What is clinical research?
Clinical research is a type of medical study that helps doctors and scientists understand diseases and find better ways to prevent, diagnose, and treat them. By studying people’s health, researchers can learn how different treatments work and improve care for future patients.
Clinical research can include both observational studies and interventional studies also known as clinical trials.
What is the difference between observational and interventional studies (clinical trials)?
In observational studies, scientists do not test new treatments or interventions. They just simply observe. Scientists would not assign a new treatment but might make observations for a treatment that patients are already using as a part of their regular health care.
Interventional studies or clinical trials, on the other hand, allow scientists to test new ways to prevent, detect, and treat disease. Interventional studies may involve experimenting with new drugs, medical devices, or new ways to use existing treatments. Some clinical trials focus on behavior changes (behavioral intervention) that could improve health. For example, a trial might study whether a mobile app can help people with alcohol-associated liver disease (ALD) reduce or quit drinking.
What are the types of observational studies? 
Observational clinical studies include:
Case Studies: Researchers conduct an in-depth analysis of a single individual, group, or event to explore unique circumstances, rare conditions, or specific interventions. Case studies provide detailed insights but are limited in generalizability due to their focus on specific contexts.
Case-Control Studies: These compare people with a condition (cases) to those without it (controls) to figure out what might have caused the condition.
Cohort Studies: Researchers follow a group of people over time to see how certain factors (like lifestyle or environment) affect their health.
Cross-Sectional Studies: Researchers look at data from a single moment in time to understand how common a condition or exposure is.
Ecological Studies: These focus on groups of people (not individuals) to explore patterns or connections between factors and health outcomes.
What are the phases of clinical trials?
Clinical trials have five key phases:
Early Phase I: Fewer than 20 participants. Tests a new intervention on a very small group to assess initial safety and how the body processes it. This is often the first step to ensure the treatment is safe enough for further testing.
Duration: A few months to a year.
Phase I: 20–100 participants. Tests the intervention on a small group of healthy volunteers or patients to evaluate safety, determine the right dosage, and identify side effects. This phase helps ensure the treatment is safe before testing on larger groups.
Duration: Several months to a year.
Phase II: 100–300 participants. Expands testing to a larger group of patients to see how well the treatment works for its intended purpose while continuing to monitor safety.
Duration: Typically 1–2 years.
Phase III: 300–3,000 participants. Involves a much larger population to confirm how effective the treatment is, monitor side effects, and compare it to existing treatments. This is the final step before seeking FDA approval.
Duration: Often 3–5 years.
Phase IV: Thousands of participants. Conducted after FDA approval, this phase monitors the treatment’s long-term safety and effectiveness, including any rare side effects, in the general population.
Duration: Ongoing, often lasting many years.
Is a clinical trial right for me?
Every trial has specific eligibility criteria. Speak with your doctor and the clinical study team to determine if joining aligns with your health needs and lifestyle. Our Guide can help you ask important questions before signing up. Your decision to join is entirely voluntary, and you can withdraw at any time.
How can I find a clinical trial near me?
The Wellness League's Search Tool is a free resource that can be used to find clinical trials actively recruiting in your community. Simply search by a condition and then the type of study. Check out our blog on how to use the Tool. Scroll to the bottom of the page to watch our how-to video or download the printable guide.