Role of interleukin-6 in COVID-19 pneumonia as marker of cytokine storm and predictor of course during hospitalization: Prospective, observational study in tertiary care setting in India

Abstract

Abstract Background: Robust data on interleukin-6 (IL-6) are available in bacterial infection as marker of inflammation, and now it can be utilized in currently ongoing coronavirus disease-19 (COVID-19) pneumonia pandemic to guide treatment strategy as marker of inflammation. Methods: Prospective, observational, and 12 weeks’ follow-up study, included 2000 COVID-19 cases confirmed with reverse transcription–polymerase chain reaction. All cases were assessed with lung involvement documented and categorized on high-resolution computed tomography (HRCT) thorax, oxygen saturation (SpO2), IL-6 at the entry point, and follow-up. Age, gender, comorbidity, and bilevel positive airway pressure/noninvasive ventilation (BIPAP/NIV) use and outcome as with or without lung fibrosis as per CT severity. Statistical analysis is done by the Chi-square test. Results: In a study of 2000 COVID-19 pneumonia cases, age (<50 and >50 years) and gender have a significant association with IL-6. HRCT severity score at entry point has a significant correlation with IL-6 level (P < 0.00001) IL-6 level has a significant association with duration of illness (P < 0.00001). Comorbidities have a significant association with IL-6 level (P < 0.00001). IL-6 level has a significant association with SpO2 (P < 0.00001). BIPAP/NIV requirement has significant association with IL-6 level (P < 0.00001). Timing of BIPAP/NIV requirement during the course of hospitalization has significant association with IL-6 level (P < 0.00001). Follow-up IL-6 titer during hospitalization as compared to entry point abnormal IL-6 has significant association in post-COVID lung fibrosis (P < 0.00001). Follow-up IL-6 titer during hospitalization as compared to entry point normal IL-6 has significant association in post-COVID lung fibrosis (P < 0.00001). Follow-up IL-6 titer during hospitalization as compared to entry point abnormal IL-6 has significant association in predicting cytokine storm irrespective normal or abnormal of IL-6 at the entry point (P < 0.0001). Conclusions: IL-6 is sensitive and reliable marker of inflammation helped in predicting cytokine storm COVID-19 pneumonia by analyzing sequential titers. Il-6 has very important role in predicting severity of illness, progression of illness, and need for ventilatory support. Sequential IL-6 titers predicted course during hospitalization and final radiological outcome as post-COVID ling fibrosis or post-COVID sequelae.