YEARS Algorithm Versus Wells' Score: Incomplete Reporting Undermines Study Quality Assessment.

To the Editor: We read with interest the recent study by Abdelaal Ahmed Mahmoud M Alkhatip et al (1), published in the recent issue of Critical Care Medicine, in which they selected data from 794 patients who had undergone CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE). The authors then retrospectively applied the YEARS algorithm, the Wells’ score, and the “Wells’ score + d-dimer” to all patients, and compared their accuracy for diagnosing PE. We have several concerns regarding the reported findings. The authors identified that the “Wells’ score + d-dimer” was less sensitive than the YEARS algorithm: 71.8% versus 97.4%, respectively. We are puzzled about this finding, as this implies that some patients with PE had a negative “Wells’ score + d-dimer” result while they had a positive YEARS algorithm result. This seems impossible because the “Wells’ score + d-dimer” rules out PE in patients with a Wells score less than or equal to 4 and a d-dimer test result less than 500 ng/mL, whereas the YEARS algorithm, consisting of three Wells’ items (2), does so at thresholds of less than 500 ng/mL (if one or more YEARS items) or less than 1,000 ng/mL (if no YEARS item). Consequently, by definition, the “Wells’ score + d-dimer” cannot be less sensitive than the YEARS algorithm. The same problem applies to the Wells’ score versus the “Wells’ score + d-dimer”: a lower sensitivity is reported when d-dimer is added to a low Wells’ score, but this can only increase sensitivity. The authors do not report the 2 × 2 tables corresponding to the evaluation of the “Wells’ score + d-dimer,” making it impossible to verify how they arrived at the reported accuracy estimates. This is unfortunate because there is sufficient prior evidence showing that the Wells’ score should always be used in combination with d-dimer testing, and not as a standalone test (3). Thus, the article’s focus on the comparison between the YEARS algorithm versus the Well’s score without d-dimer is clinically poorly relevant. Additionally, it is unclear which role d-dimer testing and the Wells’ score played in the flow of participants in the study and thus whether all consecutive patients with suspected PE were included. The authors report that “as standard clinical practice at the facility, all patients with suspected PE undergo CTPA. ” However, if this is the case, it is unclear why all patients underwent d-dimer testing. Later on, they declare that “Wells’ score was found to have been applied in 92 patients. ” These observations suggest that d-dimer testing and the Wells’ score might have been used as triage tests, leading to the exclusion of low-risk patients and, consequently, inflated estimates of sensitivity and deflated estimates of specificity. That such a selection bias may have occurred is reflected by the fact that 87% of patients in the current study by Abdelaal Ahmed Mahmoud M Alkhatip et al (1) had a positive YEARS algorithm, compared to only 52% in the original YEARS study (4). Complete reporting of studies is crucial to enable assessing if findings are valid and generalizable. To ensure that all essential information is provided, we recommend authors, peerreviewers, and editors to adhere to reporting guidelines such as Standards for Reporting of Diagnostic Accuracy Studies (STARD) 2015 for diagnostic accuracy studies (5). The authors have disclosed that they do not have any potential conflicts of interest.