COVID Mortality, Intubation, and ICU Admission Rates Improved Markedly During First 20 months of Pandemic


MADISON — Rates of death, intubation, and admission to intensive care improved markedly during the first 20 months of the pandemic among adults hospitalized with COVID-19, according to a nationwide study led by the University of Wisconsin.

Gains varied by subpopulation, according to the paper published in PLOS ONE. These data provide important information on the course of COVID-19 and identify hospitalized patient groups at heightened risk for negative outcomes.

University of Wisconsin researchers collected and harmonized electronic health record data from 1.1 million COVID-19 patients across 21 United States health systems from February 2020 through September 2021. The analysis comprised data from 104,590 adult hospitalized COVID-19 patients.

Virtually all patient populations examined showed significant improvements in mortality rates during the study. However, some patient groups had relatively high mortality rates both early and late in the pandemic:

  • Males.
  • Medicare members.
  • People who are severely obese.
  • Those aged 60 and older.

“The findings highlight both overall progress in battling the COVID pandemic and populations that remain at heightened risk for negative outcomes,” said Dr. Michael Fiore, a co-author of the paper and researcher at the University of Wisconsin. “These findings suggest the need for additional research to identify the clinical practices and treatments that contributed to the marked improvements in patient outcomes across sub-populations.”

The results show a marked decline in death rates, with mean unadjusted rates falling from 18.6% in the first three months to 7.3% in the last three months of the study period. Similar declines were seen with adjustment for age, sex, race, ethnicity, BMI, insurance status, and comorbidities. The greatest decline in mortality occurred early in the pandemic with modest increases in mortality occurring when hospital admissions increased (from November 2020 to January 2021 and from July 2021 to September 2021). Importantly, even though hospital admissions during the July to September 2021 peak exceeded levels seen early in the pandemic, mortality rates were about half of those seen early in the pandemic.

The present study found that Black hospitalized patients had a significantly lower mortality rate than White patients during the first 3 months of the pandemic. Hispanic patients had a significantly lower mortality rate by the end of the study period (both with unadjusted rates). It is unknown why Black individuals suffered higher mortality rates in some published studies and not this one.

The COVID EHR Cohort at the University of Wisconsin (CEC-UW) is a retrospective cohort study funded by the National Cancer Institute. Presented results include data from February 1, 2020, to September 30, 2021. Health systems from across the U.S. were invited to participate and 21 joined the cohort and transferred data regularly to the CEC-UW Coordinating Center in Madison, Wisconsin. Each data transfer included data dating back to February 1, 2020.