Department of Orthodontics and Dentofacial Orthopedics, Dental School/Medical Faculty, University of Bern, Bern, Switzerland.
Am J Orthod Dentofacial Orthop. 2011 Oct;140(4):e141-6. doi: 10.1016/j.ajodo.2011.04.021.
Proper sample size estimation is an important part of clinical trial methodology and closely related to the precision and power of the trial's results. Trials with sufficient sample sizes are scientifically and ethically justified and more credible compared with trials with insufficient sizes. Planning clinical trials with inadequate sample sizes might be considered as a waste of time and resources, as well as unethical, since patients might be enrolled in a study in which the expected results will not be trusted and are unlikely to have an impact on clinical practice. Because of the low emphasis of sample size calculation in clinical trials in orthodontics, it is the objective of this article to introduce the orthodontic clinician to the importance and the general principles of sample size calculations for randomized controlled trials to serve as guidance for study designs and as a tool for quality assessment when reviewing published clinical trials in our specialty. Examples of calculations are shown for 2-arm parallel trials applicable to orthodontics. The working examples are analyzed, and the implications of design or inherent complexities in each category are discussed.
正确的样本量估计是临床试验方法学的重要组成部分，与试验结果的精确性和功效密切相关。与样本量不足的试验相比，样本量充足的试验在科学和伦理上是合理的，并且更具可信度。计划样本量不足的临床试验可能被认为是浪费时间和资源，也是不道德的，因为患者可能会被纳入一项研究中，而该研究的预期结果将不可信，并且不太可能对临床实践产生影响。由于正畸学临床试验中对样本量计算的重视程度较低，本文的目的是向正畸临床医生介绍随机对照试验中样本量计算的重要性和一般原则，为研究设计提供指导，并在审查我们专业领域的已发表临床试验时作为质量评估工具。展示了适用于正畸学的 2 臂平行试验的计算示例。对工作示例进行了分析，并讨论了每个类别中的设计或固有复杂性的影响。
