11 October 2010
ByAppeared in BioNews 579
Researchers in the US have shown a gene-based test designed to predict the risk of Coronary Artery Disease (CAD) is only marginally better than existing methods.
CAD occurs when fatty deposits called plaques build up in the coronary arteries supplying blood to the heart. These can eventually become blocked and prevent oxygen from reaching the heart muscle, weakening it and increasing the risk of heart attacks. This condition is linked to factors such as age and genetic makeup, as well as lifestyle factors, such as body weight, smoking and stress levels.
A physician will take these factors into account when predicting an individual's risk, but current risk prediction models are not without their problems.
Several tests are used to diagnose CAD, with coronary angiography seen as the current gold standard. However, this is an expensive and invasive test, which carries a degree of risk because the procedure involves putting a catheter into the arm/groin and examining blood vessels around the heart using dye. There is therefore a need for a non-invasive, cost-effective way of analysing the risk of developing CAD.
The developers of a new genetic test available in the US, which screens for 23 genes thought to be linked to CAD, claim that they are now able to do this.
Researchers in the US set out to assess whether this new genetic test was more effective at predicting CAD than the other methods currently in use. This involved collecting data from 39 centres around the US on 526 patients who had complained of chest pain. Patients' blood samples were analysed using the genetic test and given a risk score accordingly. They then underwent coronary angiography to determine whether the patient had the condition or not - defined as narrowing of one heart blood vessel by 50 percent or more.
Results from the genetic risk score were analysed for their effectiveness in predicting whether the individuals had CAD or not. The study showed that this test was able to predict CAD more often than patient characteristic tests, but this improvement was relatively small and many patients were incorrectly classified.
The data suggests this genetic test does not provide enough of an improvement to justify its current use, but future developments may improve its accuracy.
The study findings were published in Annals of Internal Medicine.