double blind method. Randomization and double blind control

Richard Dawkins is a biologist, Professor at Oxford and Berkeley, Fellow of the Royal Society of London for the Advancement of Natural Knowledge about what is useful to know about life if you use the most ordinary scientific procedure.

“Not all ideas that scientists use in their work are suitable for general use. First of all, we should be interested not just in research methods, but in tools that will help non-scientists better understand what science is and make more informed life decisions. Why do three-quarters of Americans believe in angels and hell, half in ghosts, and a third in astrology? Why does a quarter of Americans believe that the president of the United States was born outside the country and therefore cannot hold office? Why do two-fifths of Americans believe that the universe appeared later than man tamed the dog?

Let's not be defeatists who blame human stupidity for everything. Surely this is partly true, but let's be a little optimistic and imagine that everything is fixable: it's just a lack of critical thinking skills, an inability to separate personal opinion and prejudice from evidence. I believe that a double-blind controlled experiment is capable of instilling them - a kind of scientific double-edged sword, but in a good way. On the one hand, this is an excellent research tool: initially, not only the subjects, but also those people who directly conduct the experiment do not have full knowledge about the nuances of the experiment, which allows minimizing the subjective factor, in addition, there is a control group that helps to check objectivity of the obtained results. On the other hand, it is also an excellent educational, didactic tool with which you can teach people critical thinking. My idea is that you don't actually need to do double-blind controlled experiments to achieve this. One must understand the principle itself, grasp its importance and enjoy its elegance.

If every school taught children how to do double-blind controlled experiments, our thinking would improve, and in these areas:

We would understand that it is not worth making generalizations based on anecdotes - isolated cases.

We would understand how to evaluate the likelihood that an effect that seems important is actually the result of pure chance.

We would understand how difficult it is to exclude bias in mental constructions, which is far from always the result of dishonesty or corruption of any kind. This is a very important lesson. It has an extremely beneficial effect in regard to distrust of authorities and personal opinion.

We would understand that we need a habit of critical and skeptical thinking, which in the end can save the world.

blind method - the procedure for conducting a study of people's response to any impact, which consists in the fact that the subjects are not initiated into the details of the study. The method is used to exclude subjective factors that may affect the result of the experiment.

lies in the fact that not only the subjects, but also the experimenters remain ignorant of the important details of the experiment until its completion. The double-blind method eliminates the unconscious influence of the experimenter on the subject, as well as subjectivity in assessing the results of the experiment by the experimenter.

By the way! This type of control is often used in drug studies where neither the subject nor the person using the drug knows whether it is a drug or a placebo. In such a case, it is possible to separate the effects of the drug from any preconceptions about what effect should or should not have. medicine.

Term "evidence-based medicine" was proposed by a group of Canadian scientists from McMaster University (1990)

Evidence-based medicine is based on testing the effectiveness and safety of diagnostic and treatment methods in clinical trials.

Before the 90s there were no standards clinical trials. Now there are quite specific methods of evidence-based medicine, a set of rules for conducting research and subsequent analysis.

For example, what is called a “double-blind placebo-controlled method”: when neither the doctor nor the patient knows which drug the patient has got - the study drug or the placebo. However, in the CIS, these methods are still rarely used; drug trials are being conducted, but not in accordance with international standards. This, in particular, is due to the fact that large samples and the organization of clinical trials in itself is a very expensive procedure.

The vast majority of drugs that are prescribed on an outpatient basis have no proven efficacy or safety ... Among these drugs sold in pharmacies, drugs:

• Actovegin
• Cerebrolysin
• Solcoseryl
• Cortexin
• Arbidol
• Oksolin
• Essentiale
• Ademetionine
• Riboxin
• Analgin
• Prednisolone
• Polyoxidonium
• Anaferon, viferon and other interferons
• Validol
• Probiotics
• Bioparox
• Preductal
• this list includes all

The use of these "drugs" is entirely on the conscience of the attending physician, with the obligatory informed consent of the patient to use (means with unproven effectiveness). Most of this list is used nowhere else in the world, except in the CIS countries.

So, it turns out that until the 90s, people were NOT treated in accordance with the basics of evidence-based medicine (but, nevertheless, somehow cured); and now the effectiveness of most of the drugs sold in our pharmacies has not been proven, which does not prevent people from receiving a positive result in certain cases. Is it all a placebo effect? Or is it still narrow and insufficient to be guided by just one approach of evidence-based medicine?

