#COVID #hospitalization #unreliable
“A new study reveals that nearly 50% of those hospitalized with COVID-19 had comorbities, mild or asymptomatic cases” — Paul Ebeling
From the beginning, COVID hospitalizations have served as a Key metric for tracking the risks posed by the disease.
Last Winter, the Atlantic described it as “the most reliable pandemic number,” while Vox quoted the cardiologist Eric Topol as saying that it’s “the best indicator of where we are.”
On the one hand, death counts offer finality, but they are a lagging signal and do noy account for people who suffered from significant illness but survived.
Case counts, on the other hand, depend on which and how many people happen to get tested.
Presumably, hospitalization numbers provide a more stable and reliable gauge of the pandemic’s truths, in terms of severe disease.
But a new, nationwide study of hospitalization records, released as a preprint today and not yet formally peer reviewed, suggests that the meaning of this gauge can easily be misinterpreted and misused, that it has shifted.
If you want to make sense of the number of COVID hospitalizations at any given time, you need to know how sick each patient actually is.
Until now, that’s been almost impossible to determine.
The federal government requires hospitals to report every patient who tests positive for COVID, yet the overall tallies of COVID hospitalizations, made available on various state and federal dashboards and widely reported on by the media, do not differentiate based on severity of illness.
Some patients need extensive medical intervention, such as getting intubated. Others require supplemental oxygen or administration of the steroid dexamethasone.
But there are many COVID patients in the hospital with mild symptoms, who have been admitted for observation on account of their comorbidities, or because they reported feeling short of breath.
Another group of the patients in this tally are in the hospital for something unrelated to COVID, and discovered that they were infected only because they were tested upon admission.
How many patients fall into each category has been a topic of speculation. In August, researchers from Harvard Medical School, Tufts Medical Center, and the Veterans Affairs Healthcare System decided to find out.
In 2 separate studies published in May, doctors in California read through several hundred charts of pediatric patients, one by one, to figure out why, exactly, each COVID-positive child had been admitted to the hospital.
Did they need treatment for COVID, or was there some other reason for admission, like cancer treatment or a psychiatric episode, and the COVID diagnosis was merely incidental? According to the researchers 40 to 45% of the hospitalizations that they examined were for patients in the latter group.
The authors of the paper out this wk took a different tack to answer a similar question, this time for adults.
Instead of meticulously looking at why a few hundred patients were admitted to a pair of hospitals, they analyzed the electronic records for nearly 50,000 COVID hospital admissions at the more than 100 VA hospitals across the country.
Then they checked to see whether each patient required supplemental oxygen or had a blood oxygen level below 94%. The latter criterion is based on the National Institutes of Health definition of “severe COVID.”
If either of these conditions was met, the authors classified that patient as having moderate to severe disease; otherwise, the case was considered mild or asymptomatic.
The study found that from March 2020 through early January 2021 before vaccination was widespread, and before the Delta variant had arrived the proportion of patients with mild or asymptomatic disease was 36%.
From mid-January through the end of June 2021 that number rose to 48%.
In other words, the study reveals that almost 50% of all the hospitalized patients showing up on COVID-data dashboards in Y 2021 were admitted for another reason entirely, or had only a mild presentation of disease.
This increase was even bigger for vaccinated hospital patients, of whom 57% had mild or asymptomatic disease.
But unvaccinated patients have also been showing up with less severe symptoms, on average, than earlier in the pandemic: The study found that 45% of their cases were mild or asymptomatic since January 21.
According to Shira Doron, an infectious-disease physician and hospital epidemiologist at Tufts Medical Center, in Boston, and 1 of the study’s co-authors, the latter finding may be explained by the fact that unvaccinated patients in the vaccine era tend to be a younger cohort who are less vulnerable to COVID and may be more likely to have been infected in the past.
An important implications of the study, these experts say, is that the introduction of vaccines strongly correlates with a greater share of COVID hospital patients having mild or asymptomatic disease.
“It’s underreported how well the vaccine makes your life better, how much less sick you are likely to be, and less sick even if hospitalized, That is the gem in this study.”
The study demonstrates that hospitalization rates for COVID, as cited by journalists and policy makers, are often misleading, and must be considered carefully.
COVID hospitalization tallies cannot be taken as a simple measure of the prevalence of severe or even moderate disease, because they inflate the true numbers by 2X.
Have a healthy, prosperous day, Keep the Faith!
