We Don’t Know If Most Medical Treatments Work, and We Know Even Less About Whether They Cause Harm: Study


From The Conversation: “Only one in 20 medical treatments have high-quality evidence to support their benefits, according to a recent study. The study also found that harms of treatments are measured much more rarely (a third as much) as benefits.

Patients and doctors – and anyone who pays for them – need to know that medical treatments are safe and effective, but it’s an open secret in the medical field that not all treatments, including ones that are commonly used, are safe and effective. For example, antiarrhythmic drugs were widely prescribed in the belief that they would reduce heart attack deaths until a clinical trial found that they actually increased the risk of death.

. . . So how big is this problem?

In the early 2000s, researchers estimated that between quarter and a half of treatments are supported by high-quality evidence. But these estimates are now out of date and used old methods (such as researcher opinion) to determine whether the evidence was high quality or not. More recently, in 2020, a more rigorous estimate was published and found that only 10% of medical treatments were based on high-quality evidence. However, this estimate was based on a small sample of 151 studies.

Meanwhile, some continue to insist that most treatments must work. How else can we explain that we live ten years longer than our great-grandparents? Yet the extension in lifespan is explicable at least partly by public health measures such as clean water, better nutrition and restrictions on smoking.

A more accurate picture

To resolve the controversy about the proportion of treatments that are based on good evidence, an international team of researchers from the UK (University of Oxford), US, Switzerland and Greece conducted a large study of 1,567 healthcare treatments. The sample included all treatments tested in Cochrane Reviews between 2008 and 2021. Cochrane Reviews are rigorous studies that amalgamate all available relevant evidence about treatments. They are often referenced in national and international healthcare guidelines.

. . . The study revealed that 95% of treatments do not have high-quality evidence to support their benefits. Worse, the harms are reported in only about 33% of Cochrane Reviews.”

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  1. Actually we do know that the benefits of many treatments are exaggerated. Take the highly promoted statins, for instance, without pre-existing heart disease 98% of people do not benefit at all from statins. Statins do not extend lifespan. Even with preexisting heart disease, one study found that 96% saw no benefit from statins over 5 years.

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  2. I don’t think this idea of “high-quality” evidence via RCEs is really the best approach, because I don’t see how it can support good outcomes for individual patients. Since the studies focus on aggregate metrics, they don’t provide evidence of how the factors of a particular case might impact outcomes. Since the studies use a definition of “effectiveness” designed by the authors, they can result in an epistemic injustice where the goals and preferences of patients are ignored. More open exploration of effects is probably more useful.

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