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Types of Clinical Trials

Clinical trials or clinical studies simply refer to those research studies that involve human volunteers and are conducted to add to our understanding of certain diseases. They are conducted only after the investigators have provided sufficient information to the health authorities involved in regulating these studies in that particular country which in the US, is the FDA and in Canada, is Health Canada.

There are two main types of clinical trials – observational and interventional. Observational trials are as the name suggests – researchers follow a group of volunteers, monitoring various aspects of their health. In Parkinson’s disease this type of data can allow for a deeper understanding of the disease, the factors that contribute to its development and the course of the disease for example, all of which help in developing new treatments.

Interventional trials are necessary when assessing the safety and efficacy of a new intervention. These interventions may include a new experimental drug or treatment, a medical device or procedure or may make a change in the person’s behavior (as in those trials that alter a person’s diet or exercise regimen). These interventional types of trials are conducted in phases.

  • Phase I trials test drugs of therapies for the first time in humans with its main goal being to establish safety as well as side effects and how the drug reacts in the human body. These trials are often quite small in terms of the number of people that they test and are most often conducted in healthy volunteers.

  • Phase II trials are larger trials, with many more participants (several hundred), that are used to further assess safety and effectiveness of the treatment being explored (usually against a placebo) in those that have the disease condition.

  • Phase III trials are larger still (several hundred to several thousand participants), usually conducted at multiple centers and gather further data on a therapy’s effectiveness, safety, side effect profile and compare it to the standard treatments already available.

  • Phase IV trials take place after a drug has been approved for use and looks at long-term side effects and effectiveness of the intervention with widespread use.

Within the whole broad spectrum of clinical trials (observational and interventional), there are other terms that may be used to classify the type of study being conducted.

Treatment trials refers to a study of a specific drug, therapy or intervention in relation to treating the disease condition.

Prevention trials are where the intervention is tested to see if it works in preventing the disease from developing or recurring.

Screening studies look at the best way to detect certain disease states. Genetics studies may be part of this process.

Quality of life studies look at ways to improve quality of life for those with chronic illness.

Regardless of the type of clinical trial, it is imperative for each stage or type of study to receive the support of volunteers. Because without enough participants, medical research to develop new treatments and ultimately a cure, cannot advance.

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