Lymphocyte-to-C-reactive protein ratio may serve as an effective biomarker to determine COVID-19 disease severity

Objectives: We aimed to evaluate the ability of lymphocyte-C-reactive protein ratio (LCR) to discriminate between different levels of severity of COVID-19 disease. Methods: This retrospective observational single-center study was performed on 61 confirmed (PCR positive) COVID-19 patients between March and June 2020. The study population was separated into three groups: mild/moderate (n=24), severe (n=25) and critically ill (n=12). The optimal cutoff values of the LCR and neutrophil-to-lymphocyte ratio (NLR) in discriminating between patients with different severity levels were calculated by applying the receiver operating curve (ROC) analysis. Results: At baseline, the LCR decreased significantly across the three severity groups (mild/moderate > severe > critically ill). ROC analysis showed that a mean LCR of 43.21 was the cut-off value which best discriminated patients with the critically ill disease from severe patients (sensitivity: 84% and specificity: 69%). The discriminative performance of LCR (ROC AUC 0.820) was better than that of NLR (0.751) in this regard. LCR, unlike NLR was able to distinguish severe patients from mild/moderate patients, with a cut off value of 458.19 (sensitivity: 80% and specificity: 45%). Conclusion: LCR was observed to be able to distinguish COVID-19 infected patients of different severity (mild/moderate, severe and critically ill) and was superior to NLR in this regard.