The association between Interleukin-6 and C-Reactive Protein in Covid-19 patients

Background: Coronavirus Disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), is characterized by an excessive inflammatory response that may lead to cytokine storm and worsening clinical outcomes. Interleukin-6 (IL-6) is a major pro-inflammatory cytokine that stimulates the production of C-reactive protein (CRP), making both biomarkers useful for assessing the inflammatory response in patients with COVID-19. Objective: This study aimed to determine the association between serum IL-6 and CRP levels in patients with COVID-19. Methods: This retrospective observational study analyzed medical record data from 30 patients with COVID-19 confirmed by reverse transcription polymerase chain reaction (RT-PCR). Serum IL-6 and CRP levels were obtained from laboratory results recorded in hospital medical records. Statistical analysis was performed using IBM SPSS Statistics version 22. The association between serum IL-6 levels as the independent variable and CRP levels as the dependent variable was assessed using simple linear regression analysis. The results were reported as the regression coefficient (β), correlation coefficient (R), coefficient of determination (R²), and p-value. Results: Simple linear regression analysis demonstrated a significant positive association between serum IL-6 and CRP levels (β = 0.335; R = 0.538; R² = 0.290; p = 0.002). The positive regression coefficient indicated that higher serum IL-6 levels were associated with higher CRP levels. The R² value indicated that serum IL-6 explained 29.0% of the variation in CRP levels. Elevated IL-6 and CRP levels were observed in 90% and 93% of patients, respectively. Conclusion: Serum IL-6 levels were significantly and positively associated with CRP levels in patients with COVID-19. These findings suggest that IL-6 and CRP may provide complementary information for assessing the inflammatory response in patients with COVID-19.