Researchers set up a trial to test the effects of a drug on a specific group of people while measuring another for reference. The United States Food and Drug Administration FDA will generally only approve a new treatment as safe and effective for wider use if results indicate that the effects of the drug are in line with its claims, and if these benefits occur without causing unsafe adverse effects. However, between and , 76 applications received approval without undergoing an RCT.
Discussion continues as to whether a product is definitely safe without passing an RCT. Randomization prevents the skewing or deliberate manipulation of results. Both participants and research scientists can influence results unless the researchers assign participants to groups at random.
Scientists refer to this skewing of results as selection bias. An RCT gets rid of selection bias by removing the element of choice. For example, without randomization, scientists may consciously or subconsciously assign patients to the group receiving the active treatment if they look more likely to benefit from the experimental treatment. This could make a treatment appear more beneficial than it actually is.
On the other hand, if scientists are looking to demonstrate the ineffectiveness or potential danger of a certain treatment, they may assign participants who have a higher risk of complications or a lower chance of success to the group receiving the treatment.
The risk of selection bias may also be high in trials by researchers who have received either direct or indirect funding from a pharmaceutical company looking to prove the efficacy and safety of a new drug.
For this reason, researchers must disclose any potential conflict of interest when conducting a clinical trial, as pharmaceutical manufacturers have a clear financial interest in achieving positive results.
Knowing which participants are getting the experimental drug can result in sound motivations as well as questionable ones.
Doctors could have a well-intentioned influence over the results. Even selection bias with good intentions, such as researchers having concerns about the safety of a drug, is scientifically unsound. If the active treatment seems to be producing severe side effects, for example, doctors may try to protect certain types of participant from the drug.
Treating different subjects in different ways during the trial reduces the integrity of like-for-like comparisons, giving false results. Randomization removes bias and truly allows for a direct comparison between two groups in a trial, providing a real representation of how the drug will react with the wider population after distribution. The purpose of a control group in a randomized controlled trial is to help reduce the likelihood that any benefits or risks that the researchers identify during the trial occur due to factors outside of the experimental treatment.
The absence of a control group would mean that the researchers could not attribute any improvement or decline in health to the drug or treatment. Others factors about the clinical trial could explain the results. Without comparing what happens in similar participants facing similar conditions without getting the new drug, accurate measurement of any observed health changes would not be possible.
A control group is a key part of large trials. Enough people must be taking part to ensure that chance differences and unusual circumstances do not have a decisive effect on the results. Researchers normally match people in a control group for age, sex, and ethnicity, along with any other factors that may influence the effect of a drug or treatment, such as body weight , smoking status, or comorbidities.
The control group may receive a placebo. A subcommittee of NICE's board that advises staff on identifying risks to the organisation and how to reduce them. Its work includes making sure NICE follows legislation on issues such as health and safety and data protection, and advising on preventing errors in published guidance. Random allocation See Randomisation. The ability to get the same or similar result each time a study is repeated with a different population or group. Before interventional procedures, medical technology or diagnostics guidance is published, consultees can ask for a 'resolution' if they think that the guidance is inaccurate or the process for developing interventional procedures guidance has not been followed.
During the resolution process any concerns raised by the consultees are investigated. A research study that focuses on the past and present. The study examines past exposure to suspected risk factors for the disease or condition. Unlike prospective studies, it does not cover events that occur after the study group is selected. A summary of the evidence in a number of different individual studies, with conclusions about their findings.
A review may or may not be systematically researched and developed. A document that outlines the background, objectives and planned methods for a systematic review. Randomised controlled trials RCTs are one type of clinical trial. RCTs aim to find out which treatment is best by making a fair comparison between: a new treatment and an existing treatment two or more existing treatments a new treatment and no treatment, or a placebo where there is no existing treatment.
RCTs - Comparing Treatment In an RCT, two or more groups of people are compared: one or more experimental group s who receive a new treatment, and a control group, who receive the current standard treatment which might be the best existing treatment, no treatment or a placebo. Similar groups of people It is important that in an RCT, the two or more groups of people in a trial are as similar as possible, except for the treatment they receive.
This is important because it means that researchers can be sure that any differences in outcomes between the groups are only due to the treatment received.
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