Clinical trials are the means by which therapeutic interventions are tested for their efficacy.
Types of clinical trialsEdit
There are three major types of clinical trials: placebo-controlled, open-label and observational clinical trials. Whenever "N" is given it refers to the number of participants.
Placebo-controlled trials are considered the gold-standard and highest quality of the three types of clinical trials. They are basically where patients are given either a placebo or the real drug. These trials are the gold-standard as they tell us whether or not any benefits purportedly caused by the drug was due to the drug or due to a placebo effect. It is worthwhile noting, that most placebo-controlled trials are also randomized and double-blind and these are really the ones that are considered the gold-standard studies (the abbreviation I will assign these trials is RDBPCTs). Randomization means that patients are randomly assigned either the placebo or the real drug. Double-blind means no one that comes into contact with the participant nor the participant know whether they are getting the active drug or a placebo.
The major problem with these trials is that sometimes the drug they are assigned produces such prominent, noticeable or otherwise obvious side effects like drowsiness that it is difficult to know for certain that the patients have been truly fooled into thinking they could have been randomized to receive a placebo.
Psychotherapy and exercise-based treatments are usually evaluated using randomized controlled trials as there is no convincing placebo that can be given, hence what they utilize to evaluate the efficacy of a treatment is they randomly assign them either no treatment or the treatment(s) being studied.
Open-label studies are basically what they sound like, the patient is given the drug and know what they are getting, there are no patients given a placebo. Open-label studies are considered the lowest-quality.
Observational studies, also known as cohort studies, are basically what they sound like, there is no process of randomization involved, no one is assigned a placebo, but rather what we do is we look at what happens to those given the drugs or whatever is being studied (like exercise) and compare their outcomes to (hopefully) well-matched members of the general population that are not taking the drug or whatever is being studied (like exercise, for example). Observational studies are tricky to assign a strength to their generalized quality, except to say they are inferior to the gold-standard RDBPCTs, but usually superior to open-label studies. The major reason why is that their quality really does depend on how well they were matched to those not taking the drug.