Clinical Research Study Design


A clinical research study design is a description of how the research will be conducted. It is important to think over every small detail in advance. If the design of the study is incorrect, all work will fail in the bud.

Pavlov's Dog Principle

Ivan Pavlov described an experiment in which morphine was injected under the skin of dogs. The first reaction was vomiting, followed by falling asleep. By repeating the procedure on a regular basis, the researchers ensured that vomiting in animals was caused by the introduction of any indifferent liquid under the skin.

This phenomenon is known as the placebo effect. It helps representatives of pseudo-medicine to successfully conduct business and scientists — to check whether the positive effects of a drug are due to its real action or a conditioned reflex, the power of suggestion. Patients are divided into two groups, and one is given a new medicine, the other — a "dummy." Sometime later, the result is to be evaluated. The scheme is simple, convenient, and effective, but there is one complication. Sometimes, if the patient receives a placebo instead of a drug, it leads to fatal consequences. In such cases, it is unethical to use the placebo control, but there are alternatives.

Blinding in Clinical Trials

When the appearance of two drugs under active control differs, they resort to the blinding procedure. For example, if the examined drug is a pill and the control drug is the inhaler, then the patient and the doctor can easily guess what drug it is, and blinding will not work. Therefore, some patients receive drugs in pills and the placebo in the inhaler, while others receive a drug in the inhaler and a dummy in the pill. Thus, the combination of drugs in each of the two groups looks exactly the same.

In general, there are three levels of blinding. The choice depends on the study characteristics and the possible influence of different participants on the result.

Open study means that no blinding is used. Examples of open studies.

If there are no other drugs for treating the disease, or the drug needs to be compared with other treatment methods (for example, surgery), you can use historical control (control of archival statistics). The outcomes of patients receiving a new drug are compared with the statistics already available.

Randomization in Clinical Trials

Dividing study participants into treatment and control groups should be performed correctly. An extremely exaggerated but clear example: imagine a pharmaceutical company that decided to bring a new memory-enhancing drug to the market. The study involves 100 patients, and they were divided into two groups of 50 people; some are given the miracle drug, others - chalk pills. It just turned out that most healthy young people were included in the treatment group. While in the control group, there were many elderly people, some having the first symptoms of Alzheimer's disease. A tricky question: Will the new drug be "more effective" than the placebo?

In real life, of course, the situation is not always so simple and obvious. Sometimes, it seems that there is no difference between the groups, but nuances that greatly distort the final picture, escape notice. Often, people who conduct research "select" the "necessary" participants unconsciously, especially when they really want to get a positive result.

In order to avoid mistakes, it is necessary to distribute the study participants into groups randomly, blindly. This process is called randomization. And it can be different.

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