3. Types of Clinical Trials Click to return to the Clinical Trial main page What are clinical studies or trials? Clinical trials are medical research studies that involve people. Trials can evaluate various interventions, which may be medical, surgical, or behavioural. Clinical trials are medical research studies that involve people. Trials can evaluate various interventions, which may be medical, surgical, or behavioural. The primary objectives of these trials are to determine the safety and effectiveness of newly proposed interventions, such as treatments, devices, and dietary approaches. They also serve to investigate potential risk factors or symptoms associated with certain conditions. Before a clinical trial starts with humans, years of work have already occurred in laboratories. Types of Clinical Trials There are two main groups of clinical trials: interventional and observational. Within these two groups, there are different types of trials, including pilot and feasibility studies, where researchers conduct miniature versions of larger studies before a large trial occurs. Interventional Trials They aim to find out more about a particular intervention or treatment. A computer divides the participants into different treatment groups so that the researchers can compare the results. Observational Trials These studies aim to discover what happens to people in different situations. The research team observes the people taking part, but they don't influence what treatments people have. These studies can examine risk factors or follow people with a condition over time to observe how it progresses. Researchers do not organise participants into distinct treatment groups in observational studies because there are no treatments. Feasibility studies They are designed to determine whether the main study is possible. For example, they will test whether professionals and participants are willing to participate and how long they think it will take to collect and analyse the information for that trial to work. Pilot Studies These are miniature versions of the main trial. Pilot studies test that all the main parts of the study work together. For example, they look at previous investigations and work together to identify the correct group of patients. These trials also help answer the research question, which researchers may include in the results of a primary study. Prevention and screening studies Depending on whether researchers are investigating how to prevent certain conditions or new methods of investigating and diagnosing conditions early, they divide their research into prevention and screening trials. Screening trials These trials study individuals for the early signs of diseases before they have any symptoms. They are looking at new methods of investigating and diagnosing conditions in people very early in the disease process, who may not have symptoms and have not been diagnosed yet. They learn if new tests are reliable enough to detect particular diseases, or they may try to find out if there is an overall benefit in picking up the disease early. Prevention trials These studies investigate whether a treatment can prevent disease. The trials can involve the general population or individuals at higher risk of developing a specific condition, such as those with a strong family history of Alzheimer's disease or cancer. The goal is to determine if the treatment can prevent these people from developing the condition in the future. Multi-Arm Multi-Stage (MAMS) Trials MAMS are complex trials with several different treatment groups that may change as the study progresses and a standard treatment group (control group) that stays the same throughout the study. MAMS study allows people to change their treatment throughout the study, for example, by trying new medications that become available on the market. This means that the drug company doesn't have to design a new trial every time something changes on the market, which allows it to get results quicker. The research team may decide to stop recruiting people to a particular group if they have enough people to start examining the results or if early results show the treatment isn't working as well as they'd hoped. Cohort Studies A cohort study follows a group of people over a prolonged period of time, looking at risk factors for developing certain conditions. Some of these studies can run for 20-30 years. A research team may recruit people without diseases and collect information about them for several years. The researchers see who in the group develops the disease and who doesn't. They investigate whether the people who develop the disease have anything in common. Cohort studies are very useful ways of discovering more about risk factors but are expensive and time-consuming. They can be used when testing a theory in any other way is impossible. For example, this type of study would be used to see if smoking is linked to cancer. Case-Control Studies These studies look at two groups exposed to a specific risk factor: people with a disease (Cases) and people who don't have a disease (Controls). The groups have an even balance of general attributes such as age or gender. Case-control studies are helpful, quicker, and cheaper than cohort studies. However, the results may be less reliable, as people may need to accurately remember events that happened years ago, which affects the results. Association Vs Cause Just because a risk factor is associated with a disease doesn't mean the risk factor causes the disease. For example, a case-control study may show that people with a lower income are more likely to develop a disease. But this doesn't mean that the income level itself causes the disease. It may mean they have a poor diet or are more likely to smoke. Cross-Sectional Studies These studies look at people at a set time point or over a short period of time to see who has been exposed to a specific risk factor and who has developed a specific disease. For example, they can look at individuals with lung cancer and see how many of them smoked in the past. Cross-sectional studies are quicker and cheaper, but the results can be less useful because they don't consider people who can develop the diseases later and rely on people's memories. Sometimes, researchers first do a cross-sectional study to find a possible link. Then, they do a case-control or cohort study to examine the issue more thoroughly. Navigate to other pages about clinical studies: 1. Clinical Trials Explained: Learn the basics 2. Clinical Trials Process: Start to Finish 3. Types of Clinical Trials 4. Accuracy and Safety in Clinical Trials 5. Phases Of Clinical Trials 6. Clinical Trial: Key Participant Information 7. Clinical Trials Community Questions Manage Cookie Preferences