Clinical Trials: How Do They Work?

A clinical trial is a type of medical research that measures the success of newly available prevention, detection, or treatment options for illness or disease.

Clinical trials evaluate the safety and efficacy of things like:

• New drugs, vaccines, medical devices, or surgical methods

• Combining existing interventions

• Applying medical interventions in new ways (such as treating diseases they weren't originally intended to treat)

Although they're just one part of a larger research life cycle, clinical trials play a critical role in making interventions available to the public. The clinical trial phase is when interventions are put to the test in the human body for the first time.

Why are clinical trials necessary?

Before an intervention is eligible for a clinical trial, researchers must prove that it's likely safe and effective in humans. They do this through a string of pre-clinical studies that test the approach— first against lab-grown cells and then with live animals.

The pre-clinical phase can shed light on whether an intervention will serve its intended purpose. Still, these studies cannot detect all outcomes or side effects, which means that human research is vital.

In a clinical trial, researchers recruit human volunteers to enroll in studies that help test their hypothesis about a given intervention. Without these participants, it would be impossible to know what to expect when bringing a new drug, device, or treatment method to market.

Also, by studying the effects of an intervention on a carefully selected participant pool, researchers can evaluate the change in outcomes relative to similar interventions or with no intervention at all (the placebo effect).

What are the four types of clinical trials?

Clinical trials are designed in several ways. The most common types of clinical trials include:

1. Prevention trials that aim to identify methods to reduce the incidence of a particular disease. They study the impacts of lifestyle changes or medications/supplements on healthy individuals at high risk of developing a particular disease.  

2. Screening trials that look for new or better ways to identify disease or illness in the population. 

3. Diagnostic trials that seek to create more accurate ways to test for and diagnose disease.

4. Treatment trials measure a specific treatment’s ability to improve the outcome for a participant diagnosed with a particular disease.

While each type of clinical trial serves a slightly different purpose, all clinical trials must pass through a series of phases before an intervention gets approved for general use.

What are the phases of clinical trials?

Clinical trial phases exist to ensure that researchers can answer essential questions about the safety and efficacy of intervention while keeping human participants safe.

Depending on the type of intervention tested, most clinical trials are subject to four phases over approximately six to seven years. Each phase serves a specific purpose.

Phase I (Safety)

Researchers attempt to confirm the safety of the intervention in humans. They do this by administering the intervention to a small number of study participants monitored closely for potential side effects.

This research phase poses the most significant risk to participant health, and the results from phase I must be approved by the FDA before research can advance to phase II.

In cases where an intervention is proven effective for the treatment or prevention of another disease, it's possible for researchers to accelerate or skip phase I based on the existing safety profile.

Phase II (Effectiveness)

Researchers monitor the effectiveness of the intervention. The intervention now gets administered to a larger group of study participants. Researchers then watch for signs that it's having the intended effect and work to identify the appropriate form, dosage, and more, in preparation for the later phases of the trial.

Phase III (Comparison)

Researchers seek to prove the intervention is an improvement on existing options. After the intervention has been proven safe and effective, researchers begin comparing it to available alternatives by performing a double-blind study—a study in which neither the participants nor researchers know whether the intervention or placebo has been given.

If the new intervention is proven safer or more effective than others on the market, it can be submitted to the FDA for approval after this phase. The intervention can also progress if it is equivalent to what is currently available.

Phase IV (Post-Market)

Researchers monitor the intervention long-term. Interventions enter phase IV clinical trials after being approved by the FDA. In this phase, research is conducted to understand the long-term effects of the intervention, its cost-effectiveness, and more.

Phase IV is the safest clinical trial phase for participants and may last as long as ten years.

Though uncommon, some drug trials will also include phase 0. This small study usually incorporates no more than 15 participants and seeks to determine whether the drug has the intended effect on the disease before launching a full clinical trial.

The lowdown

Clinical trials are critical to developing new and better prevention, detection, and treatment options for chronic disease and illness. With various trial formats and a series of phases designed to keep participants safe, clinical trials can be a great way to improve your health and help the community.

Easily find and apply for a clinical trial with HealthMatch

Whether you're looking for relief from a medical concern or hoping to help others, HealthMatch makes it easy for you to find clinical trials that are right for you.

Simply search for a condition and fill out a few health and demographic details, and we'll match you up with any trials you're eligible for. From there, apply to as many trials as you'd like with a single click.

Get started here.