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A randomized controlled trial (RCT) is a form of clinical trial, or scientific procedure used in the testing of the efficacy of medicines or medical procedures. It is widely considered the most reliable form of scientific evidence because it is the best known design for eliminating the variety of biases that regularly compromise the validity of medical research. In medicine, a clinical trial (synonyms: clinical studies, research protocols, medical research) is a research study. ...
Medicine is the branch of health science and the sector of public life concerned with maintaining human health or restoring it through the treatment of disease and injury. ...
Scientific method refers to a body of techniques for the investigation of phenomena and the acquisition of new knowledge of the natural world, as well as the correction and integration of previous knowledge, based on observable, empirical, measurable evidence, and subject to laws of reasoning. ...
For Wikipedias policy on avoiding bias, see Wikipedia:Neutral point of view. ...
Sellers of medicines throughout the ages have had to convince their patients that the medicine works. As science has progressed, public expectations have risen, and government health budgets have become ever tighter, pressure has grown for a reliable system to do this. Moreover, the public's concern for the dangers of medical interventions has spurred both legislators and administrators to provide an evidential basis for licensing or paying for new procedures and medications. In most modern health-care systems all new medicines and surgical procedures therefore have to undergo trials before being approved. Oral medication A medication is a licenced drug taken to cure or reduce symptoms of an illness or medical condition. ...
A typical modern surgical operation For other uses, see Surgery (disambiguation). ...
Trials are used to establish average efficacy of a treatment as well as learn about its most frequently occurring side-effects. This is meant to address the following concerns. First, effects of a treatment may be small and therefore undetectable except when studied systematically on a large population. Second, biological organisms (including humans) are complex, and do not react to the same stimulus in the same way, which makes inference from single clinical reports very unreliable and generally unacceptable as scientific evidence. Third, some conditions will spontaneously go into remission, with many extant reports of miraculous cures for no discernible reason. Finally, it is well-known and has been proven that the simple process of administering the treatment may have direct psychological effects on the patient, sometimes very powerful, what is known as the placebo effect. Adverse effect, in medicine, is an abnormal, harmful, undesired and/or unintended side-effect, although not necessarily unexpected, which is obtained as the result of a therapy or other medical intervention, such as drug/chemotherapy, physical therapy, surgery, medical procedure, use of a medical device, etc. ...
This article is about modern humans. ...
Remission is the state of absence of disease activity in patients with known chronic illness. ...
The placebo effect (Latin placebo, I shall please), also known as non-specific effects and the subject-expectancy effect, is the phenomenon that a patients symptoms can be alleviated by an otherwise ineffective treatment, since the individual expects or believes that it will work. ...
Types of trials Randomized trials are employed to test efficacy while avoiding these factors. Trials may be open, blind or double-blind.
Open trial In an open trial, the researcher knows the full details of the treatment, and so does the patient. These trials are open to challenge for bias, and they do nothing to reduce the placebo effect. However, sometimes they are unavoidable, particularly in relation to surgical techniques, where it may not be possible or ethical to hide from the patient which treatment he or she received.
Blind trials
Single-blind trial In a single-blind trial, the researcher knows the details of the treatment but the patient does not. Because the patient does not know which treatment is being administered (the new treatment or another treatment) there should be no placebo effect. In practice, since the researcher knows, it is possible for them to treat the patient differently or to subconsciously hint to the patient important treatment-related details, thus influencing the outcome of the study.
Double-blind trial In a double-blind trial, one researcher allocates a series of numbers to 'new treatment' or 'old treatment'. The second researcher is told the numbers, but not what they have been allocated to. Since the second researcher does not know, they cannot possibly tell the patient, directly or otherwise, and cannot give in to patient pressure to give them the new treatment. In this system, there is also often a more realistic distribution of sexes and ages of patients. Therefore double-blind (or randomized) trials are preferred, as they tend to give the most accurate results. Double-blind describes an especially stringent way of conducting an experiment, usually on living, conscious, human subjects. ...
Triple-blind trial Some randomized controlled trials are considered triple-blinded, although the meaning of this may vary according to the exact study design. The most common meaning is that the subject, researcher and person administering the treatment (often a pharmacist) are blinded to what is being given. Alternately, it may mean that the patient, researcher and statistician are blinded. These additional precautions are often in place with the more commonly accepted term "double blind trials", and thus the term "triple-blinded" is infrequently used. However, it connotes an additional layer of security to prevent undue influence of study results by anyone directly involved with the study. The mortar and pestle is an international symbol of pharmacists and pharmacies. ...
For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ...
