A clinical research study or a clinical trial is an experiment or observation performed on human subjects to generate data on the safety and efficacy of various biomedical and behavioral interventions. Blinding or masking refers to the withholding of information regarding treatment allocation from one or more participants in a clinical research study. It is an essential methodological feature of clinical studies that help maximize the validity of the research results.
Blinding covers any of the numerous participants of the clinical trial, e. Single-, double-, and triple-blinding are commonly used blinding strategies in clinical research. A single-blind study masks the subjects from knowing which study treatment, if any, they are receiving. A double-blind study blinds both the subjects as well as the researchers to the treatment allocation.
Triple-blinding involves withholding this information from the patients, researchers, as well as data analysts. Randomized, double-blind placebo-controlled trials involve the random placement of participants into two groups; an experimental group that receives the investigational treatment and a control group that acquires a placebo.
Neither the researchers nor the study subjects know who is getting the experimental treatment and who is getting a placebo. This type of clinical study ranks as the gold standard for the validation of treatment interventions. Unfortunately, blinding is not possible to achieve in all clinical trials.
For example, the method of drug delivery may not be amenable to blinding. An excellent clinical protocol may help ensure that within the ethical and practical constraints, blinding is achieved as effectively as possible. Bias refers to a deviation from the truth in the collection, analysis, interpretation, or publication of data, leading to false conclusions. Poor blinding of a clinical research study may lead to bias that may result in inflated effect size and increase the risk of type I error.
Even a small error in blinding may lead to a statistically significant result without any real difference between the study groups. Keeping both the researchers and the subjects blinded to treatment allows a double-blinded study to prevent the researchers from treating the study groups differently. The double-blinded study minimizes the risk of various types of biases, such as observer bias or confirmation bias, which may influence the results of the investigation. Unblinding may occur during any portion of the blinded clinical trial.
Unblinding that occurs before the conclusion of a trial may be a source of bias that the study should document and report.
It is the responsibility of all the healthcare professionals involved in a clinical trial, such as physicians, nurses, pharmacists, technicians, and data analysts, to maintain blinding as effectively as possible during the trial and to report any premature unblinding.
Many believe the placebo effect is psychological , due to either a real effect caused by belief or to a subjective delusion. For example: "If I believe the pill will help, it will help. For example, Irving Kirsch, a psychologist at the University of Connecticut, believes that the effectiveness of Prozac and similar drugs may be attributed almost entirely to the placebo effect.
The placebo effect can stimulate the brain into believing that the body is being healed, creating a natural mechanism that encourages better health. It may be an indication that the group receiving the placebo has a powerful internal mechanism that provides self-healing.
Some people can have a negative response to a placebo. When that outcome occurs, then the effects of a process or medication can receive a direct comparison to see if the real product is useful. Some people can have an adverse reaction to the placebo, even producing unwanted side effects as if they were taking a real medication. It all depends on how each person feels. A study involving people with asthma showed that using a placebo inhaler caused patients to do no better on breathing tests than sitting and doing nothing.
When researchers asked how they felt about using the product, they reported that the placebo was just as effective as the regular medicine they used. Randomization must use a structured process to be useful. The most common example of using randomization when assigning people to a group in a double-blind study is to flip a coin.
Assigning people who come to a specific location based on a day of the week can influence the results of the study unintentionally because there are other dynamics that control the behavior. That bias would be in the data without anyone recognizing its presence since it was placed there in the initial design. Most double-blind studies are too small to provide a representative sample. Even when you have hundreds, or sometimes thousands, of participants in this work, the results might not extrapolate to the general population.
There were more than 4, trials in progress for pain treatments in , but the only new approvals given were for formulations or updated dosages for existing medications.
Divergent results often create failure. The highest response rates for a placebo occur when researchers are looking into functional disorders like Irritable Bowel Syndrome. People who have other immune-response conditions like rheumatoid arthritis.
The FDA even notes that the placebo response is steadily growing in the general population. This disadvantage creates another limitation where the structure of a double-blind study may not provide useful information. Double-blind studies are an expensive effort to pursue. A double-blind study takes several months to complete so that researchers can look at each possible variable. It may be necessary to complete several efforts using different groups to collect enough data. When corporations look at the cost of these efforts, it can be an expense that reaches several million dollars before its completion.
Double-blind placebo studies are often called the gold standard for testing medications. This description is at its most powerful when studying new psychiatric medications since the placebo effect is a psychological benefit. It is a process that improves on the experiments that compare the response of someone taking a pill with those who do not. Since no one knows who is getting what in a double-blind study, the danger of a researcher accidentally communicating non-verbally about the expectation of an item to work or not gets eliminated.
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