419 - Diagnostic Utility of a Ferritin to Procalcitonin Ratio to Differentiate Patients with COVID-19 from Those with Bacterial Pneumonia

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Co-Author(s)

KJ

Katherine C. Jankousky

Resident
University of Colorado Denver, School of Medicine
Aurora, Colorado
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
PH

Peter Hyson

Resident
University of Colorado Denver, School of Medicine
Aurora, Colorado
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Presenting Author(s)

Jin Huang

Medical Student
University of Colorado Denver, School of Medicine, Colorado
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Co-Author(s)

Daniel B. Chastain

Clinical Associate Professor
University of Georgia College of Pharmacy
Albany, Georgia
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Carlos Franco-Paredes

Faculty
Hospital Infantil de Mexico, Mexico and Instituto Conmemorativo de la Salud, Panama
Denver, CO
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Kristine M. Erlandson

Associate Professor
University of Colorado Anschutz Medical Campus
Aurora, CO
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
AH

Andres Henao-Martinez

Assistant Professor
University of Colorado Denver, School of Medicine
Aurora, Colorado
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
LS

Leland Shapiro

Associate Professor
Rocky Mountain Regional Veterans Affairs Medical Center
Denver, Colorado
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Background: Accurate, rapid, inexpensive biomarkers are needed to differentiate COVID-19 from bacterial pneumonia, allowing effective treatment and antibiotic stewardship. We hypothesized that the ratio of ferritin to procalcitonin (F/P) reflects greater viral activity and host response with COVID-19 pneumonia, while bacterial pneumonia would be associated with less cytolysis (lower ferritin) and more inflammation (higher procalcitonin), thus a lower F/P ratio.

Methods: We conducted a retrospective study of adult patients admitted to a single University hospital in the US through May 2020, during the COVID-19 pandemic. We compared F/P ratio of patients diagnosed with COVID-19 or bacterial pneumonia, excluding patients with COVID-19 and bacterial co-infections. In a logistic regression, we controlled for age, sex, body mass index (BMI), diabetes (DM), and hypertension (HTN). We used a receiver operating characteristic analysis to calculate the sensitivity and specificity of F/P values for the diagnosis of COVID-19 versus bacterial pneumonia.

Results: Of 218 patients with COVID-19 and 17 with bacterial pneumonia, COVID-19 patients were younger (56 vs 66 years, p=0.04), male (66% vs 24%, p=0.009), had higher BMI (31 vs 27 kg/m², p=0.03), and similar rates of HTN (59% vs 45%, p=0.3) and DM (32% vs 18%, p=0.2). The median F/P ratio was significantly higher in patients with COVID-19 (3195 vs 860, p=0.0003, Figure 1). An F/P ratio cut-off of ≥ 1250 generated a sensitivity of 78% and a specificity of 59% to correctly classify a COVID-19 case (Figure 2). When adjusted for age, gender, BMI, DM, and HTN, a ratio ≥ of 1250 was associated with significantly greater odds of COVID-19 versus bacterial pneumonia (OR: 4.9, CI: 1.5, 16.1, p=0.009).Figure 1. Ferritin to Procalcitonin Ratios of patients with COVID-19 and patients with Bacterial Pneumonia (controls).

Figure 2. Receiver Operating Characteristic Analysis of Ferritin to Procalcitonin Ratio Cut-off Values Predicting COVID-19 Diagnosis.

Conclusion: We observed an elevated F/P ratio in patients with COVID-19 compared to those with bacterial pneumonia. A F/P ratio ≥ 1250 provides a clinically relevant increase in pre-test probability of COVID-19. Prospective studies evaluating the discriminatory characteristics of F/P ratio in larger cohorts is warranted.