Doctors can also make mistakes?! Do you really understand "evidence-based medicine"?

"Evidence-based medicine" has become a hot word on the Internet in recent years. However, if you read carefully, you will find that in a considerable number of online articles involving this term, the authors do not really understand this term.

Written by | Wang Chenguang (PhD in Biology, former professor of Peking Union Medical College) , Li Changqing (PhD in Medicine, practicing physician in the United States)

On the Chinese Internet, "evidence-based medicine" is a high-sounding term. Not only do medical science popularization practitioners often mention it, but many science enthusiasts also often mention "evidence-based" to show that they have medical literacy. Many people believe that adhering to "evidence-based" can reduce the risk of being deceived and improve the health of themselves and their families.

This idea is not completely unreasonable, but there are two problems in reality: first, it is not easy for the general public to truly understand the connotation of this concept; second, based on the first point, the vast majority of the public do not have the ability to practice "evidence-based" themselves.

If we understand the deeper meaning of evidence-based medicine, we can also conclude that the general public does not need to understand the concept of evidence-based medicine. In fact, even ordinary professional doctors rarely have the opportunity to use evidence-based medicine from a practical perspective.

What is “evidence-based”?

The core word of evidence-based medicine is "Zheng", which means evidence. Therefore, the literal meaning of evidence-based medicine is medicine based on evidence, but its core is far more complicated than the literal concept. Evidence-based medicine was clearly proposed as a concept in the 1990s. Now we realize that the proposal and application of this concept has extraordinary significance for the development of clinical medicine and has important value for patient diagnosis and treatment.

Although the core of evidence-based medicine is evidence, it does not mean that the development of clinical medicine before the concept was proposed was not based on evidence. Medicine predates modern science, and medicine without the support of modern science does not mean that it does not rely on evidence. Even in the simple medicine of ancient times, there is a shadow of evidence in the diagnosis and treatment mixed with witchcraft, such as bloodletting. Evidence-based medicine was proposed as an independent concept, not to confirm the status of evidence in medical practice, but to pay more attention to the source of evidence and the quality of evidence.

Just as every progress in medicine is to address certain, unmet clinical needs, the concept of evidence-based medicine is also based on the same need, which boils down to one point, that is, to solve the uncertainty of clinical diagnosis and treatment. This is fully reflected in the definition of evidence-based medicine by mainstream medical institutions, that is, to use scientific methods to organize and review current data, establish clear standards, and improve and serve health care decisions.

For ordinary readers, the above interpretation may still make it difficult for them to understand this concept. Let us take the COVID-19 pandemic, which is gradually ending, as an example to see how evidence-based medicine is applied to the treatment of COVID-19 as the epidemic develops.

Soon after the outbreak began, researchers quickly identified the virus type, the course of disease after infection, and the characteristics of high-risk groups. Once it became clear that the elderly and patients with certain types of underlying diseases had a much higher risk of severe illness and death than other groups, the urgent clinical issue to be addressed was how to reduce the risk of severe illness and death in this group.

As a result, many pharmaceutical companies and research institutions around the world have focused their main efforts on vaccine and drug research and development. You may still remember that chloroquine, artemisinin and some antiviral drugs were first included in the screening range because these marketed drugs can be directly used in clinical trials of patients without the need to conduct time-consuming preclinical studies from scratch. After a few years of epidemics, the research field has accumulated hundreds of thousands of papers on the new crown, including tens of thousands of papers related to drugs. There are nearly 3,000 papers studying the effect of chloroquine on the new crown alone. The results of these articles are extremely confusing, and they are roughly divided into two conclusions: chloroquine is effective and ineffective in treating new crown infections. As a result, some countries and regions have included chloroquine in the treatment of new crowns.

Faced with the vast amount of evidence on chloroquine for treating COVID-19, how should we choose? This involves the second important link in the application of evidence-based medicine: evidence selection. This is easy to understand, but to truly achieve it is the most difficult and most critical link in the entire practice of evidence-based medicine.

