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The most useful result here is to isolate the impact of covid hospital admission status on the probability of mortality, not the difference between covid and ot

The most useful result here is to isolate the impact of covid hospital admission status on the probability of mortality, not the difference between covid and other hospitalizations.

peytn 6y ago
Anyone who’s even dipped a toe in this policy area can tell you that when old people and hospitals meet, gaudy statistics follow. It’s common knowledge in the field. To not include that context or any points of comparison seems irresponsible to me given the publicity.
- nightpool 6y ago
  The excerpt from the study quoted above says "Rate ratios were greater for individuals aged less than 70 ... with the largest differences seen for respiratory disease (10.5 (95% confidence interval 9.7 to 11.4) for age less than 70 years v 4.6 (4.3 to 4.8) for age ≥70)" Isn't that a clear indication that there's something besides "general trends in old people" going on here?
  - incrudible 6y ago
    Age isn't the only factor, you need to control for underlying health conditions, which apparently they chose not to. Suppose you have COPD at age 50, for one you are less likely to live to 70, but also you are at a far greater risk with COVID. It would not be unexpected if such a person were readmitted to the hospital or die months later.
    - azakai 6y ago
      They did account for underlying health conditions. The control group was matched for relevant clinincal diagnoses, as well as general health factors like BMI and smoking (see "matching variables" section in the paper).
      - incrudible 6y ago
        I see that they were matched now, still the control group wasn't hospitalized, which must skew the result. Looking at the tables, you might get the idea that COVID hospitalization causes a lot of diabetes. The way they arrive at that is to count the diabetes diagnoses made after COVID admission. However to me it seems far more likely that a diabetic without a diagnosis (which is common) gets hospitalized with COVID, then gets their diabetes diagnosis in the ensuing medical surveillance. Having an undiagnosed liver or heart issue is also common.
        azakai 6y ago
        See the discussion above - it's very intentional that the control group wasn't hospitalized. It's the right approach for the question they are trying to answer, "how bad off is a person that got COVID and got hospitalized as a result of that". (There are other good questions to ask too, of course.)
        peytn 6y ago
        Given the discussion generated here and probably elsewhere, why do you believe the authors chose not to present a matched hospitalization control group alongside their control group? It’s pretty standard: that’s why they included a sentence saying they chose not to (albeit without any justification). Why deviate?
        azakai 6y ago
        As mentioned in the discussion above, their control group answers the question "if a person got COVID and was hospitalized because of it, how much worse off are they than had those things not happened?" They do justify their choice in the actual paper (e.g. see the end of the "Study population" section). (It's also interesting to compare COVID hospitalizations to other ones, say from a heart attack or allergic reaction, but those are different questions. For example, maybe a COVID hospitalization is less bad than one due to a heart attack, or worse than an allergy. Or maybe any hospital visit is just bad period. But given many people got hospitalized by COVID this year - something that never happened in the past - we need to know what that event cost them, that's the point of this study.)
- surfpel 6y ago
  > The increase in risk was not confined to the elderly and was not uniform across ethnicities > Rate ratios comparing patients with covid-19 and matched controls were greater in individuals aged less than 70 than those aged 70 or more for all outcomes > An alternative approach might have involved comparing outcomes after covid-19 and other hospital admissions; such research has recently been conducted with similar data sources to those in our own study (although with a smaller covid-19 cohort), and comparable rates of organ dysfunction were found between patients with covid-19 and patients with pneumonia who were discharged from hospital in 2019.36 We believe that our study design, where comparisons were made with the expected risk in the general population, was more relevant to public health policy, and complementary to the study that used non-covid hospital admissions as the comparison group. Also, the use of non-covid hospital admissions as the comparison group does not allow estimation of excess morbidity because non-covid admission does not necessarily represent an appropriate counterfactual situation to admission to hospital for covid-19, and the size and direction of the inferences will depend on the choice of control admissions.
Someone 6y ago
That’s the number this study went for, but it also is a number that doesn’t tell us anything about whether the increased chance of hospitalization and increased death rate are due to COVID, due to the first hospitalization, or due to those being hospitalized in the first place already being weaker than the general population. I wouldn’t call it the most useful one. If those who were admitted to a hospital with COVID already were less healthy than those who weren’t before they got COVID (and that’s a given. Higher lung capacity can keep you out of the hospital, for example), I don’t think it is a surprise they still aren’t as healthy when they leave the hospital.

