ABSTRACT
Randomized controlled trials are considered the ‘gold standard’ of clinical and epidemiological studies. They are intervention studies that choose a group of patients who are suitable for one or more types of drug or intervention (e.g. surgery). If one treatment is being tested then it can be compared with either placebo or the existing gold standard. Further comparisons may be made between treatments or population subtypes by addition of ‘arms’ to the trial. Additionally, more than one treatment or combinations of treatments could be compared directly to placebo. A conclusion drawn from a carefully conducted randomized controlled trial that is of adequate size and has used techniques such as double blinding or placebo treatments is considered the most reliable, sometimes referred to as ‘top level’ or ‘level 1’, evidence as to whether a treatment is effective or not.
