Observational Studies vs. Clinical Trials

What is the difference?

When we consider clinical trials, and try to understand each aspect and phase of these trials, we encourage reviewing the most well respected resources available which can be found  at www.clinicaltrials.gov or www.nia/nih.gov. These are  the FDA and NIH websites, respectively. Nearly all United States interventional trials must be cleared through the FDA for initiation. Some more simple research studies do not require governmental agency approval, especially if it involves an already approved FDA drug or compound, a questionnaire, or field testing various different endpoints or biomarkers.

Often researchers will perform different types of clinical studies and the National Institutes of Health (NIH) tries to separate this clinical research into 2 main categories

  • Observational Studies
  • Clinical Trials

Observational Studies: In many clinical studies the investigator (sometimes referred to as a researcher, or a primary investigator [PI]), does not do any experiments or test new treatments on the individual with the disorder they are investigating. Instead, they observe them or may do some standardized assessments. This observation or assessment helps the investigator understand the disorder, better describe the condition, and understand the most impacted areas of that condition (for example: communication abilities, sleep, motor function, fine motor function, seizures, tc..). Types of observational studies you might see include:

A detailed description of a single (or a few) patients. This is to document new and unusual cases.

Compares the rate or prevalence of a condition in a group of people, such as different geographic locations, different races, or different demographics.

An evaluation of many people at one moment in time. This can show how common a condition is, and maybe identify factors associated with the condition in a more general way.

Comparing a group of people with the condition to another group without the condition. This may identify risk factors or causes for the condition, or just identify strengths or weaknesses in a domain when compared to a different population.

A study where a large group of people are observed over a longer period of time. This can show the progression of the disorder, or the lack thereof. The Angelman Syndrome Natural History Study is this type of study.

Clinical Trials: In these types of studies, investigators test new ways to prevent, detect, or treat a disorder. Treatments might include investigating new drugs (novel or previously approved for other indications), a combination of drugs, new devices, or new approaches to use existing treatments. Clinical trials can also evaluate other aspects of patient care, like techniques to improve symptoms (e.g. specific speech therapy, physical therapy, or behavioral therapy approaches, tc..) or quality of life.

A well designed clinical trial is the gold-standard to prove that any treatment, or new medical approach, actually works.  Clinical trials are usually conducted in different phases. Depending on the disease, the known safety data of a drug or device, or the size of the population, some of these phases might be skipped or combined.

The purpose of a Phase 1 clinical trial is to find out if the new medical approach, drug, or device being tested is safe, well tolerated, to identify any potential side effects (adverse events), and to figure out the appropriate dose and dose frequency so that a larger study can be conducted to truly test the potential efficacy of the drug or device. This is often evaluated in a small number of patients (~20-100), depending on the size of the population and the different variables being tested.

The purpose of a Phase II clinical trial is to start testing whether a new medical approach, drug, or device, actually works to improve the symptoms or quality of life in this population. Side effects and tolerability continue to be carefully monitored, and all of this information goes into designing the larger Phase III clinical trial. This type of trial usually involves a larger number of individuals (~50-300), depending on the size of the population.

The purpose of a Phase III clinical trial is to try and prove whether a new medical approach, drug, or device works, while  continuing to monitor side effects.  The numbers of patients in these trials are usually larger, and this number is determined based on statistics from the useful endpoints evaluated in the Phase I/II trials. A large enough number of patients are needed to statistically show a meaningful change in the domains determined to be important in the disease, and impacted by the drug/intervention. For rare diseases this is often a few hundred (if possible) to even a few thousand individuals.

The purpose of a Phase IV clinical trial is for when a drug or intervention is being marketed to continue to gather information on its effects. Once the drug/device/therapeutic is approved by the FDA, the drug becomes available to the public and more monitoring is necessary to ensure safety in the general population is monitored for. Data about the benefits, best use, or issues related to the treatment are collected and analyzed by the research team

After a clinical trial ends, the researchers carefully review information collected during the study. These results drive the decision to continue or stop the clinical trial. For example, after a Phase I or Phase II study, the researchers may choose to stop the process because the new treatment was unsafe or did not help seem to show benefit to the patient. Alternatively, at this point the trial may move on to a Phase III clinical trial because results from the first two phases were showing some potential promise.

Once a new medical approach, drug, or device is proven safe and effective in a clinical trial, it may become a new standard of medical practice and approved by the regulatory agency to be widely available.


For more information about current clinical trials visit: www.clinicaltrials.gov or www.angelmanclinicaltrials.com

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