The cardiovascular “risk calculators” medical providers commonly use to assess patients’ likelihood of suffering a heart attack or stroke may greatly overestimate the danger in some patients and underestimate it in others, according to a new study published in Annals of Internal Medicine.
Both scenarios pose potential perils for patients, since clinicians often use data from risk calculators to help guide treatment decisions, such as whether a patient needs cholesterol-lowering statins and daily aspirin therapy for heart attack and stroke prevention, or just watchful waiting and follow-up exams.
Miscalculating risk could lead to healthy people incurring higher healthcare costs and needless exposure to medication side effects, or cause those who are genuinely at high risk for heart attacks and strokes to miss out on crucial treatments.
Highlighting the Need for Personalized Risk Assessment
The researchers concluded that physicians and medical guidelines put too much emphasis on standardized prediction algorithms (also known as risk scores or calculators) that only look at certain factors, such as gender, age, smoking, cholesterol levels, and blood pressure, while underrating the importance of individualized risk assessment.
“Our results reveal a lack of predictive accuracy in risk calculators and highlight an urgent need to reexamine and fine-tune our existing risk assessment techniques,” senior investigator Michael Blaha, MD, MPH, director of clinical research at the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, stated in a news release.
“The take-home message here is that as important as guidelines are, they are just a blueprint, a starting point for a conversation between patient and physician about the risks and benefits of different treatments or preventive strategies,” added Dr. Blaha.
Best and Worst Heart Attack Risk Calculators
The study included 4,227 people of diverse ethnicities, ages 50 to 74, who were initially free of clinical cardiovascular disease (CVD), the leading cause of death in the US. Participants were tracked for ten years, with their actual rate of CVD events compared to predictions from five widely used risk scoring algorithms.
Among the study’s findings are the following:
- The least accurate prediction algorithm was the 2013 American Heart Association/American College of Cardiology calculator, which overestimated men’s risk by 154 percent and women’s risk by 67 percent. In the group with a predicted 10-year heart attack risk of 7.5 to 10 percent–the threshold at which statin therapy is advised, the actual rate of heart attacks and strokes was only 3 percent in men and 5.1 percent in women, well below the level at which medication should be considered, according to national guidelines.
- The most accurate predictor was the Reynolds risk score, which overestimated men’s risk by 9 percent, but underestimated it by 21 percent in women. Along with age, gender, smoking, cholesterol, and blood pressure, the Reynolds score also includes a family history of early heart disease and levels of the inflammatory marker high-sensitivity C-reactive protein.
A Key Takeaway for Fighting the No. 1 Killer of Americans
Miscalculations of heart attack and stroke risk are particularly problematic for patients whose scores create uncertainty about whether or not they are candidates for drug therapy. The AHA advises statins for people with a 7.5 percent or higher risk for suffering a heart attack in the next ten years.
“Additional testing could be a much-needed tiebreaker in the all-too-common ‘to treat or not to treat’ dilemmas,” says study co-author Roger Blumenthal, MD, professor of medicine and director of the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease. “Such testing should be considered in all patients with marginal risk scores — those in whom the decision to treat with long-term statin and aspirin remains unclear.”
For example, a recent study of more than 95,000 patients published in Future Cardiology illustrates how additional testing may improve risk stratification. The researchers reported that based only on traditional lipid screening, about 30 percent of patients were found to be at risk. However, when the patients were evaluated with a multi-marker approach that included inflammation testing, 70 percent were found to be at risk.
Research indicates that nearly 50 percent of all heart attacks and strokes occur in people with normal cholesterol, with a substantial body of research suggesting that inflammation in the arterial wall is a substantial contributor to this “hidden risk” for cardiovascular events.