UCI Health study in JAMA Network examines COVID-19 outcomes and mortality among hospitalized adults

Study finds that patients 80 years or older were age group with the highest mortality 

March 05, 2021

A new UCI Health study published in JAMA Network found that mortality of patients hospitalized with COVID-19 decreased drastically in the six months following the onset of the pandemic in March. This is the largest study to date examining the characteristics the outcomes of more than 192,000 hospitalized adults with COVID-19 utilizing data from 47 states. 

In March, 22.1% of 16,517 hospitalized patients died from COVID-19 compared to 6.5% of 17,776 patients hospitalized in August. The study found that mortality increased in association with increasing age, patients 80 years or older had the highest mortality while patients 30 years and younger had the lowest mortality. The most common comorbidities among those hospitalized included hypertension at 61.5%, diabetes at 38.4% and obesity at 27.4%.  

“Our study is representative of COVID-19 cases across the nation,” says Dr. Ninh T. Nguyen, chair, UCI Health Department of Surgery. “Our data found high mortality at the beginning of the pandemic with one death for every five patients admitted, which has improved, but still considered to be high with now one of 11 hospitalized COVID-19 patients.”

Among 192,550 adults hospitalized with the virus who were discharged from over 500 U.S. medical centers, 28.9% were admitted to the ICU, 13.6% died while hospitalized and 3% were transferred to hospice care. Patients not admitted to the ICU were in the hospital for a median of 6 days and those admitted to the ICU spent a median of 15 days in the hospital.  

Management of COVID-19 is rapidly changing, and this study didn’t compare courses of treatment. It’s also possible that at the beginning of the pandemic, COVID-19 was misdiagnosed due to the lack of widespread testing availability. Despite these limitations, this study provides data on characteristics and outcomes that to likely represents the largest U.S. cohort of hospitalized COVID-19 adults to date. 


UCI Health comprises the clinical enterprise of the University of California, Irvine. Patients can access UCI Health at primary and specialty care offices across Orange County and at its main campus, UCI Medical Center in Orange, California. The 417-bed acute care hospital provides tertiary and quaternary care, ambulatory and specialty medical clinics, and behavioral health and rehabilitation services. UCI Medical Center features Orange County’s only National Cancer Institute-designated comprehensive cancer center, high-risk perinatal/neonatal program and American College of Surgeons-verified Level I adult and Level II pediatric trauma center and regional burn center. UCI Health serves a region of nearly 4 million people in Orange County, western Riverside County and southeast Los Angeles County. Follow us on Facebook and Twitter.

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