Epidemiology and Antimicrobial Treatment Impact of Procalcitonin in Patients with COVID-19

ABSTRACT

Background. Procalcitonin (PCT) is often measured in patients with signs of bacterial infection. PCT is often elevated in bacterial pneumonia and septic shock and usually low in viral infections. Recent studies have found a correlation between PCT and disease severity in COVID-19, and most patients receive antibiotics despite bacterial co-infection being rare. We sought to characterize PCT trends in COVID-19, assess its relation to bacterial pneumonia, and assess its relation to clinical decision making around antimicrobial use. Methods. We included patients >=18 hospitalized at Michigan Medicine (3/1/20- 10/31/21), positive for COVID-19, with >= 1 PCT measurement. Structured query was used to retrospectively extract data. Patients started on an antibiotic underwent retrospective chart review by 2 reviewers for presence of bacterial pneumonia (bPNA), and were classified as having proven, probable, possible, or no bPNA (Figure 1). Multivariable models controlling for time from start of the pandemic, demographics, and comorbidities were used to determine associations of PCT and bPNA with antimicrobial use. Figure 1 Flow diagram of patients included in analyses Results. 793 patients met inclusion criteria, with 224 (28.2%) initiated on antibiotics. Of these 224, 33 (14.7%) had proven/probable bPNA, 125 (55.8%) had possible bPNA, and 66 (29.5%) had no bPNA. On average, patients had 2.6 +/-3.7 (mean +/-SD) PCT measurements, with 4.1 +/-5.2 if on antibiotics vs. 2.0 +/-2.6 if not. Initial PCT was higher in those on antibiotics and highest in those with proven/probable bPNA (Table 1). After adjustment for confounders, initial PCT was associated with antibiotic initiation (OR 1.68, 95% CI 1.47-1.91, p < 0.0001) (Table 2). Initial PCT (RR 1.11, 95% CI 1.03-1.20, p=0.008), change in PCT over time (RR 1.03, 95% CI 1.01-1.05, p=0.007), and bPNA category (RR 1.51, 95% CI 1.23-1.84, p < 0.0001) were associated with antibiotic duration (Table 3). Conclusion. PCT was elevated in patients with COVID-19, but more pronounced with bPNA. Antibiotics were started in > 25% of patients, regardless of bPNA. PCT trends associate with the decision to initiate antibiotics and treatment duration, independent of bPNA and comorbidities. Future prospective studies should determine if PCT can be used to safely make decisions around antibiotic treatment for bacterial infection during COVID-19.