Operational Definitions of COVID-19

Those of us in the process excellence and quality professions know the importance of operational definitions. Without a good operational definition, a metric is meaningless. An operational definition is a definition that includes a detailed specification of measurement. In process excellence work you will frequently discover that the opportunity your project is addressing can’t be reliably measured because it has not been operationally defined. Here’s an example of an actual operational definition used by a carpet manufacturer. Note that the definition describes the qualifications of the person making the evaluation, the standard of comparison, and the conditions under which the judgment is made.

Dark Blue Carpet. A carpet will be deemed to be dark blue if, judged by an inspector medically certified as having passed the U.S. Air Force test for color blindness; it matches the PANTONE color card 7462 C when both carpet and card are illuminated by GE “cool white” fluorescent tubes; card and carpet are viewed with the naked eye at a distance between 16-inches and 24-inches.

Early in my career I was an inspector in a can manufacturing plant and our largest customer returned a shipment of cans as “off color”. My supervisor and I inspected the cans and agreed that the customer was wrong (never a conclusion to be taken lightly!) We sent them the shipment again, and they returned it again with the note that there would be hell to pay if we didn’t stop sending them off-color cans! An investigation revealed that both I and my supervisor were color-blind. Not a good thing for lithography inspectors!

Here’s part of how the CDC defines “the flu”. The footnotes describe a number of fine points, such as false positives and negatives, and a “gold standard” test for sorting out the borderline cases.

What is a COVID-19 Case?

The European CDC defines “suspected case”, “probable case” and “confirmed case” separately. These definitions are hierarchical. Suspected cases require diagnostic testing, probable cases are suspected cases with inconclusive test results, and confirmed cases are persons with laboratory confirmation of virus causing COVID-19 infection, irrespective of clinical signs and symptoms. The question is: when we see data on “cases”, which are they, suspected, probable or confirmed? In the US it turns out that this is a judgment made by individual states. In Alabama, officials have ruled that one of every 10 people who died with COVID-19 did not die of COVID-19. Among those excluded from the numbers reported to the federal government were a bedbound patient with aspiration pneumonia in one lung and a person with a buildup of fluid and partial collapse of one lung.

Colorado, by contrast, has included some deaths where the disease caused by the novel coronavirus was deemed probable — based on symptoms and possible exposure — but not confirmed through a test.

In other words, the three kinds of COVID-19 cases are sometimes counted as COVID-19, and sometimes not. This disparity has huge implications, such as when New York City authorities on April 13 began reporting the deaths of people who were suspected of having COVID-19 but never tested. The city’s tally soared past 10,000 as the change added more than 3,700 fatalities.

What is a COVID-19 Death?

I’ve seen articles that say that often COVID-19 is listed as a cause of death regardless of whether or not it caused the death. Dr. Malcolm Kendrick reports

“…it was known that amongst the elderly who were dying, almost all of them had other serious medical conditions. Heart disease, high blood pressure, diabetes, chronic pulmonary disease and suchlike. This is often known in my line of work as “multimorbidity.””

But deaths of those with multimorbities are reported as COVID-19 deaths if the patient was COVID positive, regardless of if it was due to, for example, a heart attack or an automobile accident.

Conclusion

In public health, as in process excellence, operational definitions are necessary. Without them we simply don’t know what we’re talking about. Let’s start discussing what should and should not be included in the operational definition of COVID-19. Here’s are my operational definitions as a starting point.

Operational Definition of COVID-19 Case

A person will be deemed as a COVID-19 case if a RT-PCR Diagnostic Panel using only primers and probes labeled for EUA use and distributed by the International Reagent Resource detected the CDC 2019-nCoV virus in a specimen collected according to CDC approved collection procedures.

Operational Definition of COVID-19 Death

A death will be judged a COVID-19 death if in the opinion of a qualified medical professional COVID-19 was the primary cause or a major contributing cause of the death.

There you have it. Let me know your thoughts on these rough draft operational definitions in the comments.

Comments

  • Dick Borden April 19, 2020 at 8:08 pm Reply

    Covid 19 death is like a cancer death, I.e. few people actually die from cancer but of complications caused by the cancer. Covid 19 appears to target the pulmonary area but the news just reported a case where a male had to had a leg amputated due to covid 19.

    Dark Blue Color – have they heard of spectrophotometry? The color they’re looking for has a unique spectral wave length and can be specified as such negating the need for certified professionals to make the determination.

    • Thomas Pyzdek April 23, 2020 at 2:57 pm Reply

      Thanks for your thoughtful comment, Dick.

      So how is a death classified as caused by “cancer”? I don’t think that deaths are identified by the terminal diseases they caused or the comorbidities that the patient presented with. Or am I wrong?

      “have they heard of spectrophotometry? The color they’re looking for has a unique spectral wave length and can be specified as such negating the need for certified professionals to make the determination.”

      This was an old example and it was selected to illustrate an operational definition, not as a recommendation for how to inspect color. I think you’re suggesting another operational definition something like, “A specimen will be deemed to Dark Blue if a qualified technician using spectrophotometry [specify instrument] obtains a spectral wave length of X +- Y”.

  • Thomas Pyzdek April 19, 2020 at 9:06 pm Reply

    Thanks for your thoughtful comment, Dick.

    So how is a death classified as caused by “cancer”? I don’t think that deaths are identified by the terminal diseases they caused or the comorbidities that the patient presented with. Or am I wrong?

    “have they heard of spectrophotometry? The color they’re looking for has a unique spectral wave length and can be specified as such negating the need for certified professionals to make the determination.”

    This was an old example and it was selected to illustrate an operational definition, not as a recommendation for how to inspect color. I think you’re suggesting another operational definition something like, “A specimen will be deemed to Dark Blue if a qualified technician using spectrophotometry [specify instrument] obtains a spectral wave length of X +- Y”.

  • Thomas Pyzdek May 20, 2020 at 12:11 pm Reply

    On May 16, 2020 it was reported that The US was Dramatically Overcounting Coronavirus Deaths. The web site Town Hall reported that the definition what was a covid-19 case or death was simplistic. “The case definition is very simplistic,” Dr. Ngozi Ezike, director of Illinois Department of Public Health, explains. “It means, at the time of death, it was a COVID positive diagnosis. That means, that if you were in hospice and had already been given a few weeks to live, and then you also were found to have COVID, that would be counted as a COVID death. It means, technically even if you died of clear alternative cause, but you had COVID at the same time, it’s still listed as a COVID death.”

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