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What is a Clinical Trial?

Much of the information on our website is supported by references to studies and clinical trials.  It’s important to understand what this means, so we’ve included some definitions, below.


Surveys are used to assess attitudes and opinions, and to gather information as part of Clinical Studies.

The ED Treatment Information Center conducts surveys to assess the emotional impact of erectile dysfunction, and attitudes toward various treatment options.

Clinical Studies

A clinical study gathers information by observing people over time, or by asking them questions.  For example, a study may ask men about their lifestyle and environment, and then assess their erectile dysfunction, to determine the effects of lifestyle factors on ED.  A clinical study does not involve actually treating the patient.

Clinical studies are also called observational studies.

Clinical Trials

Clinical trials are used to assess medical treatments.  Trials determine the safety and effectiveness of these treatments.

The treatment is administered to patients, and the effects are recorded. In many cases, a second group of patients who are not given the treatment will be compared to the patients receiving treatment. This second group may be given a placebo (a fake treatment), so that none of the patients know if they are actually being given the treatment.

Data gathered in clinical trials is made available (often through publication in medical journals) for peer review.

Before trials begin on humans, researchers often test the treatments on animals; the results of these animal studies may also be reported, as an early indication of the safety and effectiveness of the treatment.

Human trials must be approved by an Institution Review Board (IRB), which is required to protect the rights and welfare of the subjects.

There are four phases of clinical trials on humans:

Phase 1 tests the treatment on a small number of patients (20-80).  The primary purpose of a Phase 1 trial is to judge the safety of the treatment, before starting larger trials.  The effectiveness may also be reported, but results from a Phase 1 trial are considered very preliminary.

Phase 2 focusses on effectiveness (although safety, including side effects, is still monitored).  A Phase 2 study may last several years, and involves 100-300 people.

Phase 3 gathers more information about safety and effectiveness.  The treatment will be tested on different groups of people; dosages and other details of the treatment may be varied to determine the optimum treatment.  Phase 3 trials involve several hundred to several thousand patients.  If the Phase 3 trial is successful, the FDA may approve the treatment for general use.  Note that the FDA does not regulate all treatments.  In general, the FDA regulates drugs, medical devices, and surgical procedures.  It does not regulate treatments that don’t fall into these categories, such as massage techniques or diet programs.

Phase 4 trials continue after the treatment is approved.  The goal is to assess long-term impact over large, diverse groups of patients.  The FDA will often require Phase 4 trials as a condition for approving the treatment.

How Are Treatments Approved?

In the United States, a federal agency called the Food and Drug Administration (FDA) is responsible for the decision to approve a drug or treatment, based on the evidence provided by clinical trials. Similar agencies exist in most countries; poorer countries may base their decisions on the decisions made by countries with more resources.

The decision to approve a treatment requires balancing risks and benefits.

For example, a treatment with high risks may be approved if it has significant benefits over existing treatments.

On the other hand, a treatment with moderate risks may be rejected if there are already equally effective treatments on the market.

It’s a difficult role, because the FDA is blamed if they keep treatments from the market, but they are also blamed if they approve treatments that cause serious harm.

Who Conducts and Funds Clinical Trials?

Clinical studies and trials are conducted by research teams consisting of doctors and other health professionals, as well as researchers specializing in data science and statistical analysis.  They may take place in hospitals, universities, clinics, or private laboratories.

Studies and trials are funded by universities, hospitals, private foundations, pharmaceutical companies, medical device manufacturers,  Federal agencies (such as the National Institutes of Health), the U.S. Department of Defense, and the U.S. Department of Veterans Affairs.  Small studies may even be funded by doctors, medical groups, or researchers.

Pre-Approval for Studies and Trials

In most cases, clinical studies, trials, and even surveys must be approved by an Institutional Review Board (IRB) before they are started.  The primary role of the IRB is to protect the rights and welfare of the human subjects.

In general, an IRB review is required if:

  • The study is to be submitted to the US Federal Drug Administration or Department of Health and Human Services, or
  • The study receives federal funding.

Most universities and independent hospitals also require an IRS review for any studies done there.

Can Clinical Trials be Trusted?

Some people believe that clinical trials can’t be trusted because they are “funded by pharmaceutical companies.”  They assume that the results must be biased toward the drugs and treatments being tested.

It’s important to remember that:

  • Funding for trials comes from many sources.
  • An Institutional Review Board must approve the study.
  • The FDA closely monitors all clinical trials.
  • When studies are submitted for publication, they are reviewed by other scientists and researchers not associated with the study.  Most prominent medical journals have screening processes to ensure the scientific validity of studies that they publish.
  • The data from the trials must be made available for other researchers to analyze.
  • Doctors and researchers who run trials are staking their reputations and careers on the integrity of the trials.

Most clinical trials yield negative results, which would certainly not be the case if the results were dictated by the funding companies.

There have certainly been incidents of fraud found in clinical trials.  Also, not all clinical trials are well run…  simply put, some researchers are more skilled than others.  But for the most part the system works well to insure the validity of clinical research.

What Do Clinical Trials Tell Us?

Given all the emphasis on testing, it’s surprising that FDA drug approval is just the start of the process.  There is always a tradeoff between getting new treatments into use, versus protecting against all risks.

FDA approval, following successful clinical trials, tells us that:

  • The treatment delivers measurable benefits.
  • The major risks of the treatment are known.
  • The benefits are judged to outweigh the risks.

The trials usually do not tell us that:

  • The treatment is risk-free.
  • There are no long-term side effects.
  • The treatment does not have dangerous interactions with other drugs or treatments.
  • The treatment will not have negative side-effects for people with specific pre-existing conditions.

That’s why Phase 4 clinical trials continue even after a treatment is approved for use.

At the bottom of many of our articles and posts, you will see References to clinical studies and trials that support the information that we publish.

We are sometimes harshly critical of groups that make claims for treatments without any clinical research. In our opinion, these groups are, at best, taking advantage of people, and at worst, putting their health at risk.