Background: Interleukin-8 (IL-8) is a pro-inflammatory cytokine that plays a key role in the pathogenesis of COVID-19. However, the dynamics of circulating IL-8 levels and their association with clinical outcomes in severe COVID-19 are not well understood.
Methods: We performed a prospective observational study of 100 patients with severe COVID-19 who were admitted to a tertiary care hospital in India. Circulating IL-8 levels were measured at baseline and on days 3, 5, and 7 of hospitalization. Clinical outcomes were assessed at 28 days.
Results: Circulating IL-8 levels were significantly higher in patients who died than in those who survived (mean: 24.1 pg/mL vs. 12.5 pg/mL; p<0.001). Patients with higher circulating IL-8 levels at baseline were more likely to develop acute respiratory distress syndrome (ARDS) and to require mechanical ventilation (p<0.05). In a receiver operating characteristic curve analysis, circulating IL-8 at baseline was a strong predictor of mortality (area under the curve: 0.86; p<0.001).
Conclusions: Circulating IL-8 levels are elevated in patients with severe COVID-19 and are linked to unfavorable clinical outcomes. IL-8 may be a useful biomarker for risk stratification and early intervention in severe COVID-19.