The most useful result here is to isolate the impact of covid hospital admission status on the probability of mortality, not the difference between covid and other hospitalizations.

peytn 6y ago

Anyone who’s even dipped a toe in this policy area can tell you that when old people and hospitals meet, gaudy statistics follow. It’s common knowledge in the field. To not include that context or any points of comparison seems irresponsible to me given the publicity.

nightpool 6y ago
The excerpt from the study quoted above says "Rate ratios were greater for individuals aged less than 70 ... with the largest differences seen for respiratory disease (10.5 (95% confidence interval 9.7 to 11.4) for age less than 70 years v 4.6 (4.3 to 4.8) for age ≥70)" Isn't that a clear indication that there's something besides "general trends in old people" going on here?
- incrudible 6y ago
  Age isn't the only factor, you need to control for underlying health conditions, which apparently they chose not to. Suppose you have COPD at age 50, for one you are less likely to live to 70, but also you are at a far greater risk with COVID. It would not be unexpected if such a person were readmitted to the hospital or die months later.
  - azakai 6y ago
    They did account for underlying health conditions. The control group was matched for relevant clinincal diagnoses, as well as general health factors like BMI and smoking (see "matching variables" section in the paper).
    - incrudible 6y ago
      I see that they were matched now, still the control group wasn't hospitalized, which must skew the result. Looking at the tables, you might get the idea that COVID hospitalization causes a lot of diabetes. The way they arrive at that is to count the diabetes diagnoses made after COVID admission. However to me it seems far more likely that a diabetic without a diagnosis (which is common) gets hospitalized with COVID, then gets their diabetes diagnosis in the ensuing medical surveillance. Having an undiagnosed liver or heart issue is also common.
      - azakai 6y ago
        See the discussion above - it's very intentional that the control group wasn't hospitalized. It's the right approach for the question they are trying to answer, "how bad off is a person that got COVID and got hospitalized as a result of that". (There are other good questions to ask too, of course.)
        peytn 6y ago
        Given the discussion generated here and probably elsewhere, why do you believe the authors chose not to present a matched hospitalization control group alongside their control group? It’s pretty standard: that’s why they included a sentence saying they chose not to (albeit without any justification). Why deviate?
        azakai 6y ago
        As mentioned in the discussion above, their control group answers the question "if a person got COVID and was hospitalized because of it, how much worse off are they than had those things not happened?" They do justify their choice in the actual paper (e.g. see the end of the "Study population" section). (It's also interesting to compare COVID hospitalizations to other ones, say from a heart attack or allergic reaction, but those are different questions. For example, maybe a COVID hospitalization is less bad than one due to a heart attack, or worse than an allergy. Or maybe any hospital visit is just bad period. But given many people got hospitalized by COVID this year - something that never happened in the past - we need to know what that event cost them, that's the point of this study.)
surfpel 6y ago
> The increase in risk was not confined to the elderly and was not uniform across ethnicities > Rate ratios comparing patients with covid-19 and matched controls were greater in individuals aged less than 70 than those aged 70 or more for all outcomes > An alternative approach might have involved comparing outcomes after covid-19 and other hospital admissions; such research has recently been conducted with similar data sources to those in our own study (although with a smaller covid-19 cohort), and comparable rates of organ dysfunction were found between patients with covid-19 and patients with pneumonia who were discharged from hospital in 2019.36 We believe that our study design, where comparisons were made with the expected risk in the general population, was more relevant to public health policy, and complementary to the study that used non-covid hospital admissions as the comparison group. Also, the use of non-covid hospital admissions as the comparison group does not allow estimation of excess morbidity because non-covid admission does not necessarily represent an appropriate counterfactual situation to admission to hospital for covid-19, and the size and direction of the inferences will depend on the choice of control admissions.

Someone 6y ago

That’s the number this study went for, but it also is a number that doesn’t tell us anything about whether the increased chance of hospitalization and increased death rate are due to COVID, due to the first hospitalization, or due to those being hospitalized in the first place already being weaker than the general population. I wouldn’t call it the most useful one. If those who were admitted to a hospital with COVID already were less healthy than those who weren’t before they got COVID (and that’s a given. Higher lung capacity can keep you out of the hospital, for example), I don’t think it is a surprise they still aren’t as healthy when they leave the hospital.