Department of Epidemiology & Biostatistics, The University of Western Ontario, London, ON, Canada.
Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada.
Can J Anaesth. 2018 Jun;65(6):611-618. doi: 10.1007/s12630-018-1109-z. Epub 2018 Mar 22.
Although every randomized clinical trial (RCT) needs participants, determining the ideal number of participants that balances limited resources and the ability to detect a real effect is difficult. Focussing on two-arm, parallel group, superiority RCTs published in six general anesthesiology journals, the objective of this study was to compare the quality of sample size calculations for RCTs published in 2010 vs 2016.
Each RCT's full text was searched for the presence of a sample size calculation, and the assumptions made by the investigators were compared with the actual values observed in the results. Analyses were only performed for sample size calculations that were amenable to replication, defined as using a clearly identified outcome that was continuous or binary in a standard sample size calculation procedure.
The percentage of RCTs reporting all sample size calculation assumptions increased from 51% in 2010 to 84% in 2016. The difference between the values observed in the study and the expected values used for the sample size calculation for most RCTs was usually > 10% of the expected value, with negligible improvement from 2010 to 2016.
While the reporting of sample size calculations improved from 2010 to 2016, the expected values in these sample size calculations often assumed effect sizes larger than those actually observed in the study. Since overly optimistic assumptions may systematically lead to underpowered RCTs, improvements in how to calculate and report sample sizes in anesthesiology research are needed.
尽管每个随机对照试验（RCT）都需要参与者，但确定平衡有限资源和检测真实效果的理想参与者数量是困难的。本研究聚焦于在六本普通麻醉学期刊上发表的双臂、平行组、优效性 RCT，旨在比较 2010 年和 2016 年发表的 RCT 中样本量计算的质量。
对每个 RCT 的全文进行搜索，以确定是否存在样本量计算，并将研究者的假设与结果中观察到的实际值进行比较。仅对可复制的样本量计算进行分析，定义为使用明确识别的、在标准样本量计算程序中为连续或二分类的结局。
报告所有样本量计算假设的 RCT 的百分比从 2010 年的 51%增加到 2016 年的 84%。大多数 RCT 中，研究中观察到的值与用于样本量计算的预期值之间的差异通常>预期值的 10%，从 2010 年到 2016 年几乎没有改善。
虽然 2010 年至 2016 年样本量计算的报告有所改善，但这些样本量计算中的预期值通常假设的效应大小大于研究中实际观察到的效应大小。由于过于乐观的假设可能会导致 RCT 效能不足，因此需要改进麻醉学研究中样本量的计算和报告方法。
