Arveschoug A K, Revsbech P, Brøchner-Mortensen J
Department of Clinical Physiology, Aalborg Hospital, Denmark.
Clin Physiol. 1998 Jul;18(4):361-8. doi: 10.1046/j.1365-2281.1998.00112.x.
Using the determination of distal blood pressure (DBP) measured using the strain gauge technique as an example of a routine clinical physiological investigation involving many different observers (laboratory technicians), the present study was carried out to assess (1) the influence of the number of observers and the number of analyses made by each observer on the precision of a definitive value; and (2) the minimal difference between two determinations to detect a real change. A total of 45 patients participated in the study. They were all referred for DBP determination on suspicion of arterial peripheral vascular disease. In 30 of the patients, the DBP curves were read twice, with a 5-week interval, by 10 laboratory technicians. The results were analysed using the variance component model. The remaining 15 patients had their DBP determined twice on two different days with an interval of 1-3 days and the total day-to-day variation (SDdiff) of DBP was determined. The inter- and intraobserver variations were, respectively, 5.7 and 4.9 mmHg at ankle level and 3.5 and 2.7 mmHg at toe level. The index values as related to systolic pressure were somewhat lower. The mean day-to-day variation was 11 mmHg at ankle level and 10 mmHg at toe level, thereby giving a minimal significant difference between two DBP determinations of 22 mmHg at ankle and 20 mmHg at toe level. To decrease the value of SD (standard deviation) on a definitive determination of DBP and index values, it was slightly more effective if the value was based on two observers performing one independent DBP curve reading than if one observer made one or two DBP curve readings. The reduction in SDdiff was greatest at ankle level. The extent of the Sddiff decrease was greatest when two different observers made a single DBP reading each at both determinations compared with one different observer making two readings at each determination. Surprisingly, about half of the maximum reduction in the SDdiff was achieved just by increasing the number of observers from one to two. We have found variance component analyses to be a suitable method for determining intra- and interobserver variation when several different observers take part in a routine laboratory investigation. It may be applied to other laboratory methods such as renography, isotope cardiography and myocardial perfusion single-photon emission computerized tomography (SPECT) scintigraphy, in which the final result may be affected by individual judgement during processing.
以使用应变计技术测量远端血压（DBP）作为一项涉及许多不同观察者（实验室技术人员）的常规临床生理研究为例，本研究旨在评估：（1）观察者数量以及每位观察者进行的分析次数对最终值精度的影响；（2）两次测定之间检测真实变化的最小差异。共有45名患者参与了该研究。他们均因疑似动脉外周血管疾病而被转诊进行DBP测定。其中30名患者的DBP曲线由10名实验室技术人员在间隔5周的时间内读取两次。结果采用方差成分模型进行分析。其余15名患者在间隔1 - 3天的两个不同日期进行了两次DBP测定，并确定了DBP的总体每日变化（SDdiff）。在脚踝水平，观察者间和观察者内的变化分别为5.7 mmHg和4.9 mmHg，在脚趾水平分别为3.5 mmHg和2.7 mmHg。与收缩压相关的指数值略低。脚踝水平的平均每日变化为11 mmHg，脚趾水平为10 mmHg，因此两次DBP测定之间的最小显著差异在脚踝处为22 mmHg，在脚趾处为20 mmHg。为了降低DBP和指数值最终测定的标准差（SD）值，基于两名观察者进行一次独立的DBP曲线读数所得到的值，比一名观察者进行一次或两次DBP曲线读数更为有效。SDdiff的降低在脚踝水平最为显著。与一名不同观察者在每次测定时进行两次读数相比，当两名不同观察者在每次测定时各自进行一次DBP读数时，SDdiff降低的程度最大。令人惊讶的是，仅将观察者数量从一名增加到两名，就实现了SDdiff最大降低幅度的约一半。我们发现，当有几名不同观察者参与常规实验室研究时，方差成分分析是确定观察者间和观察者内变化的合适方法。它可应用于其他实验室方法，如肾造影、同位素心动图和心肌灌注单光子发射计算机断层扫描（SPECT）闪烁扫描，在这些方法中，最终结果可能会受到处理过程中个人判断的影响。
