Procalcitonin, C-Reactive Protein-to-Mean Platelet Volume Ratio, and Neutrophil-to-Lymphocyte Ratio as Predictors of Secondary Bacterial Infections in COVID-19 Patients

Introduction: Coronavirus disease 2019 (COVID-19) can lead to secondary bacterial infections, particularly among critically ill patients. Differentiating between viral and bacterial infections is crucial for timely and appropriate antibiotic treatment. This study aimed to assess the predictive value of procalcitonin (PCT), C-reactive protein-to-mean platelet volume ratio (CRP-to-MPV ratio), and neutrophil-to-lymphocyte ratio (NLR) for secondary bacterial infections in COVID-19 patients. Methods: A retrospective analysis was conducted on COVID-19 patients admitted to RSUP dr. Sardjito between April 2020 and April 2021. Clinical data, procalcitonin levels, CRP-to-MPV ratio, NLR, culture results, and antibiotic susceptibility tests were analyzed. Statistical tests, including chi-square, t-tests and Mann-Whitney tests, were employed, with significance set at p<0.05. Receiver operating characteristic (ROC) analysis was performed to determine optimal cutoff values. Multivariate analysis was performed using logistic regression to ascertain the effects of multiple factors on the likelihood of developing secondary bacterial infections in COVID-19 patients. Results: Among 328 COVID-19 patients, 98 met the inclusion criteria. PCT had limited predictive value (AUC=0.535, p=0.638) with a sensitivity of 18.18 and specificity of 97.37 at a cutoff of 3.59. The CRP-to-MPV ratio showed slightly better predictive ability (AUC=0.587, p=0.198) with a sensitivity of 77.27 and specificity of 48.68 at the same cutoff value. The NLR demonstrated a higher predictive value (AUC=0.674, p=0.002) with a sensitivity of 90.91 and specificity of 44.74 at a cutoff of 3.64. Patients with an NLR of ≤3.64 exhibited an 8.01-fold elevated risk in the multivariate model. Conclusion: In COVID-19 patients hospitalized for up to seven days, an NLR greater than 3.64 can serve as a predictor of secondary bacterial infections. The use of NLR as a prognostic tool may aid in early identification and appropriate management of bacterial infections in COVID-19 patients. © 2024 Universiti Putra Malaysia Press. All rights reserved.