Randomised controlled trials and changing public health practice

Anne Cockcroft

One reason for doing randomised controlled trials (RCTs) is that experiments can be convincing. Early epidemiological experimenters, such as Jenner and the smallpox vaccine and Snow and his famous Broad Street pump handle, already knew the answer they were demonstrating; they used the experiments as knowledge translation devices to convince others.More sophisticated modern experiments include cluster randomised controlled trials (CRCTs) for experiments in the public health setting. The knowledge translation value remains: RCTs and CRCTs can potentially stimulate changes of practice among stakeholders. Capitalising on the knowledge translation value of RCTs requires more than the standard reporting of trials. Those who are convinced by a trial and want to act, need to know how the trial relates to their own context, what contributed to success, and what might make it even more effective. Implementation research unpacks the back-story, examining how and why an intervention worked.The Camino Verde trial of community mobilisation for control of dengue reported a significant impact on entomological indices of the Aedes aegypti vector, and on serological dengue virus infection and self-reported dengue cases. This important study should lead to studies of similar interventions in other contexts, and ultimately to changes in dengue control practices. This supplement is the back-story of the trial, providing information to help researchers and planners to make use of the trial findings.Background articles include the full protocol, a systematic review of CRCTs of approaches for Aedes aegypti control, epidemiological and entomological findings from the baseline survey, and how baseline findings were used to set up the intervention. Secondary analyses of the entomological findings examine associations with the use of the larvicide temephos, and the impact of the intervention in different conditions of water supply and seasons.Other articles describe implementation and other impacts: the underlying approach; implementation in the trial's different social contexts; the different impact in women and men; the effects of using fish for vector control; the impact on household costs of personal protection and of cases of dengue illness; and ethical issues.We hope this supplement will increase the knowledge translation value of the Camino Verde trial.