COVID-19 Mortality Higher When ICUs Packed With COVID Patients

By Linda Carroll

January 20, 2021

(Reuters Health) - The more full an ICU is with COVID-19 patients, the higher the mortality rate, a new study finds.

An analysis of outcomes from more than 8,000 patients admitted to 88 VA hospitals revealed that the risk of mortality was almost two-fold higher during periods of peak COVID-19 ICU demand, according to the report published in JAMA Network Open.

The study holds a clear message for the public, said lead author Dr. Dawn Bravata, a physician scientist at the Richard L Roudebush VA Medical Center in Indianapolis, Indiana, and a professor of medicine and adjunct professor of neurology at the Indiana School of Medicine.

"The public should socially distance to avoid infection," Dr. Bravata said in an email. "The data show that mortality increases during periods of peak demand. Therefore, the more the public can do to avoid infections, the better."

Along with the public social distancing, "healthcare administrators can monitor their COVID-19 ICU-demand," Dr. Bravata said. "Facilities within a healthcare system or within a geographic region should collaborate to triage critically ill patients with COVID-19 to sites with greater ICU capacity to reduce strain on any one facility."

To investigate whether patients in ICUs strained by COVID-19 demand might do worse than those being treated when the demand was lower, the researchers turned to the VA Corporate Data Warehouse (CDW), which included patient information for the two years prior to COVID-19 diagnosis, along with death dates obtained from the CDW, VA Vital Status File, and the patient's electronic health record.

To evaluate ICU strain, the researchers calculated ICU load - the mean number of patients with COVID-19 in the ICU during the patient's hospital stay divided by the number of ICU beds at that facility. They also determined ICU demand - the mean number of patients with COVID-19 in the ICU during the patient's stay divided by the maximum number of patients with COVID-19 in the ICU.

The analysis included 8,515 patients with COVID-19 admitted to 88 VA hospitals between March and August 2020. Most patients (94.1%), were men and the average age was 67.9.

Mortality rates decreased over time, with 218 of 954 patients (22.9%) dying in March, 399 of 1,594 patients (25.0%) dying in April, 143 of 920 patients (15.5%) dying in May, 179 of 1,314 patients (13.6%) dying in June, 297 of 2,373 patients (12.5%) dying in July, and 174 of 1,361 (12.8%) patients dying in August.

The proportion of patients receiving care on general wards increased after the earliest months of the pandemic. In March, 527 COVID-19 patients (55.2%) received care on general wards; in April, 965 patients (60.5%); in May, 546 patients (59.3%); in June, 829 patients (63.1%); in July, 1,603 patients (67.6%); and in August, 903 patients (66.3%).

Both load and demand changed over time. The proportion of patients with COVID-19 treated during periods of low COVID-19 ICU load (less than or equal to 25%) increased over time, with 487 patients (51.0%) in March; 952 patients (59.7%) in April; 785 patients (85.3%) in May; 1,170 patients (89.0%) in June; 1,923 patients (81.0%) in July; and 1,250 patients (91.8%) in August.

Similarly, the proportion of patients with COVID-19 treated during periods of peak COVID-19 ICU load (>100%) decreased from 60 patients (6.3%) in March to 18 patients (1.1%) in April, to 0 patients in May through August.

Patients with COVID-19 who were treated in the ICU during periods of increased COVID-19 ICU demand had increased risk of mortality compared with patients treated during periods of low COVID-19 ICU demand. When COVID-19 ICU demand was 25% to 50%, the adjusted hazard ratio for all-cause mortality was 0.99; when demand was 50% to 75%, mortality aHR was 1.19; and when COVID-19 ICU demand was 75% to 100%, mortality aHR was 1.94.

No association between COVID-19 ICU demand and mortality was observed for patients with COVID-19 who were not in the ICU, the authors note.

"This is an important study," said Dr. Brian Garibaldi, medical director for the Johns Hopkins Biocontainment Unit in Baltimore. "It gets at something we all have been worried about: how much are outcomes impacted by the stress put on a given healthcare system by the number of patients with COVID-19. It's one of the first studies to put numbers behind concerns we all have."

There are some caveats to the study, said Dr. Garibaldi who was not involved in the research.

First, it's very hard to adjust for changes in COVID care over time. "While it suggests that ICU demand and load impact mortality, there are other things, such as who is getting beds and what treatments were available over time," he said.

It's possible that less-ill patients were getting sent to the ICU when demand was low, while very sick patients were sent there when demand was high, Dr. Garibaldi added. "Unfortunately, I think we are running that trial now," he said. "Many states had a lull over the summer and now there are surges across the country."

SOURCE: https://bit.ly/3oYfWDa and https://bit.ly/35VHpOk JAMA Network Open, online January 19, 2021.

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