Procalcitonin, NLR, and Bacterial Co-Infection as Predictor in Severe-Critical Ill COVID-19 Patients

Abstract

In severe-critical cases of COVID-19, a cytokine storm leads to an excessive immune response. This immune response is associated with increased biomarkers such as Procalcitonin (PCT) and the neutrophil-lymphocyte ratio (NLR). The prevalence of bacterial co-infection in COVID-19 patients is still a subject of ongoing research. The study's main objective is to investigate the correlation between PCT, NLR and the occurrence of bacterial co-infection and its outcome. We conducted an observational retrospective cohort study between March 2020 and December 2022, analysing data from medical records and daily COVID-19 reports. The sample was collected using consecutive sampling, including adult patients with confirmed RT-PCR results and experiencing severe critical stages. Laboratory tests (Hb, NLR, eGFR, and microbiology culture) were required. We performed comparison tests and used ROC curve analysis. We studied 515 patients who fulfilled inclusion and exclusion criteria. Most patients experienced Berat disease (n=318; 61.7% people), with mortality cases reaching 298 people (57.9%). The average PCT value was 3.49±11.79 (0.01-108.96), and the average NRL value was 13.37±13.15(0.27-98.00). The correlation between PCT (OR 2.3, p=0.016), NLR value (OR 1.9, p=0.003), and disease severity was confirmed. Meanwhile, positive urine and sputum culture were associated with length of stay (LOS).