Julius Centre University of Malaya, Department of Social & Preventive Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Prev Med. 2013;57 Suppl:S80-2. doi: 10.1016/j.ypmed.2013.01.003. Epub 2013 Jan 11.
The Bland-Altman method is the most popular method used to assess the agreement of medical instruments. The main concern about this method is the presence of proportional bias. The slope of the regression line fitted to the Bland-Altman plot should be tested to exclude proportional bias. The aim of this study was to determine whether the overestimation of bias in the Bland-Altman analysis is still present even when the proportional bias has been excluded.
Data were collected from participants attending a workplace health screening program in a public university in Malaysia between 2009 and 2010. Variables collected were blood glucose level, body weight and systolic blood pressure (n=300 per variable). Readings from the original clinical dataset were compared with twenty randomly generated datasets for each variable. The Bland-Altman limits of agreement was used to determine the agreement. The presence of proportional bias was excluded for all datasets using the recommended method.
The range of predicted bias was higher than the simulated bias for all datasets. The overestimation of bias increased as the range of actual bias increased.
Testing the slope of regression line of the Bland-Altman plot does not remove the artifactual bias in the prediction.
Bland-Altman 法是评估医学仪器一致性最常用的方法。该方法的主要关注点是存在比例偏差。应测试拟合 Bland-Altman 图的回归线的斜率，以排除比例偏差。本研究旨在确定即使排除了比例偏差，Bland-Altman 分析中对偏差的高估是否仍然存在。
数据来自于 2009 年至 2010 年期间在马来西亚一所公立大学参加工作场所健康筛查计划的参与者。收集的变量包括血糖水平、体重和收缩压（每个变量 300 例）。将原始临床数据集的读数与每个变量的二十个随机生成数据集进行比较。使用 Bland-Altman 限来确定一致性。对于所有数据集，均使用推荐的方法排除比例偏差。
对于所有数据集，预测偏差的范围均高于模拟偏差。随着实际偏差范围的增加，偏差的高估程度增加。
测试 Bland-Altman 图回归线的斜率并不能消除预测中的人为偏差。
