Risk stratification of patients admitted to hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: development and validation of the 4C Mortality Score

Dear Editor,

We read with great interest the excellent study by Knight et al.[1], “Risk stratification of patients admitted to hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: development and validation of the 4C Mortality Score” which has been recently published in your esteemed journal. It is a succinctly written article and we would like to commend the authors for their outstanding effort. It is a topic of much interest to us and we would like to add a few points which we feel would enrich the discussion.

Brahier T et al. [2] reported that lung involvement visualised with ultrasound correlated to disease severity and that summarising this into a simple ordinal scoring system has potential to discriminate patient requiring hospitalisation and thus better allocate scarce resources. Lung ultrasonography (LUS) is reliable, cheap and easy to use as a triage tool for the early risk stratification in COVID -19 patients. LUS has already shown excellent performance to detect non-COVID-19 pneumonia, compared to CT as a reference standard, and matches the discriminative power of CT in patients with acute respiratory distress syndrome (ARDS). [3]

Various studies have shown the relevance of evaluating the levels of IL-6 and platelet count along with the parameters in the 4c mortality score. Both these parameters have an independent role in stratifying the covid -19 patients based on their severity. Since these are readily obtainable in clinical laboratories, their inclusion will boost the mortality predicting accuracy. [4,5]

REFERENCES

(1)Knight S R, Ho A, Pius R, Buchan I, Carson G, Drake TM, et al. Risk stratification of patients admitted to hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol:delopment and validation of the 4C MortalityScore. BMJ. 2020;370:m3339. doi: https://doi.org/10.1136/bmj.m3339.
(2) Brahier T, Meuwly PJ-Y, Pantet O, Vez M-J B, Donnet H G ,Hartley M-A et al. Lung ultrasonography for risk stratification in patients with COVID -19: a prospective observational cohort study. Clin Infect Dis. 2020;ciaa1408. https://doi.org/10.1093/cid/ciaa1408
(3) Mayo PH, Copetti R, feller-Kopman D, Mathis G, Maury E, Mongodi S, et al. Thoracic ultrasonography: a narrative review. Intensive Care Med. 2019;45(9):1200-11.
(4) Laguna–Goya R, Utero-Rico A, Talayero P, Lazaro-Lasa M, Ramirez-Fernandez A, Naranjo L, et al. IL-6 –based mortality risk model for hospitalized patients with COVID -19. J Allergy Clin Immunol. 2020. Doi: 10.1016/j.jaci.2020.07.009
(5) Lippi G, Plebani M, Henry MB. Thrombocytopenia is associated with severe coronavirus disease 2019 (COVID -19) infections: A meta–analysis. Clin Chim Acta. 2020 Jul;506:145-148. https://doi.org/10.1016/j.cca.2020.03.022