Here's what doctors say about it:

“Still, what is modern medicine – science or art? Western medicine teaches us that this is a science, and let's sacrifice those 15-25% of patients who did not receive a positive result from treatment in such and such a study.

Why did this happen? Yes, because we still know very little about the human body and its diseases. I believe that the medicine of the future (and only then it will become a science in my understanding) will be patient-based medicine, when individual therapy will be selected for each patient. I think that in 50 years we will come to this, because the genome has already been deciphered!”

“The entire history of medicine is a history of observation and clinical experience. Standards and consensus conclusions are certainly needed, especially for young doctors, but let's not turn into smug dogmatists and recognize that tomorrow these methods will give way to even newer, yet undeveloped methods of treatment.

“No clinical trials (as well as deciphering the genome) will ever allow us to describe the whole variety of patients. Therefore, a doctor, even the most conclusive one, relies primarily on “intuition”.

It is easy to see that the problem<болей в спине>is very difficult to determine (causes of back pain can be 100). Naturally, it turned out that paracetamol was the drug of choice (because of its safety), all other methods were considered useless. Is this against common sense? After all, everyone already knows that paracetamol helps with back pain. What is the clinical significance of such recommendations - zero.

In practice, I noticed (believe me, but back pain is one of the most common complaints in America) that the use of complex therapy (but complex, no matter how creepy it sounds) helps to achieve significant results, often by trial and error. I like the combination Vioxx/Neurontin/Ultram for example. What exactly helps? Is it because all three drugs act on different mechanisms of pain suppression, or is it just a strong placebo therapy? Should I wait until this combination is put into clinical trials and give patients Tylenol, or is there still room for do-it-yourself?”

“In the conditions of Western medicine, it is often necessary to do certain studies for the purpose of “evidence” in case the patient suddenly decides to sue. Making entries in the medical history, you always try to keep in mind that all this can go to the prosecutor's table. You constantly hear about the fact that one or the other was sued.

Gradually you get used to working in such a way that, in case of emergency, you can always refer to this or that algorithm, and you will think a hundred times before experimenting or recommending something from alternative medicine.

Thus, with all its advantages, in my opinion, evidence-based medicine has significant drawbacks: it, like any statistical method, excludes an individual approach of a doctor to a patient and works only to remove a certain symptom, without taking into account the cause that caused the disease. Those. patients with the same clinical symptoms(for example, headache, high blood pressure, back pain, etc.) prescribe the same drug.

The factors that caused the symptoms should not be taken into account, the doctor's many years of experience in the treatment of such diseases, too. Those. the approach “Treat the patient, not the disease” with this statistical approach does not work at all.

In addition, a “double-blind randomized trial” is only suitable for comparing one chemical product with another, less well-known one. Such a methodology is completely unsuitable for the clinical assessment of diseases associated with a deficiency of certain substances.

And, of course, in the case of evidence-based medicine, the influence of the personality of a doctor is completely excluded, who can, with his word, both contribute to recovery, and vice versa, do not give the patient a chance, especially if the patient is easily suggestible with obvious psychosomatics.

The influence of the doctor's personality, (as well as the patient's belief in the drug and recovery) is just attributed here, which, according to some estimates, reaches 30% ii in the treatment, and this is a lot.

But, as far as alternative medicine approaches are concerned, they inherently cannot be standardized due to the individuality of this approach. But here, the patient's response rate to the drug and the duration of the disease are taken into account; Much attention is paid to prevention. However, alternative medicine does not fit into the models of insurance medicine, since often one doctor cannot control the activities of another ... How then to carry out an examination - was the patient treated correctly or not?

And another open delicate question: is it possible to adopt a branch of medicine whose mechanisms are not able to be understood - even with positive results?

The conclusion is the same - the world today is often too complicated to agree with a single judgment about a particular phenomenon. The art of a doctor, his experience and intuition in most cases mean no less than the dry statistics of evidence-based medicine.

Not all ideas that scientists use in their work are suitable for general use. We should be primarily interested not just in research methods, but in tools that will help non-scientists better understand what science is and make more informed life decisions. Why do three-quarters of Americans believe in angels and hell, half in ghosts, and a third in astrology? Why does a quarter of Americans believe that the president of the United States was born outside the country and therefore cannot hold office? Why do two-fifths of Americans believe that the universe appeared later than man tamed the dog?

