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Observational Study
. 2020 Dec 17;15(12):e0243342.
doi: 10.1371/journal.pone.0243342. eCollection 2020.

Pre-test probability for SARS-Cov-2-related infection score: The PARIS score

Mickael Tordjman  1 , Ahmed Mekki  2 , Rahul D Mali  3 , Ines Saab  1 , Guillaume Chassagnon  1   4 , Enora Guillo  1 , Robert Burns  1 , Deborah Eshagh  5 , Sebastien Beaune  6 , Guillaume Madelin  3 , Simon Bessis  7 , Antoine Feydy  1   4 , Fadila Mihoubi  1 , Benoit Doumenc  8 , Luc Mouthon  9 , Robert-Yves Carlier  2   10   11 , Jean-Luc Drapé  1   4 , Marie-Pierre Revel  1   4
Affiliations
Observational Study

Pre-test probability for SARS-Cov-2-related infection score: The PARIS score

Mickael Tordjman et al. PLoS One. .

Abstract

Introduction: In numerous countries, large population testing is impossible due to the limited availability of RT-PCR kits and CT-scans. This study aimed to determine a pre-test probability score for SARS-CoV-2 infection.

Methods: This multicenter retrospective study (4 University Hospitals) included patients with clinical suspicion of SARS-CoV-2 infection. Demographic characteristics, clinical symptoms, and results of blood tests (complete white blood cell count, serum electrolytes and CRP) were collected. A pre-test probability score was derived from univariate analyses of clinical and biological variables between patients and controls, followed by multivariate binary logistic analysis to determine the independent variables associated with SARS-CoV-2 infection.

Results: 605 patients were included between March 10th and April 30th, 2020 (200 patients for the training cohort, 405 consecutive patients for the validation cohort). In the multivariate analysis, lymphocyte (<1.3 G/L), eosinophil (<0.06 G/L), basophil (<0.04 G/L) and neutrophil counts (<5 G/L) were associated with high probability of SARS-CoV-2 infection but no clinical variable was statistically significant. The score had a good performance in the validation cohort (AUC = 0.918 (CI: [0.891-0.946]; STD = 0.014) with a Positive Predictive Value of high-probability score of 93% (95%CI: [0.89-0.96]). Furthermore, a low-probability score excluded SARS-CoV-2 infection with a Negative Predictive Value of 98% (95%CI: [0.93-0.99]). The performance of the score was stable even during the last period of the study (15-30th April) with more controls than infected patients.

Conclusions: The PARIS score has a good performance to categorize the pre-test probability of SARS-CoV-2 infection based on complete white blood cell count. It could help clinicians adapt testing and for rapid triage of patients before test results.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Flow chart of patients included.
Fig 2
Fig 2. Receiver operating characteristic (ROC) curve of the PARIS score for the validation cohort.
Area under the curve = 0.919.
See this image and copyright information in PMC

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