Association of Baseline Levels of C-Reactive Protein and Neutrophil to Lymphocyte Ratio in Assessing Severity and Mortality among COVID-19 Patients in Three Waves: A Cross-sectional Study

Abstract

Introduction: The Coronavirus Disease 2019 (COVID-19) infection has experienced three peaks in India, with possibilities of reinfections and future peaks. A comprehensive understanding of the disease, particularly in terms of inflammatory markers, is crucial. Neutrophil-to-Lymphocyte Ratio (NLR) and C-Reactive Protein (CRP) have been established as markers of disease severity in COVID-19 during the first wave, but limited data exists regarding these markers in the second and third waves. Aim: This study aims to investigate the association between baseline levels of CRP and NLR with disease severity and mortality among COVID-19 patients in three waves. Materials and Methods: A cross-sectional study was conducted at a tertiary care hospital in Bangalore from March 2020 to March 2022. The study included clinical data from 1485 patients with COVID-19. CRP and NLR levels were measured on the day of hospital visit, and their association with severity and mortality was assessed. Continuous variables were compared using independent t-test, one-way analysis of variance (ANOVA), or Kruskal-Wallis test as appropriate. Categorical variables were compared using the Chi-square test. Results: Wave 1 demonstrated a significant increase in CRP and NLR values among patients with critical illness (mean±SD: 11.96±11.9, 12.41±13.7) compared to other categories. The values of these two parameters in other categories of wave 1 were as follows: asymptomatic (2.28±6.0, 3.17±2.0), mild (1.67±3.4, 2.41±2.7), moderate (1.07±1.7, 3.71±2.4), and severe (6.47±7.2, 4.39±4.3). In wave 2, critical illness (10.52±8.9 and 10.73±7.8) showed elevated values compared to other categories (0.957±1.1, 2.61±1.7), (4.90±5.9, 4.27±4.1), (4.84±4.8, 4.03±2.4), (7.35±6.7, 7.10±6.7). In wave 3, the two parameters in critical cases (15.0±17.3 and 16.47±7.6) were elevated compared to other categories (3.67±2.9, 16.44±10.3), (3.3 and 13.9), (3.7±5.9, 19.10±1.6). Conclusion: CRP and NLR were found to be useful early markers for assessing disease severity and mortality in COVID19 patients across all three waves.

Keywords

• acute-phase proteins
• complete blood counts
• inflammatory markers
• pandemic
• pneumonia