How can we ensure that the best evidence (data) is selected and those of poor quality are discarded? In short, it is to critically examine the evidence and make a scientific assessment of the evidence. Once the evidence is determined, the next step is to establish standards (such as clinical guidelines) and re-evaluate the clinical application effect in the later stage.

Following the above process, mainstream medical and health care institutions including the World Health Organization concluded that chloroquine is ineffective in treating COVID-19 infection. It is also following the same process that Pfizer's Paxlovid drug stood out, effectively reducing the conversion of infected people to severe cases and saving many lives.

Four stages of the development of evidence-based medicine

To further understand evidence-based medicine, we need to review the development history of this concept, which can be roughly divided into the embryonic stage, the evidence (or data) medicine stage, the concept birth stage and the application stage.

The embryonic stage was around the middle of the last century (1950s-1960s), and the representative figure of this period was Archie Cochrane. The medical community is familiar with Dr. Cochrane, and the Cochrane Collaboration is named after him. This is an independent non-profit, non-governmental organization, with more than 37,000 volunteers from more than 170 countries and regions around the world. The purpose of the organization is to organize medical research information in a systematic way, and to provide valuable information to medical professionals, patients, medical policy makers, etc. in accordance with the principles of evidence-based medicine, so as to facilitate medical choices. This shows Dr. Cochrane's status and important contribution in the history of the development of evidence-based medicine, and he is therefore recognized as the founder of evidence-based medicine.

In 1972, Dr. Cochrane published the book Effectiveness and Efficiency: Random Reflections on Health Services, which systematically expounded the importance of randomized controlled design in clinical trials. Since then, randomized controlled design has become the soul of clinical medical research, and its influence has also extended to the field of basic biomedical research.

With the widespread application of randomized controlled trials in medical research, analytical methods in related disciplines such as medical statistics have also been developed. Evidence-based medicine has entered the second period: evidence (or data) medicine. Since the 1980s, medicine has combined with other disciplines to create systematic analytical methods for medical research. In this stage, researchers began to pay attention to and integrate the results and conclusions of different studies.

After decades of accumulation, the concept of evidence-based medicine has gradually taken shape and has been widely recognized in the 1990s, which is the birth period of the concept. David Sackett and Gordon Guyatt are the representatives of this stage, and they are in a master-apprentice relationship. Sackett is the founder of the Canadian Center for Evidence-Based Medicine. He played a key role in the formulation of evidence-based medicine guidelines and frameworks, promoted the development of evidence-based medicine, and some people call him the "father of evidence-based medicine." His student Guyatt actively advocated evidence-based medicine while working at McMaster University Hospital in Canada. On this basis, he proposed the concept of "clinical guidelines" and conducted extensive research in this field. He also published books such as "User's Guide to Evidence-Based Medicine" to help doctors and researchers better apply the latest research data.

Since the beginning of this century, the principles of evidence-based medicine have gradually penetrated into all aspects of clinical practice, truly realizing the transformation of concepts into clinical applications. Medical management agencies regularly organize experts in the field to develop guidelines for certain medical issues. Medical professionals such as doctors and nurses also use these clinical guidelines more widely to provide services to patients with diagnosis and treatment plans based on the best evidence.

No matter how good the medical plan is, it will eventually be used on the patient. Based on ethical principles, doctors need to fully communicate diagnosis and treatment information with patients, but the treatment plan cannot override the patient's personal choice, even if there is strong evidence to support the treatment plan. For example, a newly launched cancer drug can extend the life expectancy of advanced patients, but it also has potential side effects and is expensive. At this time, the patient is faced with not only the question of whether the use of this drug can prolong life, but also the impact of side effects on quality of life, as well as factors such as the financial burden on the family. After the doctor introduces various treatment options to the patient in detail, the choice is on the patient's side.

The distance between ordinary people and “evidence-based”

In summary, the development of evidence-based medicine is closely related to basic research in life sciences, advances in medical technology, and the medical community's constant pursuit of optimal clinical practice. Its core concept is to give priority to scientific evidence in medical decision-making to provide more effective, safe, and personalized medical care. This approach has played a key role in improving the quality of healthcare and patient outcomes.

