Elucidating the role of procalcitonin as a biomarker in hospitalized COVID-19 patients.

Our objectives were to evaluate the role of procalcitonin in identifying bacterial co-infections in hospitalized COVID-19 patients and quantify antibiotic prescribing during the 2020 pandemic surge. Hospitalized COVID-19 patients with both a procalcitonin test and blood or respiratory culture sent on admission were included in this retrospective study. Confirmed co-infection was determined by an infectious diseases specialist. In total, 819 patients were included; 335 (41%) had an elevated procalcitonin (>0.5 ng/mL) and of these, 42 (13%) had an initial bacterial co-infection. Positive predictive value of elevated procalcitonin for co-infection was 13% while the negative predictive value was 94%. Ninety-six percent of patients with an elevated procalcitonin received antibiotics (median 6 days of therapy), compared to 82% with low procalcitonin (median 4 days of therapy) (adjusted OR:3.3, P < 0.001). We observed elevated initial procalcitonin in many COVID patients without concurrent bacterial co-infections which potentially contributed to antibiotic over-prescribing.