Let's not be defeatists who blame human stupidity for everything. Surely this is partly true, but let's be a little optimistic and imagine that everything is fixable: it's just a lack of critical thinking skills, an inability to separate personal opinion and prejudice from evidence. I believe that a double-blind controlled experiment is capable of instilling them - a kind of scientific double-edged sword, but in a good way. On the one hand, this is an excellent research tool: initially, not only the subjects, but also those people who directly conduct the experiment do not have full knowledge about the nuances of the experiment, which allows minimizing the subjective factor, in addition, there is a control group that helps to check objectivity of the obtained results. On the other hand, it is also an excellent educational, didactic tool with which you can teach people critical thinking. My idea is that you don't actually need to do double-blind controlled experiments to achieve this. One must understand the principle itself, grasp its importance and enjoy its elegance.

If every school taught children how to do double-blind controlled experiments, our thinking would improve, and in these areas:

1. We would understand that it is not worth making generalizations based on anecdotes - isolated cases.

2. We would understand how to evaluate the likelihood that an effect that seems important is actually the result of pure chance.

3. We would understand how difficult it is to exclude bias in mental constructions, which is far from always the result of dishonesty or corruption of any kind. This is a very important lesson. It has an extremely beneficial effect in regard to distrust of authorities and personal opinion.

4. We would understand that we should not succumb to the temptations of homeopaths and other scammers and charlatans who would remain out of work.

5. We would understand that we need the habit of critical and skeptical thinking, which in the end can save the world.

What is the blind method?

blind method- the procedure for conducting a study of the reaction of people to any impact, which consists in the fact that the subjects are not initiated into the important details of the study. The method is used to exclude subjective factors that may affect the result of the experiment.

It lies in the fact that not only the subjects, but also the experimenters remain ignorant of the important details of the experiment until its completion. The double-blind method eliminates the unconscious influence of the experimenter on the subject, as well as subjectivity in assessing the results of the experiment by the experimenter.

The blind method has become widespread in medical testing. To obtain objective results, patients are divided into two groups; one group receives the new drug and the other, the control group, receives a placebo. At the same time, patients do not know which of them is in the control group. This eliminates the so-called "placebo effect", which consists in the fact that the patient's condition may improve simply because he thinks he is taking an effective medicine (on average, this occurs in 5-10% of patients). Although this method increases the objectivity of the study, it does not exclude subjective assessment the patient's condition by the doctor conducting the study. In the case of a double-blind method, the doctors directly involved in the trial also do not know which of the patients they are giving the drug and which the placebo.

The application of the method is not limited to medicine, it can and should be used in any cases where the subject or experimenter can consciously or unconsciously influence the result. For example, it is quite obvious that when peer review any project, the expert, in order to maintain objectivity, should not know who the proposal comes from. However, the organizers of the tender can also influence the result by choosing a certain expert for evaluation. specific project. Therefore, it is important that this choice is also made blindly.

Double-blindness is also used to scientifically test claims of paranormal abilities, such as the ability to read minds or determine the color of objects without the aid of sight (skin-optical perception).

In medicine, when testing the effects of new drugs - does it really work or not? - use double blind method: this is when neither those who are being treated, nor even those who are treating, are aware of what kind of medicine they are giving to a particular patient: a real one or a “dummy” (placebo). Still unclear? Let's deal with Masha and Vasya!

A steaming bowl of soup stood silently in the middle of the table and attracted all eyes.

Vasya, - Vasya's mother repeated doomedly. - There are no carrots there. Eat please.

If only Masha would be ashamed, - said mother, and Vasya and Masha were both embarrassed.

There was a long pause, during which both Vasya and Vasya's mother felt terribly sorry. Masha realized that it was time for her to intervene. No wonder he and Vasya had definitely decided to devote themselves to experimental science.

Vasya! she said decisively. - You claim that you can smell the carrot smell in this soup.

Yes, - looking at the table, Vasya answered gloomily.

And you, Aunt Marina, say that you didn’t put carrots in this soup.

Okay, - said Masha cheerfully. - We can no longer check if there were carrots in this soup, but we can check something else. Namely: can Vasya smell the boiled carrots. If it can, then there were carrots in the soup, here!

How will we do it? Vasya asked sullenly.

Very simple. Do you have carrots in the house? - Masha asked Aunt Marina.

There is, of course, - answered Vasya's mother, pointing her chin at the refrigerator. Vasya shot her an accusing glance.

Then we'll do this. Now, - Masha jumped up from the table, pulled out a bag of carrots from the refrigerator and took out one carrot from it, - we will cook this vegetable. Pour the broth into a glass, pour into another glass pure water, blindfold Vasya and let him smell both liquids and compare.

