The Role of Procalcitonin in Severe COVID-19

Abstract

Background: The variability of Covid-19 severity between patients has driven efforts to identify prognosticating laboratory markers that could potentially guide clinical decision making. Procalcitonin (PCT) is classically used as a diagnostic marker in bacterial infections, but its role in predicting Covid-19 disease severity is emerging. We aim to identify the association between PCT and Covid-19 disease severity in a critical care setting and whether bacterial co-infection is implicated.Methods: We retrospectively reviewed Covid-19 patients who had PCT levels measured and were treated in a critical care setting at our institution between February to September 2020. Patient demographics, laboratory markers including peak procalcitonin values and corresponding haematological and biochemistry parameters and bacterial culture results were analysed. The primary outcomes were defined as requirement of invasive mechanical ventilation and inpatient mortality and the secondary outcome was defined as duration of invasive mechanical ventilation.Findings: In total 60 patients were included for analysis; 41 (68%) required invasive mechanical ventilation and 27 (45%) died as inpatient. Univariate analysis identified higher peak PCT levels significantly associated with both the requirement for invasive mechanical ventilation and inpatient mortality. Calculated odds ratios of peak PCT levels to the use of invasive mechanical ventilation and inpatient mortality were 3.2 (95% CI 1.2-8.2, p=0.02) and 2.6 (95% CI 1.1-6.2, p=0.03) respectively. There was a significant positive correlation between increased peak PCT levels with duration on invasive mechanical ventilation. No significant difference was found between mean peak PCT levels of patients with positive and negative bacterial cultures. Interpretation: Patients with elevated PCT levels are more likely to develop respiratory failure requiring prolonged invasive mechanical ventilation and are at an increased risk of in-hospital death. This association may be independent of bacterial co-infection. Further study is required to elucidate the mechanisms through which PCT is increased in severe Covid-19.Funding Statement: This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.Declaration of Interests: All authors understand the policy of declaration of interests. RH, AKJM, JK, PS, PC, IALW, DG, and CGM all declare that that they have no competing interests.Ethics Approval Statement: As a retrospective analysis using clinically collected, non-identifiable data, this work does not fall under the remit of National Health Service Research Ethics Committees. This study was approved by our institution’s Research, Quality improvement and Audit Department with reference FH205.