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AnnieGrace Haddorff (left) and Alec Newby (right) move a patient out of Gunnison Valley Health hospital in Gunnison, Colorado, on Nov. 26, 2021. The patient, who was experiencing atrial fibrillation, had to be transported to a larger hospital with an intensive care unit 65 miles away in Montrose. (Helen Santoro for KHN)

As Colorado’s hospitals work to keep up with an influx of patients during the state’s latest surge of coronavirus infections, two hospital systems have made an intriguing discovery: Most of their current patients who are positive for COVID are not in the hospital due to the disease.

Instead, the patients are what might be called incidental COVID patients — they were admitted to the hospital for reasons that are unrelated to COVID but were found to be infected after routine testing.

At UCHealth, officials on Tuesday announced the results of a review finding that about a third of their current COVID-positive patients were admitted for treatment for COVID, while the other two-thirds were admitted for something else. At Denver Health, medical director Dr. Connie Price said a review of patient records in January discovered that about 60% of the hospital’s COVID-positive patients had been admitted for reasons unrelated to the disease.

This is a change from previous waves. In August, Dr. Michelle Barron, UCHealth’s senior medical director of infection prevention and control, did a smaller review of COVID-positive patient records and found that about 95% of them had been admitted for treatment for the disease.

“So it’s a big turn in what we’re seeing now,” she said.

How omicron has changed COVID hospitalizations

The findings, though, are not exactly a surprise, and the omicron variant appears to be to blame. A December study out of South Africa — where the omicron variant was first identified — found a similar proportion of incidental COVID patients during that country’s omicron wave.

The exterior of the University of Colorado Hospital on the Anschutz Medical Campus in Aurora, photographed on Oct. 18, 2019. The hospital is the flagship of the UCHealth system. (John Ingold, The Colorado Sun)

Omicron’s extraordinary transmissibility is producing record numbers of infections every day across Colorado — more than double the state’s previous record daily highs, and state health officials believe they are also missing a significant number of new cases because of the state’s atronomical test positivity rate, which on Tuesday stood at nearly 30%. Meanwhile, omicron is on the whole producing less severe illness in individuals – especially those who are vaccinated. Combined, that means omicron is so widespread that it is showing up everywhere, including in people who happened to be hospitalized following an injury or a different illness.

Barron said she noticed the trend when she was taking care of patients last week but said she couldn’t be sure if she had just happened to treat an unrepresentative sample of patients. Now having the data in-hand, she said, “I’m saying ‘Wow, it wasn’t just me seeing this.’”

Estimating how many beds hospitals will need

The new analyses help provide context to a question that is vitally important to state health officials and researchers who are trying to predict how much hospital capacity Colorado needs to weather the omicron surge.

State epidemiologist Rachel Herlihy speaks during a news conference on the state’s response to the COVID-19 pandemic, Tuesday, Dec. 7, 2021, in Denver. (AP Photo/David Zalubowski)

Dr. Rachel Herlihy, the state epidemiologist at the Colorado Department of Public Health and Environment, first mentioned last week the state’s efforts to understand the issue — sometimes referred to as the “due to vs. with” question, as in whether someone is hospitalized due to COVID or just with COVID. Hospitals might be better equipped to handle a big influx of COVID-positive patients if most of those are part of the normal patient flow and not adding to that flow.

“I think it’s extremely challenging to model what is happening and will happen with omicron,” Beth Carlton, a professor of epidemiology at the Colorado School of Public Health, said last week in talking about uncertainty surrounding the “due to vs. with” question.

Colorado tracks coronavirus hospitalizations by recording the number of COVID-positive people who are admitted to the hospital. The numbers have always had the potential to scoop up some incidental COVID patients, as hospitals conduct COVID tests for every patient who is admitted. But doctors and other health leaders in Colorado have insisted during previous waves that the percentage of incidental COVID patients in the data was minimal, something Price, the Denver Health doctor, echoed Tuesday.

“Largely what we were seeing with delta and previous variants was that people who were testing positive were coming in for that reason,” Price said.

The challenge with tracking the ratio of “due to” vs. “with” is that it requires an in-depth review of patient medical records or looking at other types of aggregate data, something Herlihy said “lags quite a bit.”

“We don’t know at the beginning why someone is being hospitalized,” she said last week, referencing the time it takes to collect the data.

Since then, the state has conducted its own analysis using data on hospital admissions. Herlihy said Wednesday that the analysis showed that 80% to 90% of hospitalized, COVID-positive patients during earlier waves of infection were admitted to the hospital with COVID as their primary diagnosis. But over the first week of January, that percentage had dropped to 65%, another signal that incidental COVID hospitalizations are rising.

A chart based on an analysis by the Colorado Department of Public Health and Environment shows a decline during the omicron variant wave in the percentage of COVID-positive patients who are in the hospital due to their COVID symptoms. The chart was part of a presentation during a media briefing on Jan. 12, 2022. (Screenshot by John Ingold, The Colorado Sun)

News of the state’s analysis was first reported by KDVR-TV.

During a media briefing Wednesday, Herlihy said it was unclear why the state’s numbers show a much lower rate of incidental hospitalization that those from Denver Health or UCHealth. But she said it’s possible that the trends are not uniform across the state.

“There could quite likely be variability by region, so a hospital in one region of the state might be having a very different experience from a hospital in another region of the state,” she said.

Part of the story, not the whole story

The new analyses add more context to the question, but they also come with significant limitations and caveats.

For one, Barron said it’s unclear what happens to the COVID-positive patients after they are admitted. It’s true they may have been admitted for reasons unrelated to their infection, but do they develop COVID symptoms in the hospital that need treatment? Does the infection make it more difficult for them to heal from what originally brought them to the hospital?

Barron referred to UCHealth’s analysis as a snapshot.

“This obviously tells part of the story but it doesn’t tell all of the story,” she said.

She said the hospital system hopes to have more follow-up data later this week looking at patient outcomes as well as vaccination status.

Barron and Price also said the high percentage of COVID-positive patients who don’t need care for their infections belies another reality: There’s just a ton of patients coming in who do need care for a coronavirus infection.

On Tuesday, there were 1,488 patients in Colorado hospitals with a confirmed case of COVID — a single-day jump of 86 patients. Even if a good chunk of them aren’t there because of COVID, that still represents a sizable and growing wave of coronavirus patients that has the potential to strain hospital resources, especially as hospitals cope with a staff shortage due in part to their own workers getting sick.

“Just because it’s less doesn’t mean it’s zero,” Barron said. “And I think that’s important. There are still ramifications for getting COVID.”

Price said fewer COVID patients at Denver Health are being admitted to the intensive care unit and patients are generally spending fewer days in the hospital, both good signs. But some patients are still getting really sick — Price said especially those who are unvaccinated — and need a significant amount of care.

That means, for health care workers, the situation is hardly cheery, coming after nearly two years of grueling work during the pandemic. Price said it is especially difficult for staff to see yet another surge — no matter how high it climbs — when vaccines are available.

“I think they’re really feeling discouraged, to be perfectly honest,” Price said. “We know we’ll get through it. We always do. But these are difficult times for health care workers.”

John Ingold is a co-founder of The Colorado Sun and a reporter currently specializing in health care coverage. Born and raised in Colorado Springs, John spent 18 years working at The Denver Post. Prior to that, he held internships at...