, causing dry, painful skin lesions that can crack, bleed and itch. Many people with psoriasis also have psoriatic arthritis, a chronic, progressive and possibly debilitating inflammatory disease that causes joint pain, stiffness and swelling, and can damage bones. Recent studies have suggested that psoriasis patients are at increased risk of developing lymphoma, and have higher rates of depression and obesity. According to the NIH, there are as many as 7.5 million Americans with psoriasis. As yet, there is no cure.
Advocates of psoriasis research are raising a hue and cry regarding a potential relationship between psoriasis and cardiovascular disease. Psoriasis is the most common T-helper cell type 1 (TH1) immunological disease. Evidence has linked TH1 diseases to cardiovascular disease. Rheumatoid arthritis (RA) is perhaps the best studied, with clear data suggesting an association between RA and coronary artery disease, which rises with more severe disease, even after factoring out known cardiovascular risk factors. So far the link between myocardial infarction and psoriasis has only been studied in the hospital setting where major cardiovascular risk factors were not taken into account. Gelfand's recent study is a prospective, population-based cohort study including patients in the United Kingdom between the ages of 20 and 90, and compares outcomes among patients with and without a diagnosis of psoriasis. More than 680,000 patients were followed. The main outcome measure was incident myocardial infarction.
The study identified patients with psoriasis which was classified as mild (n = 127,139) or severe (n = 3837) based on extent of skin involvement and/or joint symptoms requiring the use of systemic medication. For each patient with psoriasis, up to five age-matched controls without psoriasis were identified from the same office on the same start date. Data were collected by general practitioners and stored in the General Practice Research Database between 1987 and 2002. Mean follow-up time was 5.4 years. In the statistical analysis, adjustments were made for hypertension, diabetes, history of myocardial infarction, hyperlipidemia, age, sex, smoking, and body mass index.
The study found that for patients with severe psoriasis younger than age 50, psoriasis was associated with increased risk of heart attack comparable to the increased risk seen from major cardiac risk factors. The study also found a higher incidence of heart attacks in others with psoriasis as compared to a control group without psoriasis, even after accounting for obvious risk factors including smoking and hypertension.
The results add to the growing evidence linking TH1 diseases to atherosclerosis and coronary artery disease. Other TH1 diseases such as RA have been shown to be an independent risk factor for acute MI and multivessel coronary artery disease, even after adjusting for coronary risk factors. The exact mechanism by which TH1-mediated diseases predispose a patient to cardiovascular disease is unclear, but may be due to common immunological pathways. There does seem to be an association between severity of disease as measured by inflammatory markers and higher risk.
How significant is the impact of the news from this study? Although relative risk is statistically significant, attributable risk remains somewhat low. A person in their 40s with severe psoriasis has an increased risk of 1 MI in 623 patients per year. For mild psoriasis (80%) the risk is 1 MI per 3646 patients per year. And for a person in their 50's, the risks are 1 MI per 2147 patients per year with mild psoriasis and 1 MI per 430 patients per year with severe psoriasis. More data are needed, starting with a clearer understanding of clinical markers of psoriasis activity, such as body surface area and C-reactive protein levels. In the meantime, patients with psoriasis should be screened and treated for other cardiovascular risk factors such as diabetes, hyperlipidemia and hypertension, and encouraged to adopt healthy lifestyles which include maintaining a healthy body weight, quitting smoking, following a heart-healthy diet and consistent exercise.