What if I'm wrong? Vasya muttered without looking into Masha's eyes.

Then eat the soup like a pretty one.

What if he's not wrong? Vasya's mother asked.

Well, then you will have to admit something, - Masha said embarrassedly.

And if Vasya guesses RANDOMLY? - Vasya's mother was indignant. - Just think, he will say at random - yes or no, but it turns out that everything is so?

Taak, - answered Masha thoughtfully. - This is problem.

And everyone thought.

O! - Vasya unexpectedly answered (by his tone, Masha immediately realized that the capricious child in him had given way to a real scientist). - I can sniff these liquids not just once, but many times. Once I may say the correct answer by accident. But if I sniff a hundred times, and every time I guess, then, mommy ... - (and the real scientist again gave way to a capricious child).

Excellent! - said Masha and began to peel the carrots.

Stop, - said Vasya's mother. - And what will we do if Vasya says every time that there are carrots. He will, of course, tell the truth every time the carrot is there. But the fact that there are no carrots there, - and mother cast a bitter look at a bowl of soup, - he will never guess.

Okay, - Masha put down the carrot and the knife and took a sheet of paper. - Let's write it down.

And she made a simple table:

Vasya, who had been looking over Masha's shoulder all this time, snatched the paper from her and redirected "Vasya is just showing off" to "Vasya is delusional".

Misguided - so misguided! Masha readily agreed. - Well, let's start the experiment, shall we? If Vasya answers correctly all the times, then ...

No, Vasya said suddenly. - Suddenly I feel carrots, but not always? Its smell is weak, you can make a mistake. If I answer correctly half the time, will it count?

Not enough yet, - his mother immediately responded. - Half the time you can answer correctly, even if you don't feel anything at all. Even if you just randomly say anything, in half the cases you will answer correctly simply according to probability theory.

Okay, - Vasya said humbly, - and what figure do you think is correct?

Well, uh, - mum thoughtfully, - for example, if you answer correctly at least ninety percent of the time ...

At sixty! Vasya retorted quickly.

At eighty! his mother replied.

At seventy! they said in unison.

Well, no, - unexpectedly said Masha, who was tired of turning her head from one to the other, like at a tennis match. - It is not right. There is no such boundary between "yes" and "no". If 50% - it means that Vasya definitely does not understand. If 100% - exactly understands. And the rest - it's so blurry. Rather yes than no, or, conversely, rather no than yes.

That's right, Mom agreed. - But Vaska and I need to agree, 70% of both of us are satisfied, right?

Yes! Vasya responded bravely. - Boil carrots already and come here, I'll sniff.

Eh no! Vasya's mother suddenly said. - Do I know you. If Masha gives you a sniff, she will prompt you.

I won't! Masha was indignant.

Mash, - Vasya's mother said softly. - I don `t want to offend you. It’s just that you will root for Vasya, and, well, I don’t know, poke a glass of water right under his nose, and take a glass of carrot broth away from his nose, well, or somehow else, I don’t know. And so Vasya will guess what is in this mug - not by smell, but by your prompts. Of course, this is not on purpose - it happens by itself, doesn't it?

Masha lowered her eyes to the table in embarrassment: it was true.

Then you, mother, offer me a mug yourself, ”Vasya said gloomily.

No, that doesn't work either, - Vasya's mother answered. - Me too interested party. I will also do the opposite. Do you know what we'll do? We use a double blind method.

Like this? Vasya and Masha were surprised together.

Well, we won't have to go blind, - my mother winked. - This expression came from medicine. The fact is that when a patient is given a medicine, he, as it were, tunes in to recovery and as a result recovers - but not because of the medicine, but because his body has mobilized. Even if a person is given a pill that does not contain any active ingredients, well, just sugar in a tablet shell, and is told that this is a miracle drug, he will feel relief. This phenomenon is called the "placebo effect". "Placebo" means "dummy" in Latin. In principle, the placebo effect is great, it kind of helps the drugs work. But if the drug is new and we are only conducting clinical trials, checking whether it is good or not, then great difficulties can arise. Here we give the patient this medicine, we see that he has become better and we conclude that the medicine is useful. What if it's not like that at all? What if the drug is actually harmful, and the patient got better because of the placebo effect? How to understand what the medicine really costs?

Well, - answered Masha, - you just have to not tell the patients that they are being treated. Sneak medicine into them, like... like carrots in soup.

