Author response to Letter to the Editor 'Liver impairment associated with disease progression in COVID-19 patients'.

Dear Editor,

This is an author response to the letter by Dr Benhong Zhou.

We chose the community‐acquired pneumonia (CAP) patients hospitalized in our hospital last year as the control because there was no suitable healthy control group available now. And considering the diverse aetiology of CAP, the liver impairment appeared in CAP patients maybe result from ischaemia/hypoxia‐reperfusion injury, systemic inflammatory response or drug use before hospitalization, besides the pathogen itself. In addition, we have excluded patients with confirmed chronic liver disease from both groups of COVID‐19 and CAP patients, which ruled out its influence on the analysis of our present study.

Due to focusing on the liver impairment in COVID‐19 patients, we have not included more laboratory indexes. And several studies have shown that the value of NLR was much more significant than lymphocytes in prediction of the COVID‐19 progression. Furthermore, our research has also shown that the liver impairment was related to inflammatory reaction, which was consistent with Lu L’s finding.

Since our data were mainly collected at the time of admission, these patients had not been treated with ventilators and drugs such as ridxivir and glucocorticoids. Therefore, the influence from all above factors could be excluded. During the novel coronavirus outbreak, it is difficult to confirm whether the involved patients have taken oral antibiotics or non‐steroidal drugs before admission. It should be noted that we have discussed the influence from those factors in the discussion part.

Generally, it is believed that the liver biochemical abnormalities in mild and common COVID‐19 patients are not significantly related to the prognosis and mortality, and the main causes of liver impairment in severe and critical cases may be ischaemia/hypoxia‐reperfusion injury and systemic inflammatory response, rather than the SARS‐Cov‐2 infection. Most COVID‐19 patients recover from liver impairment soon after their respiratory and circulation functions get improved.