Randomized controlled trials

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The randomized controlled trial (RCT) is generally referred to as the gold standard of research and is often used to compare interventions. It is basically an experimental trial comparing two or more groups who are randomly allocated to either one form of treatment or another. It is through this random allocation that the risk of extraneous variables is reduced, thus increasing the chance that any changes are caused only by the intervention, so allowing the cause and effect to be determined. The essential characteristics of this design include a hypothesis that one form of treatment or intervention will cause a particular effect (e.g. the nurse may develop a hypothesis that wound healing is improved with the use of a particular dressing and he or she may then aim to test this hypothesis). Second, the study is prospective in nature and patients are randomly allocated to receive either the intervention (i.e. the dressing to be tested) or the control (which in this case would be the accepted standard form of dressing). The researcher attempts to eradicate bias through the randomization process, thus comparing two groups who are very similar, apart from the variable under investigation (e.g. the dressing) (Figure 11.1).

Figure 11.1 Basic design structure for randomized controlled trials (RCTs).

As well as investigating the effects of certain types of interventions, drugs or procedures, the RCT is also useful in determining the most appropriate provision of care. RCTs are not appropriate for studies where there is difficulty in randomization, e.g. it would be unethical to randomize patients into certain arms of treatment where one particular treatment is known to have superiority. There are also some variations of RCT design, an example of which is the simple crossover method. This allows both groups to act as their own control by exposing them sequentially to both arms of the study. However, this would not be suitable for conditions that fluctuate before treatment, and also if there were residual effects of the first arm of the treatment causing potential bias (Bowling, 1997)

Example: RCT used in cancer care (Baildam et al., 2001)


To compare nurse-led versus doctor-led follow-up after a diagnosis of breast cancer and completion of treatment.


After a diagnosis of breast cancer, patients are generally followed up by their consultant or registrar for a period of 5-10 years. This randomized study compared follow-up by two specially trained experienced specialist nurses (experimental group) versus the traditional follow-up with doctors (control group).

Sample size

In total 525 patients were randomized to each of the groups. Outcome measures

This included differences in detection of recurrence between the two groups, recognition of patient psychological morbidity and patient satisfaction between the two groups. Psychological morbidity was measured using well-validated measurement tools to include the Hospital Anxiety and Depression Scale (HAD) and the Spiel-berger State Anxiety. Satisfaction was also measured using the Fallowfield Satisfaction with Consultation Questionnaire.


The results demonstrated that nurse recognition of psychological morbidity was greater than that recorded by the doctor. No differences in the ability to detect recurrence were found. The authors conclude that nurse-led clinics can provide high-quality care equal, at least, to that of their medical colleagues.

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