Role of interleukin-6 in coronavirus disease 2019 pneumonia: sensitive marker of inflammation, a predictor of ventilatory support and early marker of post-coronavirus disease lung fibrosis. A single center experience

Background Robust data on interleukin-6 (IL-6) is available in bacterial infection, and now it can be utilized in the currently ongoing coronavirus disease 2019 (COVID-19) pneumonia pandemic to guide treatment strategy as a marker of inflammation. Patients and methods Prospective, observational, and 12 weeks follow-up study, included 1000 COVID-19 cases confirmed with reverse transcription PCR. All cases were assessed with lung involvement documented and categorized on high-resolution computed tomography thorax, oxygen saturation, IL-6 at the entry point, and follow-up. Age, sex, comorbidity, and bilevel positive airway pressure/noninvasive ventilation (BIPAP/NIV) use and outcome as with or without lung fibrosis as per computed tomography severity. Statistical analysis is done by χ2 test. Results In the study of 1000 COVID-19 pneumonia cases, age (<50 and >50 years) and sex has a significant associations with IL-6. High-resolution computed tomography severity score at entry point has significant correlation with IL-6 level (P<0.00001). IL-6 level has a significant association with duration of illness (P<0.00001) comorbidities has a significant association with IL-6 level (P<0.00001). IL-6 level has a significant association with oxygen saturation (P<0.00001). BIPAP/NIV requirement has a 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 with entry point abnormal IL-6 has a significant association in post-COVID lung fibrosis (P<0.00001). Follow-up IL-6 titer during hospitalization as compared with entry point normal IL-6 has a significant association in post-COVID lung fibrosis (P<0.00001). Follow-up IL-6 titer during hospitalization as compared with entry point abnormal IL-6 has a significant association in predicting cytokine storm irrespective normal or abnormal of IL-6 at entry point (P<0.0001). Conclusion IL-6 has documented a very crucial role in COVID-19 pneumonia in predicting the severity of illness, progression of illness, and ‘cytokine storm.’ Sequential IL-6 titers will help assess response to treatment during hospitalization and analyze post-COVID lung fibrosis.