In mid-March, about a week after the coronavirus disease (COVID-19) pandemic hit New York City, Christopher M. Petrilli, MD, received an ambitious assignment: Daniel J. Widawsky, NYU Langone’s chief financial officer, and Fritz François, MD, chief medical officer and patient safety officer, asked Dr. Petrilli to develop a deeper understanding about the patients being treated for the virus. The research that had come out of China and Italy, early novel coronavirus hotspots, had been largely descriptive. “We suspected that older patients were more likely to have negative outcomes, but given the urgency of the crisis, we needed to understand what factors put patients at higher risk,” says Dr. Petrilli.

So Dr. Petrilli, clinical lead for value-based medicine and medical director of clinical documentation improvement, began assembling a team to mine Epic, NYU Langone’s electronic health record (EHR) system. Nader Mherabi, executive vice president and vice dean, chief digital and information officer, suggested that he reach out to Yelena Chernyak, lead developer for Medical Center Information Technology, to pull and organize patient data. Next, Dr. Petrilli turned to Steven Chatfield, assistant vice president of decision support and value improvement, whose team provided data and analytic support throughout the project. Finally, at a preliminary presentation of the research results, he was fortunate to find a partner in Leora Horwitz, MD, director of the Center for Healthcare Innovation and Delivery Science, who has built a career leveraging big data to improve the quality and safety of healthcare. “She quickly figured out how to take our work to the next level by creating a more rigorous analytic process using advanced modeling techniques,” says Dr. Petrilli.

The team compiled detailed demographics for nearly 5,300 patients with COVID-19 treated across the institution. Their landmark study, published in The BMJ on May 22, remains the most comprehensive report of outcomes among patients hospitalized with COVID-19 in the United States, a game changer that has boosted clinical knowledge about who is affected most acutely by the virus and how to spot them earlier. Among the key findings: patients with oxygen saturation levels below 88 percent, the benchmark for hypoxia, and those with elevated blood markers for inflammation and the presence of blood clots, tend to have the worst outcomes. “Labs explain a lot about this disease,” says Dr. Horwitz. “We have incorporated these blood tests and oxygen readings into our COVID-19 protocols at NYU Langone to make sure these higher-risk patients are monitored closely.”

The study further revealed that obesity, independent of comorbidities like high blood pressure and diabetes, is a notable risk factor for both hospitalization and severe illness due to COVID-19. The finding is significant given that more than 40 percent of U.S. adults are obese, defined as having a body mass index of 30 or above. “There are not many obese people in China, so it wasn’t initially on anybody’s radar,” says Dr. Horwitz, who notes that it is not clear whether obesity’s link to inflammation or the impact of the condition on lung capacity accounts for the heightened risk.

“This is not a pure lung disease,” says Leora Horwitz, MD, director of the Center for Healthcare Innovation and Delivery Science. “This is a respiratory disease that causes blood clots and inflammation, that causes kidney failure, that causes strokes.”

Like obesity, heart failure and kidney disease are associated with inflammation, and both were shown to raise the risk for critical illness. By contrast, asthma and chronic obstructive pulmonary disease (COPD), two chronic inflammatory airway diseases, were not. That surprised the researchers and has enhanced the broader understanding of the novel coronavirus. “This is not a pure lung disease,” says Dr. Horwitz. “This is a respiratory disease that causes blood clots and inflammation, that causes kidney failure, that causes strokes.”

Perhaps the most encouraging finding of the study, which has been cited in more than 100 scientific publications and attracted inquiries from medical institutions in the United States and Europe, is that the rate of critical illness and death among hospitalized patients dropped significantly between March and May. This suggests that NYU Langone’s care has improved over time as clinicians have incorporated therapeutic techniques like proning (placing patients on their stomach to improve breathing) and the early use of anticoagulants for those at heightened risk for blood clots. As well, Dr. Horwitz believes that people—particularly those in high-risk categories—have become more compliant in adhering to community safety measures, such as wearing a mask and social distancing, resulting in lower viral load exposure.

Although a single-institution study poses limits in its demographic makeup, Dr. Petrilli points out two factors that help broaden this one. First, Epic is deployed in all NYU Langone hospitals, comprising a diverse mix of urban, suburban, and high- and low-income patients that make it generalizable. Second, unlike some health systems, NYU Langone’s EHR combines data from inpatients and outpatients at its 260 ambulatory practices, enabling a complete snapshot of its COVID-19 care. Says Dr. Horwitz, “We are the only institution in New York City to be able to do this kind of modeling of our data.”