It’s sobering—your doctor tells you that you have an elevated chance of having a heart attack or stroke over the next 10 years. So he recommends that you start taking a statin drug right away—and stay on it for the rest of your life.

But what if your doctor is wrong? What if your cardiovascular risk actually is much lower? The online risk calculator that is being used by the medical community to figure out who needs statins, it turns out, is seriously flawed.

Nearly half the time, a patient’s actual risk is so much lower that he/she doesn’t even qualify for statins, according to new research.

The good news is that there is a simple, standard, relatively inexpensive test that your primary care doctor can order that can dramatically improve the accuracy of cardiovascular risk assessment—so that you can make the best decision.

THE STATIN NET IS TOO WIDE

In 2013, new guidelines by the American College of Cardiology and the American Heart Association swept an estimated 13 million more Americans into the “you’re a good candidate for statins” group. In all, about 45 million Americans now are candidates for statins.

But Americans need to be more cautious before they blindly agree to start taking statins, which can come with some serious side effects. These include muscle and joint pain (the most common complaint, which is sometimes severe and can include nighttime leg cramps), digestive problems such as nausea, diarrhea or constipation, memory loss, rhabdomyolysis (a rare but severe form of muscle injury that can cause kidney failure) and a slightly increased risk of developing diabetes.

Statins offer the most benefit to people with existing cardiovascular disease, and those who have high LDL (“bad”) cholesterol in combination with other risk factors, such as a genetic predisposition toward heart disease. If you don’t already have cardiovascular disease, taking statins won’t reduce your chances of dying, studies show.

The 2013 guidelines were designed to identify people who are at such high risk of having a heart attack or stroke that they would benefit from statins.

The primary tool—an online risk calculator. You or your doctor enters information about age, gender, total and HDL cholesterol, systolic blood pressure (top number) and smoking status into the web-based tool to estimate your chance of having a heart attack or stroke within 10 years. Here’s what you’re supposed to do…

  • If your 10-year risk is 5% to 7.5%, you should “consider” taking a statin.
  • If your 10-year risk is higher than 7.5%, statins are “recommended.”

Danger: The calculator widely overestimates risks, according to a recent study in Journal of the American College of Cardiology.

TO THE RESCUE: CALCIUM SCANS

Lead study author Khurram Nasir, MD, MPH, a cardiologist at Baptist Health South Florida in Miami, and his team studied 4,758 men and women ages 50 to 68 who were already enrolled in a long-term heart study and were followed for 10 years. Applying the 2013 guidelines, the researchers calculated that two-thirds of the participants were either recommended or considered for moderate-to-high-intensity statins.

But the researchers shed light on a better way to determine risk in these people. Each had undergone a coronary artery calcium scan, a computed tomography (CT) scan that can detect calcium deposits in arterial plaque, a primary driver of heart disease. A high calcium score (CAC) can predict heart disease well before symptoms arise. A low score means your risk is likely low as well. The findings…

  • Of those patients “recommended” for statins, 41% had calcium scores of zero, meaning that they showed no buildup of plaque in their coronary arteries. The zero-calcium score lowered their 10-year risk for these patients to 4.9%.
  • Of those “considered” for statins because their 10-year heart attack risk fell between a 5% and 7.5% threshold, 57% had coronary calcium scores of zero. That lowered their 10-year risk to 1.5%.

“When you combine these two groups, about 45% have a calcium score of zero, and their average 10-year risk is 4.5%, which is much below the threshold where the guidelines suggest you should be on statins,” said Dr. Nasir.

SHOULD YOU GET A CALCIUM SCAN?

A calcium scan is a good option to discuss with your physician if your 10-year cardiovascular risk is in the broad middle range of risk score between 5% and 20%. For people in this group, a low calcium number can tip the balance in helping you to decide whether to embark on a lifetime of statin pills or focus on a nondrug approach.

If your risk score is lower than 5%, it’s likely you’d have a calcium score of zero, and you’re not even a candidate for statins…and if it’s higher than 20%, it’s unlikely that the scan results would change your doctor’s recommendation to take a statin.

Like all tests, a calcium scan has risks. It delivers less radiation than many CT scans but more than a digital mammogram. The test is highly accurate in predicting risk for coronary artery disease, the most common form of heart disease, but if your score is high, you may need additional tests to confirm the finding.

While the test is noninvasive and widely available, at an average cost of about $100 to $400, it’s not usually covered by insurance.

Dr. Nasir encourages patients to feel empowered to ask for the calcium scan test to help them decide whether to take this medication—and then decide what’s right for themselves. “If you have a much lower risk than anticipated,” said Dr. Nasir, “you have the option of forgoing a lifelong commitment to pills and just focusing on lifestyle—exercising, sleeping and eating well, maintaining your weight and not smoking.”

To learn more, see Bottom Line’s The Ugly Truth About Statins and The Big Statin Question.