September 21, 2010
Widely Used But Flawed Calculator for Heart Attack Risk May Cause Improper Treatment
A new study published last month in The Journal of General Internal Medicine suggests that a commonly used web tool that calculates a person's heart attack risk misclassifies 15 percent of the people who use it. This tool improperly pushes almost four million people into a higher risk category which means that these people are more likely to be treated with medication. A disproportionate number of those placed in a higher risk category are women. An older, equally user friendly tool is far more accurate. The NY Times article explains:
The newer [flawed] calculator was devised in 2001 as a simplified, pencil-and-paper version of a complicated mathematical formula developed from evidence accumulated over decades by a well-known epidemiological survey, the Framingham Heart Study, a joint project of Boston University and the National Heart, Lung and Blood Institute.
Both formulas require the same seven pieces of information: age, sex, total cholesterol, “good” HDL cholesterol, smoking status, systolic blood pressure and whether one takes drugs for hypertension. The simplified system was developed so doctors and patients would not need a computer to calculate heart attack risk. Each risk factor corresponds to a number of points; the more points you have, the higher your risk of a heart attack.
Now that computers and hand-held electronic devices are all but universal, however, the original, more complicated formula is accessible to nearly everyone. Yet the simplified tool remains in broad use because it has been programmed into many Web sites and computer applications. And because most of these programs do not tell the user which method is being employed, it is impossible to tell the difference.
“Even if it’s just a 5 percent difference of undertreatment versus overtreatment — why use a less accurate method?” said Dr. Kevin Fiscella, a professor of family and preventive medicine at the University of Rochester. “Especially when it’s quite easy to use a more accurate method with electronic devices.” Dr. Fiscella is a co-author of an editorial in the same journal about the study. Among the sites that use the simplified tool are those of the American Heart Association, the Mayo Clinic and many drug companies.
The risk calculator on americanheart.org, the heart association’s Web site, carries the logo of the Pharmaceutical Roundtable, a drug industry group, with a note that says, “The Pharmaceutical Roundtable is a proud sponsor of this risk calculator.”
In a telephone interview, Dr. Fiscella said he suspected the drug industry of promoting the less accurate method to expand the market share of patients who are eligible for cholesterol-lowering statin drugs.