Procalcitonin is superior to lymphocytes, neutrophil-lymphocyte ratio and C-reactive protein for predicting 30-day all-cause mortality in COVID-19 patients at the Emergency Department

Pedro Lopez-Ayala, Ana Alcaraz-Serna, Adrian Valls Carbo, Maria Angeles Cuadrado Cenzual, María José Torrejón Martínez, Amanda López Picado, Carmen Martinez Valero, Juande D Miranda, Cristina Diaz del Arco, Gabriel Cozar Lopez, María del Mar Suárez-Cadenas, Pablo Jerez Fernández, Beatriz Angós, Esther Rodríguez Adrada, Eduardo Cardassay, Enrique del Toro, David Chaparro, María Teresa Montalvo Moraleda, Carolina Espejo Paeres, Miguel Ángel García Briñón, Victor Hernández Martín-Romo, Luis Ortega, Cristina Fernández Pérez, Mercedes Martínez-Novillo, Juan Jorge González Armengol, Juan González del Castillo, Christian Mueller, Francisco Javier Martín-Sánchez


Background: Demographic and clinical variables associated with death have been extensively characterized in COVID-19. Inflammation plays a key role, but the comparison and association between inflammatory biomarkers and 30-day all-cause mortality in COVID-19 patients has been less well studied.

Methods: Retrospective cohort study, including all consecutive patients with laboratory confirmed COVID-19 attended at the Hospital Clinico San Carlos Emergency Department having a baseline biomarker value for lymphocytes, neutrophil-lymphocyte ratio (NLR), C-reactive protein (CRP) and procalcitonin (PCT). Laboratory, clinical and treatment data were extracted from electronic medical records. The primary outcome was 30-day all-cause mortality. Associations between biomarkers and 30-day mortality was modelled using Cox Proportional Hazard regression with restricted cubic splines and evaluated by dose-response plots.

Results: Among 896 patients with all 4 biomarkers eligible for this study, 151 (17%) died within 30-days. Median age was 63 years (IQR 51-78) and 494 (55%) were male. Lymphocytes, NLR, CRP and PCT were significantly higher in patients who died (p<0.001). PCT was significantly superior for predicting 30-day all-cause death compared to lymphocytes, NLR and CRP (AUC 0.79 [95%CI 0.75-0.83] vs 0.70 [95%CI 0.65-0.74], P<0.001; 0.74 [95%CI 0.69-0.78], P=0.03; and 0.72 [95%CI 0.68-0.76], P<0.001, respectively). A PCT cut-off value of 0.06 ng/L for rule-out and 0.72 ng/L for rule-in allowed a direct triage decision in 357 patients (40%), achieving the predefined 95% sensitivity and specificity. Multivariable analysis showed stronger nonlinear dose-response association for PCT concentrations with 30-day all-cause death than for lymphocytes, NLR and CRP.

Conclusion: PCT provided the highest 30-day all-cause death prognostic accuracy in ED patients with COVID-19.

Palabras Clave

COVID-19; emergency department; procalcitonin; neutrophil-to-lymphocyte ratio; C-reactive protein.