Akershus University College, P.O. Box 423, N-2001 Lillestrøm, Norway.
Nutr J. 2010 Dec 14;9:66. doi: 10.1186/1475-2891-9-66.
The ultrasonographic estimation of thyroid size has been advocated as being more precise than palpation to diagnose goitre. However, ultrasound also requires technical proficiency. This study was conducted among Saharawi refugees, where goitre is highly prevalent. The objectives were to assess the overall data quality of ultrasound measurements of thyroid volume (Tvol), including the intra- and inter-observer agreement, under field conditions, and to describe some of the practical challenges encountered.
In 2007 a cross-sectional study of 419 children (6-14 years old) and 405 women (15-45 years old) was performed on a population of Saharawi refugees with prevalent goitre, who reside in the Algerian desert. Tvol was measured by two trained fieldworkers using portable ultrasound equipment (examiner 1 measured 406 individuals, and examiner 2, 418 individuals). Intra- and inter-observer agreement was estimated in 12 children selected from the study population but not part of the main study. In the main study, an observer error was found in one examiner whose ultrasound images were corrected by linear regression after printing and remeasuring a sample of 272 images.
The intra-observer agreement in Tvol was higher in examiner 1, with an intraclass correlation coefficient (ICC) of 0.97 (95% CI: 0.91, 0.99) compared to 0.86 (95% CI: 0.60, 0.96) in examiner 2. The ICC for inter-observer agreement in Tvol was 0.38 (95% CI: -0.20, 0.77). Linear regression coefficients indicated a significant scaling bias in the original measurements of the AP and ML diameter and a systematic underestimation of Tvol (a product of AP, ML, CC and a constant). The agreement between re-measured and original Tvol measured by ICC (95% CI) was 0.76 (0.71, 0.81). The agreement between re-measured and corrected Tvol measured by ICC (95% CI) was 0.97 (0.96, 0.97).
An important challenge when using ultrasound to assess thyroid volume under field conditions is to recruit and train qualified personnel to perform the measurements. Methodological studies are important to assess data quality and can facilitate statistical corrections and improved estimates.
超声评估甲状腺大小被认为比触诊更精确，可以诊断甲状腺肿。然而，超声也需要技术熟练。本研究在甲状腺肿高发的撒哈拉难民中进行。目的是评估在现场条件下甲状腺体积（Tvol）超声测量的整体数据质量，包括观察者内和观察者间的一致性，并描述遇到的一些实际挑战。
2007 年，对居住在阿尔及利亚沙漠的撒哈拉难民中的甲状腺肿流行人群进行了一项横断面研究，共纳入 419 名 6-14 岁儿童和 405 名 15-45 岁女性。由两名经过培训的现场工作人员使用便携式超声设备（第一观察者测量了 406 人，第二观察者测量了 418 人）测量 Tvol。在从研究人群中选择的 12 名儿童中评估观察者内和观察者间的一致性，但这些儿童未参与主要研究。在主要研究中，发现一名观察者的超声图像存在观察者误差，通过线性回归对该观察者的 272 张图像进行了校正。
第一观察者的 Tvol 观察者内一致性较高，组内相关系数（ICC）为 0.97（95%置信区间：0.91，0.99），而第二观察者的 ICC 为 0.86（95%置信区间：0.60，0.96）。Tvol 观察者间一致性的 ICC 为 0.38（95%置信区间：-0.20，0.77）。线性回归系数表明，原始 AP 和 ML 直径的测量存在显著的缩放偏差，并且 Tvol 存在系统低估（AP、ML、CC 和常数的乘积）。根据 ICC（95%置信区间），重新测量和原始 Tvol 之间的一致性为 0.76（0.71，0.81）。根据 ICC（95%置信区间），重新测量和校正 Tvol 之间的一致性为 0.97（0.96，0.97）。
在现场条件下使用超声评估甲状腺体积时，一个重要的挑战是招募和培训合格的人员来进行测量。方法学研究对于评估数据质量很重要，并且可以促进统计校正和提高估计值。
