Hospitalized patients with COVID-19 have high rates of acute respiratory distress syndrome (ARDS). In one case series from Wuhan, China, a third of hospitalized patients infected with SARS-CoV-2 developed ARDS, and over half of those patients died. A new study we’ve just published sheds light on the mortality attributable to ARDS in sepsis patients, and provides a mortality benchmark for future studies of patients with COVID-19.

ARDS is a rapidly progressive disease that is characterized by acute respiratory failure, low oxygen, and fluid in the lungs. The most common risk factor for developing ARDS is infection, namely sepsis. Despite countless clinical trials targeting the syndrome, there are no disease-specific treatments known to improve outcomes in patients with ARDS. However, patients with ARDS are critically ill and often have other acute organ failures. One barrier to finding effective treatments may be that patients develop other competing causes of death – they may not necessarily die from ARDS, but rather with ARDS.

It has been difficult to determine what proportion of mortality is attributable to ARDS itself and what is driven by the underlying illness and comorbidities. In this new study, using two prospective cohorts of critically ill patients with sepsis, my colleagues and I estimate the excess mortality among patients with ARDS that can be attributed to ARDS. We found the attributable mortality to be 27% in one cohort and 37% in the other.

This study is the first to estimate the attributable mortality of ARDS patients with sepsis, a population that includes the sickest patients infected by SARS-CoV2. As we seek ways to combat SARS-CoV2, researchers should apply these findings to inform clinical trial design.

Trials of ARDS-targeted therapies need to be adequately powered to identify improvements in mortality. These findings can help guide decisions on trial size. Also, given that the excess mortality observed in ARDS patients was driven nearly entirely by patients with severe ARDS, the study suggests that targeting enrollment of patients with severe ARDS may be the most effective strategy for testing interventions that successfully treat this disease and give us more tools to fight this pandemic.

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The article, “Acute respiratory distress syndrome–attributable mortality in critically ill patients with sepsis,” was published in Intensive Care Medicine on March 25, 2020. The authors are Catherine L. Auriemma, Hanjing Zhuo, Kevin Delucchi, Thomas Deiss, Tom Liu, Alejandra Jauregui, Serena Ke, Kathryn Vessel, Matthew Lippi, Eric Seeley, Kirsten N. Kangelaris, Antonio Gomez, Carolyn Hendrickson, Kathleen D. Liu, Michael A. Matthay, Lorraine B. Ware & Carolyn S. Calfee.