High Mortality Rates Reported in Large COVID-19 Study

Damian McNamara

September 01, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Factors including older age and certain comorbidities have been linked to more serious COVID-19 outcomes in previous research, and now a large dataset collected from hundreds of hospitals nationwide provides more detailed data regarding risk for mechanical ventilation and death.

Comorbidities such as cardiovascular disease, chronic kidney disease, and obesity also were associated with more severe COVID-19 outcomes in this observational study of 11,721 adults. History of pulmonary disease or smoking, interestingly, were not.

One expert urges caution when interpreting the results, however. Although the study found a number of risk factors for ventilation and mortality, she says the dataset lacks information on race and disease severity, and the sample may not be nationally representative. 

The investigators hope their level of granularity will further assist researchers searching for effective treatments and clinicians seeking to triage patients during the COVID-19 pandemic.

The study was published online August 28 in Clinical Infectious Diseases.

COVID-19 and Comorbidities

Dr Robert Brown, Jr

"What I found most illuminating was this whole concept of comorbid conditions. This provides suggestive data about who we need to worry about most and who we may need to worry about less," study author Robert S. Brown, Jr, MD, MPH, told Medscape Medical News.

Comorbid conditions included hypertension in 47% of patients, diabetes in 28%, and cardiovascular disease in 19%. Another 16% were obese and 12% had chronic kidney disease.

People with comorbid obesity, chronic kidney disease, and cardiovascular disease were more likely to receive mechanical ventilation compared to those without a history of these conditions in an adjusted, multivariable logistic analysis.

With the exception of obesity, the same factors were associated with risk for death during hospitalization.

In contrast, hypertension, history of smoking, and history of pulmonary disease were associated with a lower risk of needing mechanical ventilation and/or lower risk for mortality.

Furthermore, people with liver disease, gastrointestinal diseases, and even autoimmune diseases — which are likely associated with immunosuppression — "are not at that much of an increased risk that we noticed it in our data," Brown said.

"As I tell many of my patients who have mild liver disease, for example, I would rather have mild liver disease and be on immunosuppressant therapy than be an older, obese male," he added.

Assessing data for people in 38 US states, and not limiting outcomes to patients in a particular COVID-19 hot spot, was a unique aspect of the research, said Brown, clinical chief of the Division of Gastroenterology and Hepatology at Weill Cornell Medicine in New York City.

Brown, lead author Michael W. Fried, MD, from TARGET RWE, in Durham, North Carolina, and colleagues studied adults from a commercially available Target Real-World Evidence (RWE) dataset of nearly 70,000 patients. They examined hospital chargemaster data and ICD-10 codes for COVID-19 inpatients between February 15 and April 20.

This population tended to be older, with 60% older than 60 years. A little more than half of participants, 53%, were men.

Key Findings

A total of 21% of patients died after a median hospital length of stay of 8 days.

Older patients were significantly more likely to die, particularly those older than 60 years (P < .0001).

Table. Age of patients and mortality rate

Age, Years Mortality Rate, %
18-40 2
41-60 14
>60 84


"This confirms some of the things we know about age and its impact on outcome," Brown said.

The risk for mortality among patients older than 60 years was 7.2 times that of patients between 18 and 40 years in an adjusted multivariate analysis. The risk for death for those between 41 and 60 years of age was lower (odds ratio [OR], 2.6) compared with the youngest cohort.  

Men were more likely to die than women (OR, 1.5).

When asked if he was surprised by the high mortality rates, Brown said, "Having worked here in New York? No, I was not."

Mechanical Ventilation and Mortality

Male sex, age older than 40 years, obesity, and presence of cardiovascular or chronic kidney disease were risk factors for mechanical ventilation.

Among the nearly 2000 hospitalized adults requiring mechanical ventilation in the current report, only 27% were discharged alive. "The outcomes of people who are mechanically ventilated are really quite sobering," Brown said.

People who ever required mechanical ventilation were 32 times more likely to die compared with others whose highest level of oxygenation was low-flow, high-flow, or no oxygen therapy in an analysis that controlled for demographics and comorbidities.

Furthermore, patients placed on mechanical ventilation earlier — within 24 hours of admission — tended to experience better outcomes.

COVID-19 Therapies?

Brown and colleagues also evaluated outcomes in patients who were taking either remdesivir or hydroxychloroquine. A total of 48 people were treated with remdesivir.

The four individuals receiving remdesivir who died were among 11 who were taking remdesivir and were also on mechanical ventilation.

"The data for remdesivir is very encouraging," Brown said.

Many more participants were treated with hydroxychloroquine, more than 4200 or 36% of the total study population.

A higher proportion of people treated with hydroxychloroquine received mechanical ventilation, 25%, versus 12% not treated with hydroxychloroquine.

The unadjusted mortality rate was also higher among those treated with the agent, 25%, compared to 20% not receiving hydroxychloroquine.

The data with hydroxychloroquine can lead to two conclusions, Brown said: "One, it doesn't work. Or two, it doesn't work in the way that we use it."

The researchers cautioned that their hydroxychloroquine findings must be interpreted carefully because those treated with the agent were also more likely to have comorbidities and greater COVID-19 disease severity.

"This study greatly contributes to understanding the natural course of COVID-19 infection by describing characteristics and outcomes of patients with COVID-19 hospitalized throughout the US," the investigators note. "It identified categories of patients at greatest risk for poor outcomes, which should be used to prioritize prevention and treatment strategies in the future."

Some Limitations

Dr Ninez A. Ponce

"The findings that patients with hypertension and who were smokers had lower ventilation rates, and patients with hypertension, pulmonary disease, who were smokers had lower mortality risks was very surprising," Ninez A. Ponce, PhD, MPP, told Medscape Medical News when asked to comment on the study.

Although the study identified multiple risk factors for ventilation and mortality, "unfortunately the dataset did not have race available or disease severity," said Ponce, director of the UCLA Center for Health Policy Research and professor in the Department of Health Policy and Management at the UCLA Fielding School of Public Health.

"These omitted variables could have a considerable effect on the significance, magnitude, and direction of point estimates provided, so I would be cautious in interpreting the results as a picture of a nationally representative sample," she said.

On a positive note, the study and dataset could illuminate the utility of medications used to treat COVID-19, Ponce said. In addition, as the authors note, "the data will expand over time." 

Brown has reported receiving grants and consulting for Gilead. Ponce has disclosed no relevant financial relationships.

Clin Infect Dis. Published online August 28, 2020. Full text

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