Only 1 in 10 Medical Treatments Is Backed by High-Quality Evidence, Study Finds

https://www.sciencealert.com/around-90-percent-of-your-medical-treatments-isn-t-backed-by-high-quality-evidence

When you visit your doctor, you might assume that the treatment they prescribe has solid evidence to back it up. But you’d be wrong. Only one in ten medical treatments are supported by high-quality evidence, our latest research shows.

The analysis, which is published in the Journal of Clinical Epidemiology, included 154 Cochrane systematic reviews published between 2015 and 2019. Only 15 (9.9 percent) had high-quality evidence according to the gold-standard method for determining whether they provide high or low-quality evidence, called GRADE (grading of recommendations, assessment, development and evaluation).

Among these, only two had statistically significant results – meaning that the results were unlikely to have arisen due to random error – and were believed by the review authors to be useful in clinical practice.

Using the same system, 37 percent had moderate, 31 percent had low, and 22 percent had very low-quality evidence.

The GRADE system looks at things like risk of bias. For example, studies that are “blinded” – in which patients don’t know whether they are getting the actual treatment or a placebo – offer higher-quality evidence than “unblinded” studies.

Blinding is important because people who know what treatment they are getting can experience greater placebo effects than those who do not know what treatment they are getting.

Among other things, GRADE also considers whether the studies were imprecise because of differences in the way the treatment was used.

In the 2016 review, researchers found that 13.5 percent – about one in seven – reported that treatments were supported by high-quality evidence. Lack of high-quality evidence, according to GRADE, means that future studies might overturn the results.

The 154 studies were chosen because they were updates of a previous review of 608 systematic reviews, conducted in 2016. This allows us to check whether reviews that had been updated with new evidence had higher-quality evidence.

They didn’t. In the 2016 study, 13.5 percent reported that treatments were supported by high-quality evidence, so there was a trend towards lower quality as more evidence was gathered.

There were a few limitations to the study. First, the sample size in the study may not have been representative, and other studies have found that over 40 percent of medical treatments are likely to be effective.

Also, the sample in the study was not large enough to check whether there were certain types of medical treatments (pharmacological, surgical, psychological) that were better than others. It is also possible that the “gold standard” for ranking evidence (GRADE) is too strict.

Too many low-quality studies

Many poor-quality trials are being published, and our study merely reflected this. Because of the pressure to “publish or perish” to survive in academia, more and more studies are being done.

In PubMed alone – a database of published medical papers – more than 12,000 new clinical trials are published every year. That’s 30 trials published every day.

Systematic reviews were designed to synthesise these, but now there are too many of those, too: over 2,000 per year published in PubMed alone.

The evidence-based medicine movement has been banging a drum about the need to improve the quality of research for more than 30 years, but, [ … ]

The post Only 1 in 10 Medical Treatments Is Backed by High-Quality Evidence, Study Finds appeared first on NewsCetera.

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