When studying about the clinical trials, we are in a position to understand that the clinical trials are classified in various ways apart from just the trial phase alone. Hence, a particular type of clinical trial will also depend upon the criteria of classification. Here, is the short view about the various types of clinical trials for you.
Therapeutic or Non-Therapeutic Clinical Trials:
Based on this criterion, the clinical trials can be classified into two types:
Therapeutic Trial: This is a clinical trial in which the investigational treatment is expected to benefit the trial subjects in some way. In case of the studies that involve of drug administration, the participants who receive the experimental drug are expected to get benefited.
Non-Therapeutic Trial: This is a type of study which is unlikely to provide any direct benefit to the included trial subjects. In most of the cases, the main aim of this type of clinical trial would be to gain knowledge which might towards the prospective development of novel treatment and/or procedure. (1)
Based On the Primary Objective of Clinical Trial:
Based on the primary objective, the clinical trials can be classified as follows:
Interventional Trial: This can also be called as a treatment trial and is set out for testing the treatment or combination of treatments that are not yet been approved. In these types of clinical trials, some drugs might be aimed either at curing or controlling the symptoms of a particular medical condition.
Prevention Trial: This type of clinical trial would aim at testing new approaches that are believed to lower the risks of developing certain diseases. At times, the aim would be to prevent the condition from recurring also. Most of the times, these studies will be conducted in healthy volunteers. Most typically, the prevention trials would emphasize on the following:
o Lifestyle changes
o Other supplements
Screening Trial: This type of trial would test the new approaches for finding the disease earlier. When a particular medical condition is found earlier, it would be easier to treat. This way, there will be higher chances for long-term survival. More usually, the screening trials would include people who are not having the signs and symptoms of the particular medical condition. Examples of screening trial include the studying of:
o Medical Imaging Methods
o Laboratory Tests
o Genetic Tests
Diagnostic Trial: This kind of clinical trial would aim at studying new tests and procedures that might help in identifying or diagnosing the particular medical condition more accurately. In contrast to the screening trial, these trials would include the people who are carrying some signs and symptoms of the disease under study.
Quality of Life Trial: This trial can also be called as 'Supportive Care' study or 'Palliative Care' study. These trials would look at the ways for improving the quality of life of the patients. They would aim at finding the ways to help patients in coping with:
o Nutrition problems
o Sleep disorders
o Other health issues (1), (2), (3), (4), (5)
Based On the Study Design of Clinical Trial:
Based on the study design, the clinical trials are classified as follows:
Observational Trial: These trials would investigate the health issues in larger groups of study population. In this trial type, the study subjects will not receive any treatment. However, they may be asked to provide data and blood samples. This can be called as 'Analytical Epidemiological' trial. The sub-types are:
o Observational descriptive trial
o Observational analytical trial
Open-label Trial: In this study, both the trial participant as well as the researcher will be well aware of the drug being administered. This can also be called as 'Non-Blinded' trial.
Blinded Trial: These clinical trials can be sub-divided as:
o Single-Blind Trial: In this clinical trial, the trial subjects will not know which group they are assigned to. They are blinded from the intervention being given.
o Double-Blind Trial: In these clinical trials, both the subject and the researcher will not know about the intervention being provided.
o Triple-Blind Trial: This is a trial in which the participant, observer-researcher and analyzing researcher do not know about the intervention being given to the subject.
Crossover Trial: This is a longitudinal trial in which the study subjects would receive a sequence of different interventions.(1), (10), (6)
Based on Enrollment of Subjects into Clinical Trial:
There are two basic types of clinical trials based on when and how the participants are enrolled into the trial. They are:
Prospective Trial: This is a trial which would look for the study outcomes during the study period. The study subjects will be followed into the future for the purpose of recording the development of the outcome of interest.
Retrospective Trial: This study would look backward for examining the exposures to suspected risks. The incidences of disease will be compared. In this trial, the exposure status as well as the outcomes will be ascertained in a retrospective manner. (10), (7), (8)
Based on the Number of Centers:
There are two types of clinical trials based on the number of centers in which the particular trial is being conducted which are:
Unicenter Trial: This is also known as 'monocenter' trial. This is a trial which will be conducted at only one location (hospital, university and so on).
Multicenter Trial: This is a clinical trial which will be conducted in more than one location. The different locations may include different cities and even countries. The multicenter trial has various advantages like:
o Large number of trial subjects
o Varying geographical locations
o Wide range of population groups
o Ability to compare the results obtained (10), (9), (1)
Thus, these are the general ways in which a clinical trial is being classified. In addition to the aforementioned types of clinical trials, there are also some other types like explanatory, parallel, sequential, pilot and so on depending on interventions and size. Knowing these will also be helpful in getting a better understanding about the clinical trials.