A guide to clinical trial types
In Australia and around the world, clinical trials are a powerful engine behind countless medical advances. They help us test new treatments, tools, and techniques that can prevent, detect, diagnose, and treat a wide range of diseases and conditions.
However, clinical trials are just one part of a bigger research picture. Increasingly, the interventional approach of the clinical trial is being combined with other forms of clinical research, including quality of life assessments, behavioural research and other observational studies.
If you are planning a clinical trial, read on to understand the landscape of clinical research in Australia, including interventional and observational research, and where your work may fit into the picture.
Clinical trial types: A quick summary
- not all clinical trials are the same
- Interventional studies look at the safety and efficacy when a new intervention, such as a medical device, is introduced
- Observational studies monitor people as they are
- there are different types of clinical trials, including prevention, screening, diagnostic, treatment and quality of life trials.
Read on to learn about clinical trial types in more detail.
Table of contents:
First, what is clinical research?
Clinical research is a crucial part of Australia’s medical and healthcare system and our overall health and well-being as humans. Every new drug, vaccine, or surgical technique used in medicine today started as an experimental intervention tested by participants in a clinical study.
The focus of clinical research is developing new interventions that may improve the length and quality of people’s lives – or even help save lives.
It’s a broad category, spanning from clinical trials where participants receive an experimental medicine to observational studies in which patients answer surveys. Ultimately, it can be defined by two key subtypes: interventional or observational.
Interventional vs observational studies
The main form of interventional research is the clinical trial. In clinical trials, researchers test the safety and effectiveness of a range of interventions, most commonly new drugs, devices or medical treatments.
Interventional research both delivers and studies a change to its participants. In most clinical trials, participants are divided into groups, with one group receiving a placebo or the currently available standard of care, while the other group receives the new treatment. Their responses to this treatment are closely monitored by researchers.
Observational studies instead monitor people as they are. This research doesn’t involve any changes to the participant’s circumstances, including their treatment plan if they are a patient. They may or may not have received a new treatment beforehand. Overall the research process tends to be less time-consuming, with a focus on surveys or interviews.
These two forms of clinical research also have a range of subtypes, not all of which are mutually exclusive. For example, quality-of-life assessments are often considered part of a clinical (interventional) trial, even though they are observational in nature. Meanwhile, behavioural studies are usually observational but can involve an interventional component.
Types of clinical trials
Clinical trials are a type of clinical research, and they have a range of types or sub-types.
Prevention trials
Some clinical trials are preventative in nature; that is, they test a new intervention designed to prevent or lower the risk of disease. A prevention trial might test new medicines, vaccines, vitamins, or general lifestyle and health programs, including those involving diet and exercise.
Screening trials
Screening trials assess the effectiveness of new screening tools or methods. These interventions are designed to detect disease before people experience obvious physical symptoms.
Diagnostic trials
These trials test interventions designed to diagnose a disease in people with relevant signs or symptoms. Researchers are interested in developing more accurate and less invasive approaches to diagnosis.
Treatment trials
The treatment trial is a highly common, if not the most common, form of clinical trial. It tests a range of treatments, including new drugs, devices and different forms of therapy or surgery.
Researchers want to know if a treatment is safe, effective, and works as intended. They may test a new treatment by itself, a combination of treatments, or new ways of administering pre-existing treatments.
Quality of life trials
In Australia and globally, researchers undertaking one of the clinical trials above are increasingly likely to incorporate an additional step, usually towards the end of the process: a quality of life (QoL) assessment.
As the name would suggest, this research seeks to understand the quality of life and comfort levels of the people with the disease or condition being analysed. More observational in nature, it often involves questionnaires.
While this research can present some organisational or compliance issues (i.e. low return rates of questionnaires), it can contribute to a far better understanding of the health and well-being of participants, including the impact of pain, fatigue, and other symptoms of disease on their lives.
Other clinical research types
Clinical trials, and particularly randomised controlled clinical trials, are an optimal method for testing the safety, effectiveness and efficacy of new drugs and other treatments. But other forms of clinical research can also offer researchers crucial data and information – at a lower cost.
Observational research in more detail
Medical and health research involves a wide range of observational studies. As Julia FM Gilmartin-Thomas, Danny Liew and Ingrid Hopper (2018) note, they may be descriptive in nature, that is designed primarily to explain the characteristics of a particular group; analytical, or designed to answer cause-and-effect questions; or a combination of both.
Different types of observational studies include case reports or case series, ecological studies, cross-sectional studies, case-control studies or cohort studies. Researchers assess pre-existing data sets, often involving large groups of people, or assemble specific groups of participants.
Behavioural and psychosocial research
Also, observational in nature, behavioural and psychosocial research seeks to understand a wide range of factors that might affect a person’s risk of developing a disease or shape how they experience it.
For example, Australian behavioural researchers have studied the emotional and social impacts of cancer on patients and their families. Participants may be asked to undertake interviews or complete surveys about various lifestyle factors, including diet, alcohol intake and exercise.
Participants in behavioural research may also be involved in programs designed to intervene with – or change – lifestyle factors. For instance, they may be offered free therapy, exercises classes or healthy eating seminars.
Whether it is observational, interventional or a combination of both, this research will seek to reduce the risk of cancer or other diseases and gain a better understanding of how people cope with its impacts.
Translational research
Translational research creates a bridge between laboratory and clinical research or between clinical research and medical practice. Its primary aim is to move new treatments from “bench to bedside” – or from the research stages to practice – as quickly and effectively as possible.
It can take years, sometimes even decades, for the innovations of clinical trials or observational studies to be translated into use for real-world populations. Translational researchers work with policy-makers, academics, health professionals and other stakeholders to accelerate this process.
Investigator-led trials: key types
Investigator-led trials, also known as investigator-initiated trials, are usually undertaken by health institutions or within an academic setting. They are funded through grants or sponsorship from government agencies and departments, research groups, foundations or charities.
Conversely, industry-led trials are initiated and funded by commercial entities like pharmaceutical, biotechnical or medical device companies.
Both investigator-led and commercially sponsored clinical trials test a wide range of interventions, but they differ in their approach and scope.
Investigator-led trials
Investigator-led clinical trials of all types are common. However, researchers are more likely than their commercial counterparts to address niche research questions or to test treatments for less common conditions. They also typically have less funding, which can affect the scope, size and length of their research.
Industry-led trials
These are often treatment trials for ‘blockbuster’ drugs that will be widely known and used. They may be more likely to incorporate observational studies, particularly in later phases after a new drug has been approved. These late-stage studies help satisfy government or regulatory requirements for ongoing monitoring of the drug in the real world.
Frequently asked questions
In some forms of interventional clinical research, particularly treatment trials, participants may consent to receiving new drugs or treatments. Some clinical trials may also involve biospecimen studies, whereby participants consent to provide biological materials such as blood, tissues, or cells. These are stored in a biorepository and used for laboratory research. Research of a more observational nature may require participants to undertake surveys or interviews in which they describe their behaviours, practices or opinions regarding healthcare or medical matters.
The safety and well-being of participants is a leading priority for all clinical research in Australia, including clinical trials. From sign-up to completion, participants receive clear information about the type of research they are participating in, what is involved, and what they might need to do or bring. Clinical teams must also adhere to a range of national and international ethics guidelines, laws and codes of conduct and be approved by a Human Research Ethics Committee (HREC) before proceeding.
