Department of Orthodontics, School of Dentistry, University of Athens, Greece.
Eur J Orthod. 2012 Jun;34(3):287-92. doi: 10.1093/ejo/cjr122. Epub 2011 Oct 19.
In orthodontics, multiple site observations within patients or multiple observations collected at consecutive time points are often encountered. Clustered designs require larger sample sizes compared to individual randomized trials and special statistical analyses that account for the fact that observations within clusters are correlated. It is the purpose of this study to assess to what degree clustering effects are considered during design and data analysis in the three major orthodontic journals. The contents of the most recent 24 issues of the American Journal of Orthodontics and Dentofacial Orthopedics (AJODO), Angle Orthodontist (AO), and European Journal of Orthodontics (EJO) from December 2010 backwards were hand searched. Articles with clustering effects and whether the authors accounted for clustering effects were identified. Additionally, information was collected on: involvement of a statistician, single or multicenter study, number of authors in the publication, geographical area, and statistical significance. From the 1584 articles, after exclusions, 1062 were assessed for clustering effects from which 250 (23.5 per cent) were considered to have clustering effects in the design (kappa = 0.92, 95 per cent CI: 0.67-0.99 for inter rater agreement). From the studies with clustering effects only, 63 (25.20 per cent) had indicated accounting for clustering effects. There was evidence that the studies published in the AO have higher odds of accounting for clustering effects [AO versus AJODO: odds ratio (OR) = 2.17, 95 per cent confidence interval (CI): 1.06-4.43, P = 0.03; EJO versus AJODO: OR = 1.90, 95 per cent CI: 0.84-4.24, non-significant; and EJO versus AO: OR = 1.15, 95 per cent CI: 0.57-2.33, non-significant). The results of this study indicate that only about a quarter of the studies with clustering effects account for this in statistical data analysis.
在正畸学中，经常会遇到患者内的多个部位观察或连续时间点收集的多个观察结果。与个体随机试验相比，聚类设计需要更大的样本量，并且需要特殊的统计分析来考虑聚类内观察结果之间的相关性。本研究旨在评估在三大正畸期刊的设计和数据分析过程中，聚类效应被考虑到何种程度。从 2010 年 12 月开始，对《美国口腔正畸学和颌面正畸学杂志》（AJODO）、《Angle 正畸学》（AO）和《欧洲正畸学杂志》（EJO）最近的 24 期内容进行了手工搜索。确定了具有聚类效应的文章以及作者是否考虑了聚类效应。此外，还收集了以下信息：是否有统计学家参与、单中心或多中心研究、出版物中的作者人数、地理位置和统计学意义。在排除了 1584 篇文章后，对 1062 篇文章进行了聚类效应评估，其中 250 篇（23.5%）在设计中考虑了聚类效应（kappa = 0.92，95%置信区间：0.67-0.99，组内一致性）。在具有聚类效应的研究中，只有 63 篇（25.20%）表明考虑了聚类效应。有证据表明，在 AO 上发表的研究更有可能考虑聚类效应[AO 与 AJODO：比值比（OR）=2.17，95%置信区间（CI）：1.06-4.43，P=0.03；EJO 与 AJODO：OR=1.90，95%CI：0.84-4.24，非显著；EJO 与 AO：OR=1.15，95%CI：0.57-2.33，非显著]。本研究结果表明，只有约四分之一的具有聚类效应的研究在统计数据分析中考虑到了这一点。
