The Association between Admission Procalcitonin Level and The Severity of COVID-19 Pneumonia: A Retrospective Cohort Study

Abstract

Background and Objectives: An elevated procalcitonin level has classically been linked to bacterial infections. Data on the association between elevated procalcitonin and the outcome of coronavirus disease 2019 (COVID-19) are conflicting. Some linked it to associated bacterial co-infections, while others correlated the elevation with disease severity without coexisting bacterial infections. We aimed to investigate the association between high procalcitonin and the severity of COVID-19. Materials and Methods: Hospitalized patients with confirmed COVID-19 pneumonia were divided into two groups: the normal-procalcitonin group and the high-procalcitonin group (>0.05 ng/mL). Patients with concomitant bacterial infections on admission were excluded. The primary outcomes were the need for intensive care unit (ICU) admission, progression to invasive mechanical ventilation (IMV), and in-hospital 28-day mortality. Results: We included 260 patients in the normal procalcitonin group and 397 patients in the high procalcitonin group. The mean age was 55 years and 49% were females. A higher number of patients in the elevated procalcitonin group required ICU admission (32.7% vs. 16.2%, p < 0.001) and IMV (27.2% vs. 13.5%, p < 0.001). In-hospital mortality was significantly higher in the elevated procalcitonin group (18.9% vs. 8.5%, p < 0.001). After adjusting for other covariates, procalcitonin > 0.05 ng/mL was an independent predictor of progression to IMV (OR, 1.71; 95% CI, 1.08−2.71; p = 0.022), ICU admission (OR, 1.73; 95% CI, 1.13−2.66; p = 0.011), and in-hospital mortality (OR, 1.99; 95% CI, 1.14−3.47; p = 0.015). An elevated procalcitonin level was the strongest predictor of in-hospital mortality. Conclusions: Measurement of procalcitonin can have a prognostic role among COVID-19 patients. The admission procalcitonin level can identify patients at risk of ICU admission, progression to IMV, and in-hospital mortality.

Keywords: COVID-19; coronavirus disease; intensive care unit; mechanical ventilation; mortality; procalcitonin.

Figure 1

Flowchart demonstrating the patient selection process. Abbreviations: COVID-19, coronavirus disease 2019; PCT, procalcitonin; SARS-CoV-2, severe acute respiratory syndrome coronavirus-2. ^a Transfer of patients to a tertiary dedicated COVID-19 center, to decrease the burden on the district hospitals, was regularly arranged by the national health authorities during the pandemic. ^b Patients who were discovered positive on screening and referred to the medical COVID-19 ward for isolation only without evidence of pneumonia.

Figure 2

The primary outcomes in the normal and the high PCT groups. Abbreviations: ICU, intensive care unit; IMV, invasive mechanical ventilation; PCT, procalcitonin.

Figure 3

Risk factors for the main primary outcomes: (a) ICU admission, (b) IMV, and (c) Hospital mortality. For each variable, the black dot represents the odds ratio, and the horizontal line represents the 95% confidence interval. Abbreviations: CRP, C-reactive protein; PCT, procalcitonin; HTN, hypertension; ICU, intensive care unit; IMV, invasive mechanical ventilation.

Figure 3

Risk factors for the main primary outcomes: (a) ICU admission, (b) IMV, and (c) Hospital mortality. For each variable, the black dot represents the odds ratio, and the horizontal line represents the 95% confidence interval. Abbreviations: CRP, C-reactive protein; PCT, procalcitonin; HTN, hypertension; ICU, intensive care unit; IMV, invasive mechanical ventilation.