The 2013 American College of Cardiology/American Heart Association (ACC/AHA) guidelines for the use of cholesterol-lowering statins in people with a risk of heart disease may be too generic. According to a new study from the Duke Clinical Research Institute (DCRI), the guidelines may exclude middle-aged adults who would benefit from the drugs and include too many older adults.

Small adjustments to guidelines could enable doctors to identify more people between the ages of 40 and 55 with premature heart disease and prevent the unnecessary medication of many adults older than age 65, according to the analysis, which was published in the March 2015 issue of the Journal of the American College of Cardiology.

“The recommendations appear to be one-size-fits-all for patients in a variety of groups,” says Duke biostatistician Michael Pencina, PhD, a senior author of the paper. “We were interested in how tailoring the guidelines might get beneficial treatment to those who really need it and avoid over-treating patients whose risk may only be their sex and age.”

The guidelines calculate a person’s risk of developing heart disease in the next 10 years based on a variety of factors including age, sex, race, cholesterol, blood pressure, prior treatment for high blood pressure, and smoking status. According to the ACC/AHA guidelines, doctors should consider treating any patient whose 10-year risk is 7.5% or higher.

After applying the new guidelines to 3,685 people who participated in a section of the Framingham Heart Study that began in 1975, researchers found that basing treatment on a 7.5% risk would have missed more than one-half of participants aged 40 to 55 who did, in fact, develop heart disease and who could have benefitted from statins, which lower cholesterol and triglycerides in the blood.

Lowering the treatment threshold for patients aged 40 to 55 to a 5% or higher risk could capture more middle-aged adults who develop heart disease early, but—even then—the guidelines are imperfect, failing to consider factors such as family history in a young person’s heart risk, says Dr. Ann Marie Navar-Boggan, a cardiology fellow at DCRI and the lead author of the paper.

On the other end of the spectrum, current guidelines would have over-recommended statins for adults older than age 60—a large portion of whom continued to be tracked in the Framingham study and hadn’t developed heart disease during the 10-year timeframe that followed the observation period.

Most men older than 65 years would fall into the treatment category just because of their age and sex. In this case, the 7.5% risk threshold may be too low, Navar-Boggan says.

“The study found that by raising that threshold to 15%, we could continue to identify the same proportion of men who will go on to have heart disease, but would reduce treatment for those who will not, eliminating unnecessary drug treatment for many patients,” she says.

The study has its limitations, the authors note, including using a population that lacked geographic and ethnic diversity. But they hope it will prompt further investigation and improvements for the next round of guidelines on the use of statins.

“This is really showing the importance of considering different thresholds for men and women. To date, the guidelines haven’t made variations in recommendations. The study shows we may potentially be able to do better by tailoring those guidelines.”

In addition to Pencina and Navar-Boggan, study authors included Eric D. Peterson, Ralph B. D’Agostino, Sr., and Allan D. Sniderman.