Assessing methods to specify the targeted difference for a randomised controlled trial

越来越多的人认识到，关于提供什么医疗保健的决定应该以证据为基础。需要的证据之一是，这种干预是否有益和值得使用可用于提供医疗保健的有限资金。可以说，提供这一证据的最佳方式是进行随机对照试验。在随机对照试验中，个体或个体组通常被随机分配接受新的治疗(这可能是提供护理的方式)或替代治疗。需要足够数量的人，这样我们才能确信，如果治疗方法之间存在差异，我们就能发现它。希望确定的两种治疗之间的差异大小(目标差异)影响需要招募的人数和研究的成本。如果没有正确识别目标差异，那么时间、努力(患者、卫生保健从业者和研究人员)和金钱可能会被浪费或使用不当。还有一种可能是，患者的健康可能会受到不利影响，因为目标差异太小，我们继续随机对患者进行治疗，我们本应能够说治疗效果较差。或者，如果靶点太大，我们可能无法检测到真正重要的差异，从而推迟或阻止有价值的治疗的引入。在这项研究中，我们将系统地确定确定靶点差异的方法。将确定描述不同方法的科学论文，将联系该领域的专家，我们将调查积极参与随机控制瓷砖设计和实施的组织和个人。我们将描述我们确定的不同方法，评估其优点和缺点，并评估其潜在的使用范围。我们将为随机临床试验的研究人员和资助者制定指南草案。这将包括不同类型试验的单独章节，以及衡量治疗结果的不同方式。该指导意见将首先在研究申请者和一个专家咨询小组之间进行讨论。然后，这些建议将在一个专题讨论会上提出，对设计和进行试验感兴趣的人将参加，这将有助于进一步完善建议，并作为传播的第一种方法。

Increasingly it is acknowledged that decisions about what health care to provide should be evidence based. One part of the evidence needed is whether the intervention is a beneficial and worthwhile use of the limited money available to provide health care. Arguably the best way of providing this evidence is by conducting a randomised controlled trial. In a randomised controlled trial individuals, or groups of individuals, are typically randomly assigned to receive either the new treatment (which might be the way in which care is provided) or an alternative treatment. A sufficient number of people is needed so that we can be confident that if a difference between treatments exists we can detect it. The size of difference between the two treatments desired to be identified (the target difference) affects the number of people needed to be recruited and the cost of the study. If the target difference is not correctly identified then there is a chance that time, effort (by patients, health care practitioners and researchers) and money will be wasted or poorly used. It is also possible that the health of patients may be adverse affected because the target difference was too small and we carry on randomising people to a treatment that we should already be able to say is inferior. Alternatively, if the target is too large we may fail to detect a truly important difference and as a result delay or prevent the introduction of a worthwhile treatment.In this study we will systematically identify methods of determining the target difference. Scientific papers will be identified that described different methods, experts in the field will be approached, and we will survey organisations and individuals who are actively involved in the design and conduct of randomised controlled tiles. The different methods that we identify will be described, strengths and weaknesses appraised and potential scope for their use assessed. We will develop draft guidance for researchers and funders of randomised clinical trials. This will include separate sections for different types of trials and on different ways in which the outcomes of a treatment might be measured. This guidance will first be discussed amongst the study applicants and an expert advisory group. The recommendations will then presented at a symposium to which those with an interest in the design and conduct of trials and will help further refine recommendations and act as a first method of dissemination.