Controlled aspect The 'controlled' aspect comes from three main sources. The first is another member of the research team, who will typically review the test to try to remove any factors which might skew the results. For example, it is important to have a test group which is reasonably balanced for ages and sexes of the subjects (unless this is a treatment which will never be used on a particular sex or age group). The second source of control is inherent in having a 'control' group, that is, a group which is undergoing the same routine (seeing a doctor, taking pills at the same time, etc.) but is not receiving the same treatment. This control group will be receiving either no treatment (e.g., sugar pills) or will be receiving the current standard treatment (if, for example, it would be unethical not to treat their ailment at all). The third source of control is via peer review and/or review by government regulators, who will examine the trial when it is presented for publication or when the drug manufacturer applies for a licence for the drug.
The importance of having a control group cannot be overstated. Merely being told that one is receiving a miraculous cure can be enough to cure a patient—even if the pill contains nothing more than sugar. Additionally, the procedure itself can produce ill effects. For example, in one study on rabbits where these subjects were receiving daily injections of a drug, it was found that they were developing cancer. If this was a result of the treatment, it would obviously be unsuitable for testing in humans. Because this result was reflected equally between the control and test groups, the source of the problem was investigated and it was shown in this case that the administration of daily injections was the cancer risk—not the drug itself. Genera Pentalagus Bunolagus Nesolagus Romerolagus Brachylagus Sylvilagus Oryctolagus Poelagus Rabbits are small mammals in the family Leporidae, found in many parts of the world. ...
When normal cells are damaged beyond repair, they are eliminated by apoptosis. ...
The analysis of the trial results is a great skill in itself, and pharmaceutical firms employ groups of statisticians to try to make sense of the data. Likewise, regulators pay keen attention to the statistics, which can be used to hide serious deficiencies in the effectiveness of a treatment. A graph of a bell curve in a normal distribution showing statistics used in educational assessment, comparing various grading methods. ...
Outcome-adaptive randomization For a randomized trial in human subjects to be ethical, the investigator must believe before the trial begins that all treatments under consideration are equally desirable. At the end of the trial, one treatment may be selected as superior if a statistically significant difference was discovered. Between the beginning and end of the trial is an ethical grey zone. As patients are treated, evidence may accumulate that one treatment is superior, and yet patients are still randomized equally between all treatments until the trial ends.
Outcome-adaptive randomization is a variation on traditional randomization designed to address the ethical issue raised above. Randomization probabilities are adjusted continuously throughout the trial in response to the data. The probability of a treatment being assigned increases as the probability of that treatment being superior increases. The statistical advantages of randomization are retained, while on average more patients are assigned to superior treatments.
Difficulties A major difficulty in dealing with trial results comes from commercial, political and/or academic pressure. Most trials are expensive to run, and will be the result of significant previous research, which is itself not cheap. There may be a political issue at stake (compare MMR vaccine) or vested interests (compare homeopathy). In such cases there is great pressure to interpret results in a way which suits the viewer, and great care must be taken by researchers to maintain emphasis on clinical facts. The MMR vaccine is a mixture of live but attenuated viruses, administered via injection for immunization against measles, mumps and rubella. ...
Samuel Hahnemann, the father of homeopathy Homeopathy (also spelled homœopathy or homoeopathy) from the Greek words όμοιος, hómoios (similar) and πάθος, páthos (suffering), is a system of alternative medicine that treats like with like, using remedies that would, in healthy individuals, produce similar symptoms to those it would treat...
Most studies start with a 'null hypothesis' which is being tested (usually along the lines of 'Our new treatment x cures as many patients as existing treatment y') and an alternative hypothesis ('x cures more patients than y'). The analysis at the end will give a statistical likelihood, based on the facts, of whether the null hypothesis can be safely rejected (saying that the new treatment does, in fact, result in more cures). Nevertheless this is only a statistical likelihood, so false negatives and false positives are possible. These are generally set an acceptable level (e.g., 1% chance that it was a false result). However, this risk is cumulative, so if 200 trials are done (often the case for contentious matters) about 2 will show contrary results. There is a tendency for these two to be seized on by those who need that proof for their point of view. In statistics, a null hypothesis is a hypothesis set up to be nullified or refuted in order to support an alternative hypothesis. ...
In statistics, the Alternative Hypothesis is the hypothesis proposed to explain a statistically significant difference between results, that is if the Null Hypothesis has been rejected. ...
See also Randomization is the process of making something random. ...
Medicine is the branch of health science and the sector of public life concerned with maintaining human health or restoring it through the treatment of disease and injury. ...
One may be faced with the problem of making a definite decision with respect to an uncertain hypothesis which is known only through its observable consequences. ...
The topics below are usually included in the area of interpreting statistical data. ...
Evidence-based medicine (EBM) is a medical movement based upon the application of the scientific method to medical practice, recognizing that many long-established medical traditions are not yet subjected to adequate scientific scrutiny. ...
Systematic reviews are named as the highest level of medical evidence, by evidence based medicine professionals. ...
A meta-analysis is a statistical practice of combining the results of a number of studies. ...
Double-blind describes an especially stringent way of conducting an experiment, usually on living, conscious, human subjects. ...
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