The research team may include :. Some common locations include:. This depends on what is being studied, among other factors. Some trials last days, while others continue for years.
There are different types of study, and different ways of organizing them. Here are some study types. A cohort study is an observational study in which the study population, or cohort, is selected. An individual could be chosen because they smoke. They may then be followed forward in time to see how likely they are to develop a disease, compared with other people.
This type of study is used to study the effect of suspected risk factors that cannot be controlled experimentally, such as the impact of smoking on lung cancer. Researchers compare people with a condition and those without it. Working backward through time, they identify how the two groups differ. Case-control studies are always retrospective — looking backward — because they begin with the outcome and then trace back to investigate exposures. The main advantages of case-control studies are:.
In a nested case-control study, the groups — cases and controls — come from the same study population, or cohort. Nested case-control studies are less costly and less time-consuming when compared with a cohort study.
Incidence and prevalence rates of the disease can occasionally be projected from a nested case-control cohort study. This is not possible from a simple case-control study, as the total number of exposed individuals and the follow-up times are usually unknown. An ecological study looks at the relationship between exposure and outcome of the population or community. Apart from observational studies, there are also experimental studies, including treatment studies.
A randomized controlled trial RCT randomly allocates individuals either to receive or not receive a particular intervention. This is the most effective study type for identifying which treatment works best. It reduces the influence of external variables. An adaptive design method is based on collected data.
It is both flexible and efficient. Modifications can be made to the trial and the statistical procedures of ongoing clinical trials. This type of trial is frequently used when an RCT is not logistically feasible or ethical. Hierarchies of evidence make it possible to rank various research methods according to the validity of their findings. Not all research designs are equal in terms of the risk of error and bias in their results.
Some methods of research provide better evidence than others. Below is an example of the hierarchy of evidence-based medicine in the form of a pyramid , ranging from a lower quality of evidence at the bottom to high-quality evidence at the top.
Medical research studies are divided into different stages, called phases. For drug testing, these are defined by the FDA. Early phase trials investigate the safety of a drug and the side effects it may cause.
Later trials test if a new treatment is better than an existing treatment. Phase 0 is an exploratory phase that helps provide clinical information for a new drug at an earlier phase. This phase:. After phase 0, there are four more phases of trials in humans. These often overlap. Phases 1 through 3 take place before a license is granted.
If phase 2 has confirmed the effectiveness of a drug, the FDA and sponsors will discuss how to conduct large-scale studies in phase 3. After this phase, the complete information on the new drug is submitted to the health authorities.
If the FDA approve the product for marketing, post-marketing requirement and commitment studies are conducted. The FDA use these studies to collect further safety, efficacy or optimal use information about the product. An NDA includes:. Facility inspection : The FDA inspect the facilities where the drug will be manufactured. Drug approval: FDA reviewers either approve the application or issue a response letter. Phase 4 trials take place after the drug has been approved for marketing.
They are designed to include:. After the FDA approves a drug, the post-marketing stage begins. The sponsor, usually the manufacturer, submits periodic safety updates to the FDA. For example we did some new drugs in rheumatoid arthritis, which were called anti-TNFs [tumour necrosis factor], things like etanercept.
And to do that we needed to get the evidence for all the old drugs, and I was very shocked, having had rheumatoid arthritis for years and tried most of these drugs, to actually find that the evidence base for all of them was extremely poor. There was only one with really Well, has a trial been done on it?
Well, yes it has, and what does it show? There are so few numbers of people dying it could so easily have occurred by chance. Phase 1 and Phase 2 trials Many clinical trials especially for new drugs are carried out in a number of stages, or phases. When a new treatment is first developed, such as a new cancer drug, it will be tried first in a few people to get an idea how safe it is.
They may be healthy volunteers, who are given a compensation payment for taking part, or they may be people who are ill, perhaps people who have already tried all the usual treatments. This is called a Phase 1 trial. At this stage, the treatment is usually given to all those taking part, and it is not being compared against some other treatment see below. Anthea describes what a Phase 1 trial is. No-one knows what the side effects will be and whether And you know, I have been closely monitored.
Early phase studies are carried out precisely because we need to find out about possible risks and side effects before giving the treatment more widely. By the time a drug reaches Phase 2, researchers will know more about it. In Phase 2 the aim is to test the new drug in a larger group of people to better measure safety and side effects and see if there are signs of positive effects in patients. Phase 2 trials may or may not involve comparison with another treatment see below.
Tom was invited to join a non-randomised Phase 2 trial of chemotherapy for inoperable lung cancer So this young lady asked me if I would like to take part in a clinical drug trial, and she explained the situation. Went along and, you know, a medical, a check-up to see that I was okay to take part in a trial, so I was accepted into the trial, which I believe was a phase 2 trial.
It was six months of chemo. It ended up there was a kind of group of us of four or five. In Phase 2 trials we can start to get some idea of whether a treatment works for some people, and what kind of side effects they experience. But at this stage the numbers of people included are still too small to give us firm evidence about its effects and that any observed change is not just happening by chance. This is why Phase 3 trials are needed. Phase 3, randomised clinical trials Phase 3 trials are usually large, and may include hundreds or even thousands of patients.
They often compare the effects of newer drugs or treatments with standard treatments if there are any. They provide a better test of whether new treatments work better than existing treatments, and firmer evidence about how common and serious any side effects are.
Almost all Phase 3 trials are randomised clinical trials RCTs. In an RCT, one group of people, the experimental group, is given the new treatment. The other group, called the control group, is given the standard treatment. If no standard treatment exists, the control group may not be given any specific treatment or may be given a placebo. Some trials may compare more than two groups. A placebo is a treatment, with no active ingredient, which is designed to appear very like the treatment being tested.
There are several ways in which the results of trials can be made as reliable and accurate as possible. In a blind trial the participants are not told which group they are in. This is because if they knew which treatment they were getting it might influence how they felt or reported their symptoms. Some trials are double-blind, which means that neither participants nor the doctors and others treating them know which people are getting which treatments.
Here Wendy describes a typical RCT design comparing standard treatment for bowel cancer with an extra chemotherapy drug. Wendy was asked to take part in a year-long trial of chemotherapy for bowel cancer. She thought Just before Christmas I went to a major hospital away from where we lived, and I had an appointment there to see one of the oncology team. I also saw a professor, who was leading a trial.
So I was then told the, the plan was to have six months of chemotherapy. Alongside that I was offered the chance, if I wanted to, to go into this clinical trial. I asked a few pointed questions. It was all taped, by the way, so we could take the tape away, listen to all the questions, listen to all the things the professor had mentioned. Doctors and hospital staff involved in clinical trials are continually trained to provide best practice patient care. Australian clinical trials are recognised internationally as providing very high quality patient care.
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