Clinical Sciences Building, University of Manchester, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Trust, Salford M6 8HD, UK.
Rheumatology (Oxford). 2012 Jul;51(7):1323-30. doi: 10.1093/rheumatology/kes007. Epub 2012 Mar 21.
Nailfold videocapillaroscopy is being increasingly used as a marker of SSc-related microvascular disease, including in response to treatment. However, it requires further validation. Our aim was to assess the inter-observer, intra-observer and test-retest variability of semi-automated measurement of capillary features as well as of a manual density measurement.
All capillary apexes in images from 58 patients with SSc were marked up independently by two trained observers (inter-observer variability). The first observer then re-marked the images (intra-observer variability), and finally, the first observer marked up a second image of the same nailfold (test-retest). Mark-up of capillaries was carried out on cropped mosaic images (cropped independently by the observers to a fixed width, to allow the same length of nail bed to be studied for each patient) and on whole mosaic images (examining the whole nail bed).
Reproducibility of independently cropped mosaic images was poor and was due to the variation in the positioning of the cropped area. However, quantification of whole mosaic images was highly reproducible, e.g. for inter-capillary distance, the intra-class correlation coefficient for inter-observer, intra-observer and test-retest reliability was 0.95, 0.98 and 0.90 (compared with 0.88, 0.79 and 0.89 for cropped mosaic images), respectively. Intra-observer limits of agreement for whole mosaic images were better than inter-observer reproducibility.
Quantitative assessment of SSc-related change in nailfold capillaries is unreliable if examination of the same set of capillaries cannot be guaranteed. Conversely a wide-field, high-magnification system that allows visualization of the whole nail bed offers a highly reproducible approach for quantitative assessment and therefore has potential as an outcome measure.
甲襞毛细血管显微镜检查法作为 SSc 相关微血管疾病的标志物（包括治疗反应）的应用日益增多，但需要进一步验证。我们的目的是评估半自动化测量毛细血管特征以及手动密度测量的观察者间、观察者内和复测间的可变性。
58 例 SSc 患者的图像中所有毛细血管顶点均由两位训练有素的观察者独立标记（观察者间可变性）。第一位观察者随后重新标记图像（观察者内可变性），最后，第一位观察者标记同一块甲襞的第二张图像（复测）。对裁剪马赛克图像（观察者独立裁剪到固定宽度，以便为每位患者研究相同长度的甲床）和全马赛克图像（检查整个甲床）进行毛细血管标记。
独立裁剪马赛克图像的可重复性差，这是由于裁剪区域的位置变化所致。然而，全马赛克图像的定量评估具有高度可重复性，例如，对于毛细血管间距离，观察者间、观察者内和复测的组内相关系数分别为 0.95、0.98 和 0.90（相比之下，裁剪马赛克图像的组内相关系数分别为 0.88、0.79 和 0.89）。全马赛克图像的观察者内一致性界限优于观察者间可重复性。
如果不能保证检查同一组毛细血管，定量评估 SSc 相关的甲襞毛细血管变化是不可靠的。相反，能够可视化整个甲床的宽视场、高倍放大系统为定量评估提供了一种高度可重复的方法，因此具有作为结局测量的潜力。
