Clinical Trials or Studies Involving a Drug, Medical Device, or Natural Health Product

Clinical trial definitions and types

As defined in the TCPS 2 (2022), “a clinical trial is any investigation involving participants that evaluate the effects of one or more health-related interventions on health outcomes. Interventions include but are not restricted to, drugs, radiopharmaceuticals, cells and other biological products, surgical procedures, radiologic procedures, devices, genetic therapies, and psychotherapies. Clinical trials may also include questions that are not directly related to therapeutic goals (e.g., drug metabolism) in addition to those that directly evaluate the treatment of participants.”

Note that the TCPS 2 (2022) uses the terms ‘clinical trial’ and ‘clinical study’ interchangeably. 

Types of clinical trials

1. Treatment Trials test experimental treatments, new drugs, combinations of drugs, medical devices, natural health products, or new approaches to surgery or therapy. An example of an experimental treatment is an investigational contact lens; contact lenses are medical devices.
2. Prevention Trials test ways to prevent disease or prevent a disease from returning. The approaches may include drugs, vitamins, minerals, natural health products, educational programs, and lifestyle/behavioural change. Examples of specific approaches include smoking prevention programs, smoking cessation, and the use of echinacea (plant extract used to boost the immune system).
3. Quality of Life Trials test or explore ways to improve comfort and the quality of life for individuals with a chronic illness, disability, or condition. For example, trials may look at better ways to manage or prevent nausea and fatigue caused by cancer treatments.
4. Diagnostic Trials are designed to find better tests or procedures for diagnosing a particular disease or condition. For example, a trial to determine if ultrasound is more effective than mammography in detecting breast cancer.
5. Screening Trials are conducted to test the best way to detect certain diseases or health conditions. For example, a trial to test a new medical imaging method or a new blood test that would detect markers that indicate cancer may be present in a person’s body.

Phases of a clinical trial

Typically, clinical trials are conducted in four sequential phases with each phase involving a larger sample of participants.

1. Phase I trials are conducted to assess safety. Usually, the testing involves a small number (e.g., 20-80) of healthy participants.
2. Phase II trials assess effectiveness and further evaluate safety. This phase of the trial usually involves participants who have the disease or condition under investigation. Normally participants are randomly assigned to groups or conditions, with one condition being the treatment (program, drug, etc.) under consideration and at least one comparison condition. Phase II studies involve a limited number (e.g., 100-300) of closely monitored participants.
3. Phase III trials involve a large number (e.g., 1,000-3,000) of participants, and are intended to gather further evidence of effectiveness, monitor adverse reactions, and gather additional evidence of effectiveness for specific indications. Usually, these trials involve multiple sites.
4. Phase IV trials may explore specific effects, or be designed to determine effects on morbidity and mortality or on specific populations. For drugs, natural health products, and medical devices, Phase IV trials are conducted after the drug, medical device, or natural health product is on the market.

Find more information about Guidance for VIU Researchers Interested in Conducting Clinical Research, Health Canada Review, and Resources to Support BC Researchers.