The best way to know if a new medical treatment truly works is with a randomized controlled trial — the “gold standard” of research studies, also known simply as a clinical trial. Volunteers are randomly assigned to receive either the new treatment or the comparison, which may be a placebo (an inactive therapy) or a treatment that’s already available.
As the nation’s top cause of death, cardiovascular disease has been at the leading edge of evidence generation, says Dr. Robert Yeh, director of the Smith Center for Outcomes Research in Cardiology at Harvard-affiliated Beth Israel Deaconess Medical Center. “We probably have more evidence for cardiovascular treatments than for any other field of medicine,” he says. Among the studies with the greatest impact were the clinical trials that heralded new therapies to treat heart attacks. These include clot-dissolving drugs in the 1980s, followed in the 1990s by artery-opening angioplasty procedures, which remain the standard of care today. Stents, the tiny mesh tubes used in these procedures, have also been extensively studied in clinical trials (see “Testing devices: Different dilemmas”).
|Testing devices: Different dilemmasDevices used to treat heart problems include stents, pacemakers, artificial heart valves, and more. While some argue that new devices should be compared against a sham (inactive) device or procedure, that raises ethical issues related to the potential risks to people receiving the sham. In some cases, devices can be pitted against drug therapy. Just like computers, however, devices are constantly being updated and improved, so by the time the trial is completed, the device may be on its third iteration. And over time, doctors also improve their skills for deploying new devices, another factor that can affect the success of the device.|
The price of success?
The use of medications after a heart attack is also based on findings from clinical trials. These include low-dose aspirin, cholesterol-lowering statins, and blood pressure drugs. Because of the strength of the evidence, physicians feel very confident about these drugs’ benefits. In fact, these treatments have cut the risk of a repeat heart attack in half.
However, future trials of new therapies to further lower that risk must include many thousands of participants to show even a modest improvement over the best available treatments. These big trials are very costly, which means that even major drug companies are moving away from developing and testing new cardiovascular medications, says Dr. Yeh.
Clues, not causes
In contrast, when it comes to the lifestyle advice doctors offer about preventing heart disease or slowing its progression, the evidence isn’t quite as definitive. Much of it comes from observational studies, which follow a large group of people over a long period of time. Through questionnaires or interviews, researchers gather information on a wide range of possible influences — diet, exercise, and medical and family history, for example.
Although findings from these studies provide clues to habits — both good and bad — that affect the heart, they can’t prove cause and effect. Researchers attempt to control for confounding variables that might affect the results (age, race, sex, and socioeconomic status, to name a few), but that’s not foolproof, Dr. Yeh says. For example, observational studies suggested that taking hormone therapy (estrogen and progestins) appeared to lower the risk of heart disease in perimenopausal and postmenopausal women. But in the late 1990s, clinical trials showed a complete reversal of that assumption: hormone therapy actually increased the risk of heart disease.
Still, clinical trials are not always practical — or even ethical. For instance, a trial of cigarette smoking is unthinkable. Diet and nutrition research is especially tricky. In observational studies, people may not remember what or how much they actually ate. And diet is influenced not just by socioeconomic factors but also education and culture, which may themselves affect heart disease risk, says Dr. Yeh.
Getting people to stick to a specific diet for years is difficult. Still, several long-term clinical trials suggest that a Mediterranean diet is more effective than a reduced-fat diet for preventing heart attacks and related problems.
Despite their limitations, observational studies are generally easier to conduct than clinical trials. Scientists can tap growing amounts of health-related data, from electronic medical records as well as wearable devices that record the heart’s rate and rhythm, for example. The availability of all these data — coupled with today’s enhanced computing power — means that doing observational research may be simpler and more efficient than in the past, says Dr. Yeh.
Bible verses for today’s meditation and inspiration: Matthew E. McLaren
“Finally, brothers and sisters, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable–if anything is excellent or praiseworthy–think about such things.” – Philippians 4:8
“Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours.” – Mark 11:24
“Anxiety weighs down the heart, but a kind word cheers it up.” – Proverbs 12:25
“Who of you by worrying can add a single hour to your life?” – Luke 12:25
“For I know the plans I have for you, declares the Lord, plans for welfare and not for evil, to give you a future and a hope.” – Jeremiah 29:11
“If you, then, though you are evil, know how to give good gifts to your children, how much more will your Father in heaven give good gifts to those who ask him!” – Matthew 7:11
“A cheerful heart is good medicine, but a crushed spirit dries up the bones.” – Proverbs 17:22
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