Objectives

The intra-class correlation coefficient (ICC) is a measure of intra-subject clustering effects. A priori estimates of the ICC and the associated design effect (DE) are required for sample size estimation in clustered studies, and should be considered during their analysis, too. We aimed to determine the clustering effects of carious lesions, apical lesions, periodontal bone loss, and periodontal pocketing, assessed in clinical or radiographic examinations.

Methods

A subsample of patients (n = 175) enrolled in the fifth German Oral Health Study provided data on clinically determined carious teeth (i.e., with untreated carious lesions, WHO method) as well as teeth with periodontal pocketing (i.e., with maximum probing-pocket-depths ≥ 4 mm). A sample of panoramic radiographs (n = 85) from randomly chosen patients, examined from 2010 to 2017 at the Charité dental hospital, provided data on radiographically determined carious teeth (i.e., with lesions extending into dentine or enamel), teeth with apical lesions (determined by dentists via majority vote), and teeth with periodontal bone loss (≥ 20% of root-length). The ICC and its 95% confidence interval (95% CI) were determined.

Results

There were 3839 and 1961 teeth assessed in clinical and radiographic evaluations, respectively. For clinically or radiographically determined carious lesions, the ICC (95% CI) was 0.20 (0.16–0.24) or 0.19 (0.14–0.25), respectively. For clinical pocketing or radiographic bone loss, the ICC was 0.40 (0.35–0.46) or 0.30 (0.24–0.38), respectively. The lowest ICC was found for apical lesions at 0.08 (0.06–0.13).

Conclusions

The ICC varied between assessment methods and conditions. Clustered trials should account for this during study planning and data analysis.

Clinical relevance

Within the limitations of this study, and considering the risk of selection bias and the limited sample sizes of both datasets, clustering effects were substantial but varied between dental conditions. Studies not accounting for this during planning and analysis may yield misleading estimates if clustering is present.

中文翻译：

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根据临床和影像学检查得出的口腔疾病的聚类效果。

目标

类内相关系数（ICC）是对象内聚类效果的量度。聚类研究中的样本量估计需要ICC的先验估计和相关的设计效果（DE），并且在分析时也应考虑这些估计。我们旨在确定在临床或X线检查中评估的龋齿病变，根尖病变，牙周骨丢失和牙周袋化的聚集效应。

方法

 参加德国第五次口腔健康研究的患者子样本（n = 175）提供了有关临床确定的龋齿（即，未经治疗的龋齿，WHO方法）以及牙周袋的牙齿（即，最大探查袋）的数据-深度≥4毫米）。 从2010年至2017年在Charité牙科医院检查的随机选择的患者的全景X射线照片（n = 85），提供了放射照相确定的龋齿（即，病变扩展到牙本质或牙釉质），尖顶病变的牙齿（由牙医通过多数表决确定），以及牙周骨缺损（≥牙根长度的20％）的牙齿。确定了ICC及其95％置信区间（95％CI）。

结果

临床和放射学评估分别评估了3839和1961颗牙齿。对于临床或放射学确定的龋齿病变，ICC（95％CI）分别为0.20（0.16-0.24）或0.19（0.14-0.25）。对于临床袋装或影像学上的骨丢失，ICC分别为0.40（0.35-0.46）或0.30（0.24-0.38）。发现根尖病变的最低ICC为0.08（0.06-0.13）。

结论

ICC在评估方法和条件之间有所不同。群集试验应在研究计划和数据分析过程中予以考虑。

临床相关性

在本研究的局限性内，考虑到选择偏倚的风险和两个数据集的样本量有限，聚类效果显着，但在不同的牙科条件下会有所不同。如果存在聚类，则在计划和分析过程中未考虑到这一点的研究可能会产生误导性的估计。