The Diagnostic Value of Kinetics of NLR to Identify Secondary Pulmonary Bacterial Infection Among COVID-19 Patients at Single Tertiary Hospital in Indonesia

PURPOSE: Coronavirus disease 2019 (COVID-19) is a new respiratory tract infection caused by severe acute respiratory syndrome coronavirus-2. The presence of secondary pulmonary bacterial infection (SPBI) made COVID-19 difficult to treat. Neutrophil-lymphocyte count ratio (NLR) is a systemic inflammatory marker used in the diagnosis and prognosis of viral or bacterial infection. At the first 3–5 days after hyperinflammation, it occurs in relation to clinical outcome. Therefore, this study aimed to evaluate the diagnostic value of NLR based on leukocyte kinetics upon admission and after 72 hours among COVID-19 patients with or without SPBI. PATIENTS AND METHODS: This retrospective cross-sectional study analyzed medical records data of admitted patients with COVID-19 according to the International Classification of Disease 10th Revision (ICD-10) between January and December 2021. The list of patients was extracted and followed by a hand search to identify the inclusion or exclusion criteria and stratified into proven and non-proven SPBI based on clinical data. The study distinguished between SPBI by means of a cut-off value (COV) on the first (D1) and third day (D3), assessed using receiver operating characteristics (ROC), as well as determined the magnitude of sensitivity, specificity, and prevalence ratio. RESULTS: A screening process was conducted on 2902 COVID-19 patients, of which 236 were included, accounting for 8.1%. Among these patients, 87 (36.9%) were found to have proven SPBI. A considerable difference in NLR value between proven and non-proven SPBI was observed on both D1 (11.1 vs 4.2) and D3 (15.3 vs 5.2), with optimal COV of NLR on D1, D3 was found to be 5.29, 9.47, respectively (p < 0.001). CONCLUSION: NLR on the D1 and D3 distinguished the occurrence of SPBI among COVID-19 patients. The application of NLR assisted in the early determination of bacterial infection and helped in controlling the empirical use of antibiotics.