This is a trial in which:
1) There are two groups, one treatment group and one control group. The treatment group receives the treatment under investigation, and the control group receives either no treatment (placebo) or standard treatment.
2) Patients are randomly assigned to all groups.
A type of randomized controlled clinical trial/study in which neither medical staff/physician nor the patient knows which of several possible treatments/therapies the patient is receiving.
Similar to RCTs, except that subjects are not randomly assigned to the treatment or control groups. This increases the chance for “bias”–that is, that people with similar qualities ended up in each of the groups which could influence the final results.
Consist of collections of reports on the treatment of individual patients or a report on a single patient. Because they are reports of cases and use no control groups to compare outcomes, they have little statistical validity.
Patients who already have a certain condition are compared with people who do not.
Identify a group of patients who are already taking a particular treatment or have an exposure, follow them forward over time, and then compare their outcomes with a similar group that has not been affected by the treatment or exposure being studied. Cohort studies are observational and not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study.