In response to this remark, Vasya silently incinerated Masha with a look, and then said:

Yes, you just need to take two patients. Or not, not even two patients, but two groups of patients, that's it! And tell all patients that they are given medicine. But in fact, some are given real medicine, while others are just empty pills. And then see which group recovered better.

Great, son! Vasya's mother said. - That's how they do it in medicine. It is called blind method. The patient is as if blind, he does not know whether he is receiving medicine or a dummy. Therefore, both groups of patients will have the same placebo effect, but the drug will act only on one group. But there is a problem here too. Studies have shown that if the doctor knows that he is giving the patient real medicine, then he, as it were, transfers this knowledge to the patient. Of course, he will not tell him anything, but he will behave in such a way that the patient himself will guess that he has already got something that will really work. Well, that's like Masha, who would slip Vasya a carrot with a completely different gesture than some water. The placebo effect in this patient will become stronger, and again we will not be able to find out what the medicine really costs. How to deal with this problem?

- double blind method! - Masha blurted out as soon as possible, so that Vasya did not have time to interrupt her. - We will make sure that the doctor was also, as it were, blind! So that he does not know what medicine he gives to the patient. Let it be written somewhere which patient got what, and let the doctor not know this. He just gives all patients seemingly the same medicines - but one is real, and the other is a dummy.

Correctly! Well done, Masha! That is exactly what we will do. Vasya will be like a blind man, because we will blindfold him. And instead of the second blind man, we will have Uncle Misha, who does not know at all what we are doing here. Vasya, so that dad does not understand what we are doing here, and does not begin to influence the results, answer only yes or no. Yes - carrot broth, no - water. I agree?

Vasya nodded.

Wonderful! Mom said. - Mash, cook carrots!

Masha cleaned the carrot, threw it into a pot of water and put it on the fire. Mom at that time put the kettle on so that a glass of clean water, as hot as carrot broth, would be ready at the right time. Masha stood on tiptoe and took two identical opaque cups from the shelf. Mom, blocking herself from Vasya, wrote in advance on a piece of paper the sequence in which mugs of water and carrot broth would be served - so that this sequence could then be compared with Vasya's answers. Vasya looked at all this at once, both as a researcher and as a guinea pig - until his mother blindfolded his eyes with a scarf.

Miiish! she called into the other room when everything was ready.

Vasya's father appeared on the threshold. He glanced at the bowl of soup that everyone seemed to have forgotten about and said:

No, that's not the point, - Vasya's mother responded. - That is, Vaska, of course, does not eat soup. But we are now just sorting out whether he has the right to do so.

Vasya's father silently and questioningly looked around those present. He stared at the blindfold over Vasya's eyes for the longest time and most perplexedly.

You, most importantly, do not try to understand anything, - said Vasya's mother and blindfolded Vasya's father. - Now I will give you mugs with liquids, and you pass them to Vasya, and then back to me. Mash, get ready to write down Vasya's answers.

She consulted her paper, chose one of the mugs and handed it to Vasya's dad. Vasya's dad, blindfolded and with an impenetrable face, shoved the mug right under Vasya's nose.

Mor... I mean, yes! - said Vasya, and Masha wrote down this answer on her piece of paper.

Yeah, - drawled Vasya's dad. He had been initiated into the order of the experiment, and now the four of them had finally finished calculating the results. A sheet of paper was drawn into two columns - in the left, all the correct answers were marked with chopsticks, and in the right, the wrong ones. - And how can we understand it?

Ten percent - this means that you did not feel anything and invented everything, - Masha said to Vasya.

But no, - Vasya's mother suddenly responded. - Vice versa. It means that you feel great. If you didn't feel anything, your answers would be somewhere around fifty percent, that's where all the accidents sit. And ten percent, just like ninety percent, cannot come from ignorance, from random answers. This figure is not random, it means something.

And what? Vasya asked gloomily.

I know! Masha suddenly exclaimed. - It means ... It means that you feel everything very well, but only the other way around! When there is no carrot, you are sure that it is, and when there is, that it is not!

For a couple of minutes everyone was silent, considering this discovery, and suddenly Vasya turned white.

So all the soups I've eaten... All the ones I've smelled like carrot-free, they're...

Vasya, - my mother frowned in pain, - I haven’t put carrots anywhere for a hundred years, I already have nightmares about carrots.

Vasya slowly turned his gaze to the plate of cold soup.

