Procalcitonin Is Not a Reliable Biomarker of Bacterial Coinfection in People With Coronavirus Disease 2019 Undergoing Microbiological Investigation at the Time of Hospital Admission

Abstract

Admission procalcitonin measurements and microbiology results were available for 1040 hospitalized adults with coronavirus disease 2019 (from 48 902 included in the International Severe Acute Respiratory and Emerging Infections Consortium World Health Organization Clinical Characterisation Protocol UK study). Although procalcitonin was higher in bacterial coinfection, this was neither clinically significant (median [IQR], 0.33 [0.11-1.70] ng/mL vs 0.24 [0.10-0.90] ng/mL) nor diagnostically useful (area under the receiver operating characteristic curve, 0.56 [95% confidence interval, .51-.60]).

Keywords: COVID-19; SARS-CoV-2; coinfection; procalcitonin.

Figure 1.

Evaluation of admission procalcitonin as a biomarker of bacterial coinfection in coronavirus disease 2019. A, Comparison of admission procalcitonin concentrations between patients with positive and negative microbiology results within the first 2 days of admission. “Any” refers to either blood or respiratory samples, representing the entire cohort. Lines show the median. The gray shading identifies values ≤0.04 ng/mL, which is the mean concentration measured in healthy people [9]. Groups were compared with individual Mann-Whitney tests. P values shown are uncorrected. B, Receiver operating characteristic analysis for admission procalcitonin concentration in predicting absence of coinfection (considering patients with any microbiological sample available). C, Correlation matrix analysis of admission procalcitonin, C-reactive protein, total white cell count, neutrophil count, and lymphocyte count. The size and shading of circles represents the Spearman R value with a P value of <.05. An empty cell indicates no statistically significant correlation between the variables. Abbreviations: AUC, area under the curve; CI, confidence interval; CRP, C-reactive protein; Lø, lymphocyte count; Nø, neutrophil count; PCT, procalcitonin; WCC, white cell count.