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. 2020 Aug 21;10(9):619.
doi: 10.3390/diagnostics10090619.

The Model for Early COvid-19 Recognition (MECOR) Score: A Proof-of-Concept for a Simple and Low-Cost Tool to Recognize a Possible Viral Etiology in Community-Acquired Pneumonia Patients during COVID-19 Outbreak

Gianluca Sambataro  1 , Mauro Giuffrè  2   3 , Domenico Sambataro  4   5 , Andrea Palermo  6 , Giovanna Vignigni  1 , Roberto Cesareo  7 , Nunzio Crimi  1 , Sebastiano Emanuele Torrisi  1 , Carlo Vancheri  1 , Lorenzo Malatino  5 , Michele Colaci  5 , Nicoletta Del Papa  8 , Francesca Pignataro  8 , Erik Roman-Pognuz  9 , Massimiliano Fabbiani  10 , Francesca Montagnani  10   11 , Chiara Cassol  10   11 , Lorenzo Cavagna  12 , Valentina Zuccaro  13 , Verena Zerbato  2 , Cristina Maurel  2 , Roberto Luzzati  2 , Stefano Di Bella  2
Affiliations

The Model for Early COvid-19 Recognition (MECOR) Score: A Proof-of-Concept for a Simple and Low-Cost Tool to Recognize a Possible Viral Etiology in Community-Acquired Pneumonia Patients during COVID-19 Outbreak

Gianluca Sambataro et al. Diagnostics (Basel). .

Abstract

This study aims to assess the peripheral blood cell count "signature" of Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) to discriminate promptly between COronaVIrus Disease 19 (COVID-19) and community-acquired pneumonia (CAP). We designed a retrospective case-control study, enrolling 525 patients (283 COVID-19 and 242 with CAP). All patients had a fever and at least one of the following signs: cough, chest pain, or dyspnea. We excluded patients treated with immunosuppressants, steroids, or affected by diseases known to modify blood cell count. COVID-19 patients showed a significant reduction in white blood cells (neutrophils, lymphocytes, monocytes, eosinophils) and platelets. We studied these parameters univariately, combined the significant ones in a multivariate model (AUROC 0.86, Nagelkerke PSEUDO-R2 0.5, Hosmer-Lemeshow p-value 0.9) and examined its discriminative performance in an internally-randomized validation cohort (AUROC 0.84). The cut-off selected according to Youden's Index (-0.13) showed a sensitivity of 84% and a specificity of 72% in the training cohort, and a sensitivity of 88% and a specificity of 73% in the validation cohort. In addition, we determined the probability of having COVID-19 pneumonia for each Model for possible Early COvid-19 Recognition (MECOR) Score value. In conclusion, our model could provide a simple, rapid, and cheap tool for prompt COVID-19 diagnostic triage in patients with CAP. The actual effectiveness should be evaluated in further, prospective studies also involving COVID-19 patients with negative nasopharyngeal swabs.

Keywords: COVID-19; SARS-CoV-2; blood cell count; coronavirus; diagnosis; interstitial lung disease; neutrophils; platelets; pneumonia; triage.

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Conflict of interest statement

C.V. is part of the F. Hoffmann-La Roche Ltd. and Boehringer Ingelheim Scientific board. He has received consulting fees and/or speaker fees from AstraZeneca, Boehringer Ingelheim, Chiesi, F. Hoffmann-La Roche Ltd., and Menarini. MF has received speakers’ honoraria and support for travel to meetings from Bristol-Myers Squibb (BMS), Gilead, Janssen-Cilag, Merck Sharp & Dohme (MSD), and ViiV Healthcare, and fees for attending advisory boards from BMS and Gilead and V.Z. (Valentina Zuccaro) has received speaking fees from AbbVie. G.S., M.G., D.S., A.P., G.V., S.E.T., R.C., N.C., L.M., M.C., N.D.P., F.P., E.R.P., F.M., C.C., S.P., L.C., V.Z. (Verena Zerbato), C.M., R.L., and S.D.B. declare that they have no conflict of interest associated with this study.

Figures

Figure 1
Figure 1
Univariate models probability plot. The vertical axis shows the probability of being SARS-CoV-2 positive according to each model. The horizontal axis shows the values of blood leukocytes (i.e., WBC, NEUT, LYM, and MON) and platelets, which are reported as leukocytes//platelets. Given the different amplitude of leukocytes and platelets blood concentration, their respective units of measure, as reported in the figure, should be multiplied by a factor of 103 (e.g., 1.5 leukocytes × 103/mm3 are equivalent to 1500 cells/mm3 and 60 platelets × 103/µL are equivalent to 60,000 cells/µL). WBC: white blood cell; NEUT: neutrophils; LYM: lymphocytes; MON: monocytes; EOS: eosinophils; PLT: platelets.
Figure 2
Figure 2
Multivariate model performance in training and validation cohorts. (A) The training cohort on the vertical axis represents the probability of being SARS-CoV-2 positive according to the Model for possible Early COvid-19 Recognition (MECOR) Score (horizontal axis). Logistic regression coefficients of probability are represented with robust 95% confidence intervals (light red area); (B) the validation cohort on the vertical axis represents the probability of being SARS-CoV-2 positive according to the MECOR Score (horizontal axis). Logistic regression coefficients of probability are represented with robust 95% confidence intervals (light blue area).
Figure 3
Figure 3
Discriminative ability of the MECOR Score in the training cohort (red line) and in the internal validation cohort (blue line).
See this image and copyright information in PMC

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