June 27, 2024 – If you’re taking a statin drug to prevent heart disease, it’s possible that, sometime in the next year or two, your doctor might tell you that it’s no longer necessary.
If and when that change happens, it will reflect the use of a new risk calculator the American Heart Association released last year. Using this calculator, along with data from a national nutrition and health survey, a new study estimates that adults ages 40-75 have half the risk of getting atherosclerotic heart disease within 10 years, compared to what was earlier projected.
More than 45 million Americans are considered eligible to take statin drugs to prevent heart disease, which can lead to heart attacks or strokes. These guidelines are based on a 2013 risk calculator known as the pooled cohort equations. In 2023, the American Heart Association released an updated calculator, the Predicting Risk of Cardiovascular Disease Events (PREVENT) equations.
The researchers in the new study compared the 10-year predicted risk using both calculators for 3,785 adults who took part in the CDC’s National Health and Nutrition Examination Survey from 2017 to March 2020. The people in the the study were all eligible for statins, but only 20% of them were actually taking the drugs.
After weighting the survey data to be nationally representative, the study authors found that use of the 2023 calculator reduced the average 10-year risk of heart disease among adults from 8% to 4.3%. Across all age, sex, and racial subgroups, the average 10-year risk was lower using these guidelines.
As a result, the number of adults meeting the criteria for statin use dropped from 45.4 million to 28.3 million. So, based on these equations, 17.3 million adults for whom statins are now recommended would no longer be considered eligible. That includes 4.1 million adults who are currently taking statins.
Update Based on New Data, New Factors
Why is there such a big difference between the results of the two calculators?
One reason is that the data for the 2013 version comes from the 1960s through the 1990s, said Sadiya Khan, MD, a professor of cardiovascular epidemiology and associate professor of medicine at Northwestern University Feinberg School of Medicine in Chicago.
“Things have changed quite a bit since that time,” including the use of statins and other primary preventive measures, said Khan, who was involved in constructing either risk calculator. The larger and more recent database on which the 2023 equations are based came mostly from a warehouse of electronic health record data, according to the new study.
Also, the two calculators use different factors in estimating heart disease risk. For example, race is included in the 2013 version, but not the 2023 calculator, since it’s now recognized that there are no biological differences between races. But the baseline and the decline in estimated risk were larger for Black people (from 10.9% to 5.1%) than for the overall study sample.
“Black patients have a higher risk for cardiovascular disease, particularly stroke,” Khan said. “The most common reason is higher rates of hypertension and diabetes. It’s a combination of many social factors that add up and is considered unlikely to be biological, but it is a longstanding and hard-to-resolve problem.”
The 2023 equations include degree of kidney function and statin use that weren’t factored into the earlier calculator. The newer version also includes data on blood sugar, kidney health, and the “social deprivation index,” which is based on ZIP codes.
The study omitted ZIP codes, which were absent from the nutritional survey data, and LDL cholesterol values, which were only available for some of the people in the survey.
Despite these drawbacks, Khan, who was not involved in the study, said its main conclusions on 10-year heart disease risk are in line with other studies.
Study co-author Jeremy Sussman, MD, an associate professor at the University of Michigan, said he doubted that the omission of LDL cholesterol data could have affected the accuracy of the results significantly. “It certainly doesn’t reduce it enough to change the basic story,” he said.
When Will the Guidelines Change?
Sussman believes the study results warrant a review of the guidelines for heart disease prevention. “I think the change is substantial enough that the people who make these guidelines should at least think about what they should say about the situation.”
The paper’s lead author, Timothy S. Anderson, MD, an assistant professor at the University of Pittsburgh, went further in an interview for a news story in The Journal of the American Medical Association. Not only did he favor updating the guidelines, but he gave a timeline for when he thinks that will happen. The American Heart Association and the American College of Cardiology are scheduled to release new high blood pressure and cholesterol guidelines later this year and in 2025, respectively, he said, and he expects new guidelines for primary prevention of cardiovascular disease (or disease in the heart or blood vessels) to follow those changes.
But, in response to a question, Heart Association spokesperson Maggie Francis would say only that “the study [on 10-year heart disease risk] will be part of the body of evidence considered whenever it’s time to review clinical practice guidelines.”
Casting a Wider Net
When the new guidelines are written, Khan said, they should include risk predictions for heart failure, as mortality rates from that condition are on the rise. She also said it’s important to estimate the 30-year risk of cardiovascular heart disease, which accounts for more deaths than any other disease. Two-thirds of people without a significant 10-year risk for cardiovascular disease have a high 30-year risk, she said.
Khan said she could not estimate how many patients who are now taking statins may be advised to stop if the primary prevention guidelines change.
“When we think about thresholds for treatment, we consider at which risk level the benefits outweigh the harms,” she said. “And where are the trials that can show us that? There are studies that show that at lower risk levels – say, 5% – the benefits [of statins] outweigh the harms.”
When there is uncertainty, a doctor may order tests. Sussman, who estimates that millions of people now get these tests, said that the lower risk level the study found may lead to fewer patients getting these tests. But whether the screenings are done or not, Khan said, the ultimate decision to go on statins is between the doctor and the patient, based on a number of things, including family history.
Undertreatment Is Widespread
The most important point, Khan said, is that a minority of people who could benefit from statins are taking them, and the same goes for other kinds of preventive care.
“No matter what the guidelines evolve to, we are undertreating people, and that has to be addressed. If you look at blood pressure treatment or cholesterol treatment, or if you consider the fact that we have an epidemic of obesity and diabetes, we are undertreating people,” she said.
Khan said that by “we,” she meant not only doctors, but society as a whole. “On balance, we know that fewer people are being treated than would be economically and efficiently better," and that some of this has to do with unequal access to care.
“While statins and anti-hypertensives are incredibly cheap, they could be free,” she said. “We as a society could suggest that these medications – because of their outsized benefit for prevention, and because [cardiovascular disease] is the leading cause of death in this country – should be free.”
