A simple tool to help ruling-out Covid-19 in the emergency department: derivation and validation of the LDH-CRP-Lymphocyte (LCL) score
After the outbreak of the Covid-19 pandemic, cases of SARSCoV- 2 infections may gradually decrease in the next months. Given the reduced prevalence of the disease, Emergency Departments (ED) are starting to receive more and more non- Covid19 patients. Thus, a way to quickly discriminate ED patients with potential Covid-19 infection from non-Covid19 patients is needed in order to keep potentially contagious patients isolated while awaiting second-level testing. In this paper, we present the derivation and validation of a simple, practical, and cheap score that could be helpful to rule out Covid-19 among ED patients with suspicious symptoms (fever and/or dyspnoea). The LCL score was derived from a cohort of 335 patients coming to the ED of our hospital from March 16th to April 1st, 2020. It was then retrospectively validated in a similar cohort of 173 patients admitted to our ED during April. The score is based on blood values of lactate dehydrogenase, C-reactive protein, and lymphocyte count. The LCL score performed well both in the derivation and in the validation cohort, with an AUC respectively of 0.81 (95% CI: 0.77 – 0.86) and of 0.71 (95% CI: 0.63 – 0.78), given the difference in Covid- 19 prevalence between the two cohorts (57% vs 41% respectively). An LCL score equal to 0 had a negative predictive value of 0.92 in the derivation cohort and of 0.81 in the validation cohort, with a negative likelihood ratio respectively of 0.08 and 0.36 for Covid- 19 exclusion. This score could, therefore, constitute a useful tool to help physicians manage patients in the ED.
Ji D, Zhang D, Xu J, et al. Prediction for Progression Risk in Patients with COVID-19 Pneumonia: the CALL Score [published online ahead of print, 2020 April 9th]. Clin Infect Dis. 2020;ciaa414. DOI: https://doi.org/10.1093/cid/ciaa414
Shi Y, Yu X, Zhao H, et al. Host susceptibility to severe COVID-19 and establishment of a host risk score: findings of 487 cases outside Wuhan. Crit Care. 2020;24(1):108. DOI: https://doi.org/10.1186/s13054-020-2833-7
Kurstjens S, van der Horst A, Herpers R, et al. Rapid identification of SARS-CoV-2-infected patients at the emergency department using routine testing. Clin Chem Lab Med. 2020 Jun 29;58(9):1587-1593. DOI: https://doi.org/10.1515/cclm-2020-0593
Santotoribio JD, Nuñez-Jurado D, Lepe-Balsalobre E. Evaluation of Routine Blood Tests for Diagnosis of Suspected Coronavirus Disease 2019. Clin Lab. 2020 Sep 1;66(9). DOI: https://doi.org/10.7754/Clin.Lab.2020.200522
Kline JA, Courtney DM, Kabrhel C, et al. Prospective multicenter evaluation of the pulmonary embolism rule-out criteria. J Thromb Haemost. 2008;6(5):772‐780. DOI: https://doi.org/10.1111/j.1538-7836.2008.02944.x
Nazerian P, Mueller C, Soeiro AM, et al. Diagnostic Accuracy of the Aortic Dissection Detection Risk Score Plus D-Dimer for Acute Aortic Syndromes: The ADvISED Prospective Multicenter Study. Circulation. 2018;137(3):250‐258. DOI: https://doi.org/10.1161/CIRCULATIONAHA.117.029457
Watson J, Whiting PF, Brush JE. Interpreting a COVID-19 test result. BMJ. 2020;369:m1808. DOI: https://doi.org/10.1136/bmj.m1808
- Abstract views: 226
- PDF: 95
Copyright (c) 2020 The Authors
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.