FRIDAY, March 15, 2019 (HealthDay News) -- Precious few treatment guidelines for heart patients are supported by the best scientific evidence, a new study shows.
Less than one in 10 recommendations are based on results from multiple randomized controlled trials (considered the "gold standard"), and that percentage has actually dropped in the past decade, the researchers reported.
For the study, the investigators analyzed the evidence behind more than 6,300 treatment recommendations for managing heart-related conditions -- such as high blood pressure and high cholesterol -- from the American College of Cardiology and the American Heart Association (ACC/AHA).
The recommendations are categorized by the amount of evidence supporting them. Level A means evidence came from multiple randomized controlled trials. Level B means that evidence came from a single randomized controlled trial or observational studies. And level C means the recommendation is based only on expert opinion.
Only 8.5 percent of ACC/AHA recommendations relied on level A evidence, while 50 percent had level B data and 41.5 percent had level C data, the researchers found.
"In 2009, there was a call for improvement in the clinical research enterprise after [an] earlier study highlighted several deficiencies," explained senior study author Dr. Renato Lopes, a cardiologist and professor of medicine at Duke University.
"But really, despite some initiatives and a greater focus on conducting randomized controlled trials, the chasm between evidence and the need for evidence has not improved," Lopes said in a Duke news release.
"As a matter of fact, the proportion of U.S. recommendations from cardiovascular guidelines supported by high-quality evidence actually decreased from 11 percent to 9 percent in the last decade," Lopes noted.
The findings were published online March 15 in the Journal of the American Medical Association.
According to study lead author Dr. Alexander Fanaroff, "Patients should have an expectation that the science behind the care they receive is solid and will result in improved outcomes. Progress in reducing cardiovascular mortality has decelerated over the past several years, so improving the evidence base for treatment guidelines could help forestall this trend."