And there are no carrots here either, - my mother answered his silent question.

And by the way, you promised something! Masha said.

Okay, - Vasya slowly moved the plate and scooped up the first spoon.

Enjoy your meal! Masha wished. - By the way, Aunt Marina! May I too? Another plate?

Insert for adults

The study of people's reactions to any impact, with the condition that the subjects are not initiated into the important details of the study. Method applied to exclude subjective factors, which can affect the result of the experiment.

double blind method- when not only the subjects, but also the experimenters do not know important details experiment until its completion. The double - blind method eliminates the experimenter 's unconscious influence on the subject and the experimenter 's subjectivity in evaluating the results .

Blinding is often used in medical trials to avoid biased results due to the placebo effect, which occurs in 5-10% of patients (if not more often). However, the method does not exclude the subjective assessment of the patient's condition by the doctor conducting the study. Therefore, there is a need to “dazzle” the doctor as well [Wikipedia].

AT recent decades In clinical practice, an evidence-based approach to decision making, which combines individual experience with the results of clinical trials, has become widely accepted. The rapid development of evidence-based medicine methods has also introduced doctors to the term "placebo", used in clinical trials of drugs as indispensable evidence that the test drug is better than "dummy".

Clinical studies of new drugs usually compare two groups of patients in whom the natural course of the disease and the nonspecific effects of therapy would be approximately equivalent. When active treatment is given to one group and placebo to the other, the differences are attributed to the specific effect of the therapy. Over the past 40 years, using this method, high results have been achieved in evaluating the effectiveness of many drugs.

There are two main methods used in clinical trials. This is an open method, when the drug is known to all participants in the treatment or trial, and a double-blind method, widely used in this area to exclude or minimize the influence of psychological factors on the results of a treatment or study. The double-blind placebo method is so named because neither the patient nor the attending physician knows which drug - drug or placebo - the patient is taking.

Placebo and double-blind have been mandatory since 1970 for evaluating the effectiveness of new drugs, testing various parties effects of well-known drugs, comparisons of related drugs. Thanks to this technique, it is constantly revealed that many drugs offered by advertising to practice as highly active turned out to be in fact ineffective. For example, it has been established that progabid is a derivative of gamma-aminobutyric acid (GABA), an inhibitory mediator in the central nervous system- does not outperform placebo. High hopes for progress in the treatment of epilepsy with this new drug did not materialize.

However, the use of a placebo as a comparator to prove the benefit of a new drug creates a number of problems in itself. For example, can a placebo be used in a drug trial for the treatment of acute and severe conditions (anaphylactic shock, ketoacidotic coma) or oncological diseases? Is it ethical to prescribe a placebo to one group of cancer patients and a new one to another? effective drug? Based on this, the ethical committees of European countries are very exacting in the design of clinical trials, requiring that the use of a placebo be irreproachably justified. Thus, according to the Declaration of Helsinki, in any medical research (including clinical trials), all patients, in particular those included in the control group, must be properly examined and receive appropriate treatment. Refusal in some pathological conditions from the use of placebo, when patients (from the control group) cannot be left without treatment, should be considered ethically justified. If the effectiveness of the drug is already established, a placebo-controlled trial should not be carried out even if required by the licensing authorities.

Modern requirements for conducting clinical trials include mandatory compliance with ethical standards, which, in addition to the decision of the ethical committee to conduct a trial, also includes the informed consent of the patient. However, the latter, as some studies show, can affect the outcome of the test. If there is a worsening condition after placebo, the patient should be withdrawn from the study or transferred to active treatment in the same trial. There are strong arguments in favor of the fact that participants in clinical trials in many cases are aware that they are prescribed a "pacifier". They draw such conclusions on the basis of the absence side effects. So, when conducting one clinical study, which compared the outcomes of the use of two antidepressants and placebo, 78% of patients and 87% of doctors correctly identified who took the drugs and who - their imitation. In other data, in 23 of 26 studies, the identification of patients treated with active and inactive drug was more accurate than random guessing.

In order to distinguish between the true pharmacological effect and the placebo effect when taking the drug, it is proposed to use four parallel groups instead of two. In addition to those taking the drug, the inactive drug, and receiving no treatment at all, an "active placebo" group can be formed. In this case, the patient also does not receive the investigational drug, but takes a drug that mimics it. side effects. For example, when testing antidepressants, atropine can be used. In this case, the subjects will feel one of the often developing side effects - dry mouth, and it will seem to them that they are receiving a specific treatment.