Lymphocyte-to-C-Reactive Protein Ratio: A Novel Predictor of Adverse Outcomes in COVID-19

Background: Systemic inflammation elicited by a cytokine storm is considered a hallmark of coronavirus disease 2019 (COVID-19). This study aims to assess the validity and clinical utility of the lymphocyte to-C-reactive protein (CRP) ratio (LCR), typically used for gastric carcinoma prognostication, versus the neutrophil-to-lymphocyte ratio (NLR) for predicting in-hospital outcomes in COVID-19. Methods: A retrospective cohort study was performed to determine the association of LCR and NLR with the need for invasive mechanical ventilation (IMV), dialysis, upgrade to an intensive care unit (ICU) and mortality. Independent t-test and multivariate logistic regression analysis were performed to calculate mean differences and adjusted odds ratios (aORs) with its 95% confidence interval (CI), respectively. Results: The mean age for NLR patients was 63.6 versus 61.6, and for LCR groups, it was 62.6 versus 63.7 years, respectively. The baseline comorbidities across all groups were comparable except that the higher LCR group had female predominance. The mean NLR was significantly higher for patients who died during hospitalization (19 vs. 7, P ≤ 0.001) and those requiring IMV (12 vs. 7, P = 0.01). Compared to alive patients, a significantly lower mean LCR was observed in patients who did not survive hospitalization (1,011 vs. 632, P = 0.04). For patients with a higher NLR (> 10), the unadjusted odds of mortality (odds ratios (ORs) 11.0, 3.6 - 33.0, P < 0.0001) and need for IMV (OR 3.3, 95% CI 1.4 - 7.7, P = 0.008) were significantly higher compared to patients with lower NLR. By contrast, for patients with lower LCR (< 100), the odds of in-hospital all-cause mortality were significantly higher compared to patients with a higher LCR (OR 0.2, 0.06 - 0.47, P = 0.001). The aORs controlled for baseline comorbidities and medications mirrored the overall results, indicating a genuinely significant correlation between these biomarkers and outcomes. Conclusions: A high NLR and decreased LCR value predict higher odds of in-hospital mortality. A high LCR at presentation might indicate impending clinical deterioration and the need for IMV.