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Early clinical trials are not always reliable, Mayo researchers say



If the data supporting new medical treatment looks too good to be true, it could be easy.

Mayo Clinic researchers have recently reviewed more than 900 randomized controlled trials that have been published in leading medical journals over the past decade and found that a surprising number of the earliest studies on treatments for chronic conditions presented exaggerated results.

"This phenomenon is referred to as the" Proteus effect. "Dr. Alex Krist, a Virginia doctor and vice chairman of the US Prevention Services Task Force, wrote in an editorial about the Mayo study of the trials the knowledge of answering a question involves a wealth of evidence and not a final exam. Early studies should be viewed with caution. "

The findings could affect doctors' discussions, new treatments, product approvals, and insurance decisions." The Food and Drug Administration, which frequently approves products based on early studies, reviews the paper's findings.

Researching the Proteus effect, researchers at Mayo's Center for the Science of Health Care examined 70 different meta-analyzes of 930 individual clinical trials.The studies looked at drug and medical device treatments for common chronic conditions that affect health expenditures in aging populations such as Driving Diabetes, Stroke, Chronic Obstructive Pulmonary Disease (COPD), Coronary Heart Disease, and Kidney Disease.

All meta-analyzes from previous studies have been published in popular journals such as JAMA, The Lancet, and the New England Journal of Medicine, as well as Mayo Clinic Proceedings. who published the Proteus effect paper in his March issue. The Mayo team found that in more than one-third of the meta-analyzes they examined-specifically, 37 percent-the first two studies of a particular treatment reported a much greater treatment effect than later studies.

On average, these early studies reported treatment effects that were more than 2.5 times greater than the overall outcomes for the same intervention. In the four most outrageous examples, the initial treatment effects were five to nine times greater than the overall effects documented in the meta-analyzes, according to the study's author, Mayo epidemiologist Dr. M. Hassan Murad

important to consider, since drugs and equipment often involve risks of side effects, and evaluation of each treatment requires weighing its risks and the likelihood of benefits, Murad said.

"Normally we are waiting for new innovations, new interventions or new tests, with hope, we want something to be effective," Murad said in an interview. "But unfortunately what we see in the first or second study [sometimes] does not seem to be as impressive as what we see later when the studies are repeated by other people in different environments with different patients."

One of the meta-analyzes that documented the largest Proteus effect, according to Murad, was a review of 24 previous clinical studies on whether long-term antipsychotic maintenance therapy can prevent relapses of future schizophrenic episodes.

The review published in the Lancet in June 201

2 found that 27 percent of patients who took antipsychotic relapses between seven and 12 months after their first episode, compared with 64 percent of control patients who had relapses during this time during a placebo , Although the first studies came to the same positive conclusions as the later studies, the effect was more pronounced in early work than in later studies, the Mayo study found.

The authors of the Lancet paper noticed even the "heterogeneous" results they found at the time, and said the differences were degree, not "direction of effect." For example, although antipsychotics reduced the risk of relapse in all patients, it was more robust in certain subgroups, such as people who had only one episode and those in remission.

One important difference between early clinical trials and those that come later is the study population: early studies are often performed on carefully maintained populations that are likely to have the greatest impact, and therefore produce the most positive data, during later studies tend to investigate larger and more diverse groups with confounding factors such as multiple overlapping health problems and very different ages [19659002] The Proteus effect, however, not only exaggerates positive findings. In 2008, JAMA published a meta-analysis of previous studies demonstrating that anticholinergics for COPD, such as inhaled tiotropium bromide, are associated with a significantly increased risk of death, heart attack, and stroke. Murad's team examined the JAMA meta-analysis and found that the early work of the inhaled anticholinergics reported higher risks for these serious adverse events than the later studies.

The Mayo team examined 16 different factors that could be associated with biased early research, including study duration, selective risk reporting, and funding sources. Although a single site rather than multiple sites was the most predictive factor for the Proteus effect, in truth none of the factors, including one, was strongly correlated with the Proteus effect. "At least for the moment, the Proteus effect is unpredictable," concludes the report.

The Mayo newspaper adds to a growing body of evidence skeptical of early medical research, but Murad said he does not see it as "anti-innovation" and does not want to see the results used by insurers to refuse treatments.

"We are not saying that they should not give [doctors] the medicine until they have many studies," Murad said. "We say you give the treatment if the patient agrees, but you will be skeptical, and the patient may be a little skeptical, which is fine."

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