Some science enthusiasts, even popular science writers and doctors, who always talk about evidence-based medicine, do not actually understand what evidence-based medicine is (this is easy to see from their remarks. The author has communicated with some of them and confirmed this judgment). The two most common misunderstandings are:

The first is to regard "evidence-based medicine" as another name for "modern medicine." Evidence-based medicine is actually the product of modern medicine (medical science) at a certain stage of development. It has a dependent relationship with modern medicine and has become an important part of modern medicine.

Another misunderstanding is to regard large-sample randomized double-blind trials as evidence-based medicine. In fact, the results of blind trials are only one type of evidence (data) used to evaluate evidence-based medicine.

Evidence-based medicine has become fashionable on the Internet. One of the reasons is that many people are worried that domestic medical personnel and even medical institutions do not understand or talk about evidence-based medicine, so they need to learn more knowledge to protect themselves.

The same mentality is not only reflected in the public's understanding of medical treatment, but also exists in every aspect of life. We can compare various dairy products to medicines and treatment methods provided by medical institutions. Everyone hopes to buy dairy products with guaranteed quality and safety, but how do we know that the dairy products we buy are indeed of the quality they should be? How to ensure that they do not contain melamine? Are the ingredients in dairy products that are beneficial to health up to standard? As ordinary consumers, we only need to look at and can only look at the ingredients marked on the milk packaging in the supermarket. Even if some dairy products contain melamine (of course it will not be marked), reading the label information is still the only way for consumers to understand the ingredients of the product. Although these ingredients can be discovered through testing, as ordinary consumers, it is impossible to test the quality of daily necessities.

The quality of dairy products on the market involves production, storage, transportation and sales, all of which involve joint supervision by relevant government departments. Market supervision departments will also conduct regular inspections of dairy products on the market to ensure that the products meet standards and regulations. In addition, packaged dairy products need to submit product ingredient inspection data before they are put on the market, register the product and obtain marketing authorization. Finally, product information is reflected on the label, including ingredients, production and expiration dates.

A dairy product of qualified quality is the result of the joint operation of the above-mentioned departments and institutions - and as an ordinary consumer, there is very little you can do in the whole process.

Similarly, the popularization of evidence-based medicine requires the coordination of the entire society, and cannot rely on ordinary people's spare-time learning. In a society that respects medical science, ordinary people do not need to consider whether the diagnosis and treatment they receive complies with the evidence-based procedure, just like they do not need to get all the test reports of the product when buying dairy products. Not to mention that they always mention evidence-based medicine, and even doctors do not need to mention evidence-based medicine all the time and show it to others like a medal.

Conversely, if the entire medical system does not respect the spirit of evidence-based medicine (which is actually the scientific spirit), then the practice of evidence-based medicine in the entire society cannot be implemented. Even if a patient or a patient's family member is aware of evidence-based medicine, if they encounter a complex disease that requires medical intervention, such as cancer, they can only cooperate with doctors and medical institutions. For some diagnostic and treatment methods that do not comply with the guidelines, they can only endure them in many cases - and most people do not have the ability to identify which measures do not comply with medical guidelines.

In such a system, even if an entire hospital follows the ethos of evidence-based medicine, it is useless because the medical insurance institutions, the experts who formulate medical insurance policies, and even the experts who formulate medical guidelines may not follow evidence-based medicine. In this case, the treatment plans, drug choices, and all other medical measures you receive are unlikely to follow evidence-based medicine.

The development of medicine is a gradual process. We have learned a lot, but there are still many unknown areas. In the concept of "evidence-based medicine", "follow" reflects a dynamic process and is a real-time tracking of medical progress. From this point of view, evidence-based medicine is not a matter for ordinary people, or even for medical staff. Evidence-based medicine involves complex medical knowledge and medical practice. The public who lack relevant education and training will not only not benefit from sticking to medical guidelines and literature, but may also be harmed by misinterpretation. As ordinary people, what we should really focus on is the scientific spirit, or the evidence-based spirit, rather than evidence-based practice.

This article is supported by the Science Popularization China Starry Sky Project

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

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