To the Editor.
I read the paper from Zhihui Fu et al. published in J Cardiothorac Surg [
1]. The aim of the study was to assess the diagnostic value of D-dimer with simplified Geneva score (SGS) pre-test in the diagnosis of pulmonary embolism (PE). In a retrospective analysis, 1035 patients with suspected PE were recruited. All enrolled patients were grouped according to the computed tomographic pulmonary angiogram (CTPA) results: PE patients and non-PE patients. Then, receiver operating characteristic (ROC) curve were constructed to determine the optimal D-dimer cutoff point value which is based on Yonden’s index (YI).
Although I appreciate this significant study, I would like to raise some methodological issues that can affect the interpretation of results. First, any decision in clinical practice needs to evaluate both reliability (precision) and validity (accuracy) of CTPA. Without knowledge about the reliability, any judgment would be wrong [
2‐
6]. Second, in diagnostic accuracy research, it is essential to evaluate the diagnostic added value of CTPA, since a diagnostic accuracy of a single test might be excellent, however for clinical purposes it can be worthless. Like evaluating discrimination, it would be possible to estimate the diagnostic added value by applying ROC of diagnostic model with and without CTPA [
2,
7,
8]. Hence, we suggest the authors to estimate both diagnostic added value and reliability of the CTPA by an appropriate method.
Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit
http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (
http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.