- Manuela L Ferreira, research fellow1,
- Robert D Herbert, professor2,
- Michael J Crowther, research associate3,
- Arianne Verhagen, associate professor4,
- Alex J Sutton, professor of medical statistics3
- 1The George Institute for Global Health, University of Sydney, PO Box M201, Missenden Road, NSW 2050, Australia
- 2Neuroscience Research Australia, Sydney, Australia
- 3Department of Health Sciences, University of Leicester, UK
- 4Department of General Practice, Erasmus Medical Centre University, Rotterdam, Netherlands
- Correspondence to: M L Ferreira
- Accepted 21 August 2012
Even on their own the best randomised trials do not usually provide convincing evidence of the effectiveness (or lack of effectiveness) of an intervention. Consensus about effectiveness is usually only achieved when a meta-analysis of several high quality trials shows a statistically significant effect. Until such a consensus is achieved researchers may claim that a new trial is justified. We will refer to this as the “conventional approach” to justification of a new trial.
Two problems, and solutions
There are two problems with the conventional approach. The first concerns the interpretation of existing evidence: interpretation of data from clinical trials or meta-analyses is reduced to a decision about whether the intervention is “effective” or “ineffective.”1 The simplistic classification of interventions as effective or ineffective fails to make the important distinction between interventions that have trivial effects and those that have worthwhile effects.
A health intervention produces “worthwhile” effects when it does more good than harm. Here we must use the term “harm” to include all of the negative aspects of interventions: from a patient’s perspective, these could include risks of adverse events, pain or discomfort, cost, or inconvenience. The role of clinical trials is to provide unbiased estimates of the beneficial effects of health interventions so that it can be ascertained whether those effects outweigh risks, costs, and inconvenience.
Several methods have been developed to determine what beneficial effect would outweigh the risks, costs, and inconvenience of an …