Researchers Find Strong Link between Abnormal Liver Tests and Poor COVID-19 Outcomes

Researchers at the Yale Liver Center (New Haven, CT, USA) have found that patients with COVID-19 presented with abnormal liver tests at much higher rates than suggested by earlier studies.

Previous studies in China found that approximately 15% of patients with COVID-19 had abnormal liver tests. The Yale study, which looked retrospectively at 1,827 COVID-19 patients who were hospitalized in the Yale New Haven Health system between March and April, found that the incidence of abnormal liver tests was much higher at between 41.6% and 83.4% of patients, depending on the specific test. Approximately one-quarter of patients in the study had abnormal liver tests prior to being admitted for the virus. But regardless of whether patients came to the hospital with existing liver problems or developed them during their COVID-19-related hospitalization, a strong association was observed between abnormal liver tests and the severity of the COVID-19 cases, the researchers said.

In all, the Yale researchers examined five liver tests, looking at factors such as elevations in aspartate aminotransferase (AST) and alanine transaminase (ALT), which indicate liver cell inflammation; an increase in bilirubin, which indicates liver dysfunction; and increased levels of alkaline phosphatase (ALP), which may indicate inflammation of bile ducts. They also discovered that higher levels of liver enzymes, or proteins released when the liver is damaged, were associated with poorer outcomes for these patients, including ICU admission, mechanical ventilation, and death. Additionally, the study noted a relationship between drugs used to treat severe COVID-19 and liver damage, most significantly the drug tocilizumab. Rather than the liver itself driving poorer outcomes in COVID-19 patients, the researchers believe that the organ is more likely “a bystander” affected by the hyperinflammation associated with COVID-19 and by the side effects of related treatments. The researchers have additional clinical and lab-based studies underway to further understand COVID-19’s impact on liver pathology.

“We observed a strong association between the use of COVID-19 medications and abnormal liver tests,” said senior author Dr. Joseph Lim, professor of medicine and director of the Yale Viral Hepatitis Program, but added that they could not confidently tease out that the abnormal tests were due to “drug-induced liver injury” as opposed to the disease.

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Yale Liver Center