RANDOMIZED CONTROLLED TRIAL

Randomized Controlled Trial

Randomized Controlled Trial

Randomized Controlled Trial

An experiment to measure the efficacy (the extent to which it has a therapeutic effect under experimentally controlled conditions), effectiveness (the extent to which it has a therapeutic effect in real-world conditions) and cost-effectiveness (the extent to which it can be judged value for money when compared with alternatives) of an intervention. RCTs are most often used to evaluate treatments for physical or psychiatric disorders, but have also been used to investigate the effects of educational interventions and even agricultural methods.

Patients are randomly allocated to several alternative conditions or treatment arms, typically an experimental treatment, a placebo treatment and/or an already established treatment. (A placebo control treatment may be unethical if the disorder of interest is life-threatening or if an established treatment is known to be effective.) (Ajetunmobi O, pp.34-67, 2002). Attempts are made to control any sources of bias (see s. 8) that might affect the interpretation of the results. In double-blind trials, both the patient and the researcher measuring the patient's therapeutic response are kept ignorant of which treatment the patient has received; in this way patients' and clinicians' expectations cannot affect the outcome. However, a double-blind design is usually impossible in the case of psychological treatments. In these circumstances, a single-blind design may be employed, in which only the researcher measuring the therapeutic response is kept ignorant of the treatment assignment. Open trials, in which all participants are aware of treatment allocation, are not to be trusted as they nearly always lead to inflated estimates of a treatment's effect.

An intention to treat analysis of RCT data (in which data from all those entering the study are included) is usually preferred over per-protocol analysis (in which only data from those successfully completing treatment are considered) (Robson C, pp.56-89, 2002).

Health care costs place a considerable burden on modern societies - 14.6 per cent and 7.7 per cent of gross domestic product in the USA and UK respectively in 2002, according to the Organization for Economic CoOperation and Development. Moreover, the need for health care is almost limitless, because of the increasing range of conditions deemed worthy of treatment and because of the spiralling cost of new health care technologies. For these reasons, health care providers (the National Health Service in the UK, insurance companies in the USA) rely on RCTs to determine the most cost-effective interventions. However, some critics have pointed out that RCTs are not always practical or ethical (Bowling A, pp.89-98, 2009) and that alternative methods, including simple observation, can often yield useful data about treatment effects. Single case studies and multiple baseline experiments can yield valuable information about efficacy, and these kinds of studies are often carried out before investing the considerable sums needed to carry out an RCT (Sim J, Wright C, 34-67, 2000).

In recent years, the statistical method of meta-analysis has been used to combine data from a number of RCTs to provide an overall verdict on the value of different types of ...