cience is only as good as the evidence it is based upon. Since medical science has such a vital effect on our health it is important that every decision is based on strong clinical evidence. This evidence that is provided by clinical trials and research. The National Institutes of Health (NIH) describe clinical trials as “research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans” (1).
Clinical trials provide us with details about the effectiveness and safety of a clinical intervention. Many clinical trials help researchers come up with better treatment strategies for a certain disease, thus, some clinical trials compare the two treatment methods to find out which one is better and safer.
Clinical trials don’t study just the newest medications or interventions; they may be used to study the long-term effects of drugs and interventions that are already in common use. For example, recent clinical trials have found that hormonal therapy –which is already widely used- increases the risk of heart disease, stroke, blood clots and breast cancer. As a result, long-term use of hormonal therapy is no longer recommended in postmenopausal women (2).
Clinical trials are divided into phases. Each phase has different objectives and questions to answer. Scientists usually start a clinical trial on humans only after they have found a particular medication or intervention is effective in a laboratory or through animal studies. According to the FDA, clinical trials are carried out in four phases, with each phase building upon the knowledge gained from the prior phase (3). If the trial fails to fulfill its objective, it may be terminated (4).
Phase I Clinical Trial
Generally carried out in a very small group of people (usually 20-100 healthy subjects). The main objective of this trial is to understand safety, and safe dosages in humans.
Phase II Clinical Trial
In this phase, the trial is carried out on a larger group of people (several hundred people), and the objective is to know more about the effectiveness of medication or intervention, along with a collection of additional safety data.
Phase III Clinical Trial
Once the drug or intervention has been found safe and effective, it is tested on a much larger group of humans (usually few thousand) over the period of few years. If found effective and safe enough, it is given a marketing approval by FDA.
Phase IV Clinical Trial
The final phase, involving several thousand individuals suffering from the condition for which intervention or medication is being tested. Tests focus on the efficacy and safety on a much larger scale and in real life conditions.
It is also important to understand that not all clinical trials involve the study of new medications or interventions. For example, the genetic study of a group that suffers from a certain disease, or effect of living conditions on cardiac health.
Everyone has different reasons to participate in a clinical trial. Healthy subjects mostly participate because they think that it is their duty to help science in moving forward. Many people suffering from diseases may participate in the hopes of getting better or cured. There are many medical conditions for which there is currently no effective treatment, such as HIV, different kind of cancers, or even asthma.
There are certain eligibility criteria to decide who can participate in every clinical trial. Some trials require the participation of older people, while others focus on younger adults. Some may need healthy volunteers while others need patients with a particular disease condition. Trials may also vary in duration and location where they would be carried out. In some trials, a person may need to travel or stay at the medical facility.
Benefits depend upon the phase or type of clinical trial. Clinical trials provide a person early access to the latest developments in the field of medicine. A person also gets attention from the best specialists in their field, along with much better diagnostics. Apart from the possibility of direct health benefits, individuals get an opportunity to play a role in the development of science.
There is no guarantee that a person would benefit from any particular clinical trial. Some interventions or medications may cause unforeseen and severe side effects.
A person is informed about the possible risks when signing the informed consent. It is also important to know that informed consent is not a contract and a person can withdraw from the study at any given time.
Although fully understanding clinical trials can be difficult if you don’t have a background in science or healthcare, the official website of the US government for clinical trials has come up with a list of questions that may help a person to know more about clinical studies. Below is the list of questions you should ask before giving consent to participate (5);