ASA Connect

 View Only
Expand all | Collapse all

The meaning of excess deaths

  • 1.  The meaning of excess deaths

    Posted 05-18-2020 15:50
    ​I was wondering what people felt was the information that can be extracted from data on excess deaths.  Here in the United States, I feel the number gives an estimate of the number of people being kept alive by the medical system.  Where the system is disrupted, those who are dependent on the system (such as it is) are more likely to die, either because they cannot get necessary medications or necessary procedures, or because something prevents them from getting essential care.  I was wondering what other implications or explanations people can infer from knowledge of excess deaths?

    Raoul Burchette
    Biostatistician

    ------------------------------
    Raoul Burchette
    ------------------------------


  • 2.  RE: The meaning of excess deaths

    Posted 05-18-2020 22:30
    First of all, it is important to  adjust the deaths for population composition , especially age.
    Secondly, it is important to take into consideration variability in the number of deaths, particularly for smaller geographic areas.

    ------------------------------
    Elizabeth Smith
    Statistician
    ------------------------------



  • 3.  RE: The meaning of excess deaths

    Posted 05-19-2020 08:30
    ​On excess deaths.

    First, they are compared to past years for the same months.  To get a handle on this as Yale did (and hopefully will repeat by the end of July), it is not a perfect measure. But it gives us the best possible measure of the deaths that can be attributed to the pandemic. It could also be given stratified for age group, gender, and ethnicity.  It is all cause mortality, and preventable deaths caused by fear of getting medical help are legitimately attributable to the pandemic.  Traffic fatalities will be down, but they should still not be weeded out.  If the Yale figures from March 1-April 5 hold up, the excess death rate could be as much as double that being reported by the media.  That would make the excess death rate about 500 per year, making the US one of the highest.  By the way, in terms of deaths per million, tiny Belgium is the worst in Europe at about 1000 per mullion. Its small population puts in under the radar screen. Time will tell.

    ------------------------------
    Jon Shuster
    ------------------------------



  • 4.  RE: The meaning of excess deaths

    Posted 05-19-2020 22:45
    ​​Jon,

    I am not certain what the denominator is for the 500 per year excess death rate you anticipate.  I see you reference the Belgium (excess?) death rate as about 1000 per million, so should I assume the denominator should be per million? The U.S. Death rate last year was 8 782 per million (hence I am assuming the 1000 per million for Belgium is excess death rate).

    I am looking forward to seeing what we can gather about the age group, gender and ethnicity death rates.  I hope there will also be breakdown for underlying causes in due time.  The CDC tends to take about two years to release this information.  Will Yale be faster?  I believe the death rate is "age-adjusted" according to some kind of standard US population, often a particular Census year age distribution.  I think CDC also publishes the age and gender adjusted death rates and even the age, gender and race (crude category) adjusted death rate in their vital statistics releases.  What is fortunate for the statistics is that this was a census year, so the demographic data should be reasonable good, though I wonder about the quality of this census, since not everyone is online and I believe libraries were generally closed during that time.

    It would be very interesting to identify what proportion are preventable deaths caused by fear of getting medical help.  I don't know how long people have been looking at excess deaths for large scale disasters, I have only become aware of it since the Puerto Rico disaster about three years ago.  But I think it is useful information.  Puerto Rico had other issues complicating the death counts which the continental United States doesn't have, but perhaps if we track excess death in the United states for a while, we will get familiar enough to be able to anticipate the extent of excess death for a given scale event.  In disaster situations, people may not be able to get to medical help because they are physically prevented by the situation.  I think we will be able to identify an expected rate of death attributable to this as time and study goes on.

    I guess you can see I would like to analyze the components of excess death to see what we can learn.  I think this could be useful information in recognizing it isn't just the disaster, it is the other things that are so because of the disaster that can much increase the death rate directly attributed to the disaster.

    The absence of medical care decreases the death rate associated with elective procedures, but lack of medications can play havoc for those who need them to keep them from developing more fatal conditions.  I am thinking of things like hypertension and diabetes and chronic kidney disease and heart disease.  [I might say, not getting sufficient resistance exercise because the gyms are all closed has been a trial for me.]  This was the basis of my question initially.  I am curious about what proportion of the population actually falls into this class of people.  I don't think that "no access to proper medical care" is one of the underlying reasons put on the death certificate, but perhaps it should be.  I guess time will tell.

    ------------------------------
    Raoul Burchette
    Biostatistician
    ------------------------------



  • 5.  RE: The meaning of excess deaths

    Posted 05-20-2020 09:35
    There is a long history of using excess death calculations to understand the effect of large scale armed conflicts on population mortality (beyond counts of direct civilian and military casualties). The modern version of these ideas dates back at least to WWI where ironically there was also the need to consider the impact of the 1918-19 influenza pandemic. My colleagues discuss this in a historical paper "Counting civilian casualties: From the past to the future," Social Science History, 2018, 42, 379-410.

    ------------------------------
    Nicholas Jewell
    Chair in Biostatistics and Epidemiology
    London School of Hygiene & Tropical Medicine
    ------------------------------



  • 6.  RE: The meaning of excess deaths

    Posted 05-20-2020 10:23
    ​Nick Jewel's points apply well to combat deaths, but in the Covid-19 context, as long as you interpret excess deaths correctly, the Yale excess death projection, which needs to be updated at the end of July, makes perfect sense.  But for the pandemic, the situation for say March 1-June 30, 2020 would have overall deaths per million very much like it was for the same period of 2018 and 2019. Thus, excess deaths can be logically attributed to the pandemic. What cannot be assumed is that these excess deaths can be attributed purely to having a Covid-19 virus infection. But does it matter if it is directly due to the infection or an incidental result of the infection?  For example, purportedly, the suicide rate is  higher, the traffic fatalities are lower, people are dying because of fear to going to the hospital, etc.  When I was Group Statistician for the Pediatric Oncology Group, the main outcome for most trials was time to the earliest of recurrence, second cancer, or death from any cause.  Intent-to-treat was the gold standard. This is the most objective way to do the analysis. That outcome universally was approved by National Cancer Institute Peer review in hundreds of protocol designs. For example, suicide is considered a failure of the treatment, because it is illogical to handle it as anything else. The individual would be highly unlikely to take their life if they were cured of their disease and its implications. Excess deaths closely resembles this objective strategy. Finally, it is a very simple concept, easily explained to the non-scientific public at large.


    ------------------------------
    Jon Shuster
    ------------------------------



  • 7.  RE: The meaning of excess deaths

    Posted 05-20-2020 15:23
    ​Jon,

    While I would want to include suicides in the count, and even treat them as treatment failure, I am less comfortable trying to reason why people commit suicide.  Suicide seems to be largely an illogical activity.


    ------------------------------
    Raoul Burchette
    Biostatistician
    ------------------------------



  • 8.  RE: The meaning of excess deaths

    Posted 05-20-2020 11:34
    Although the Centers for Disease Control and Prevention issues guidelines to determine cause of deaths, underestimating the death toll of natural disasters, heatwaves, influenza, and other emergencies is common. In some cases, the underestimates can be extreme. Excess death analysis is really important to pinpoint the true death toll of an emergency. We also performed an excess death analysis in the US. We found strong evidence that COVID-19 deaths were undercounted in several states. It is possible, that the emergency may also lead to increased deaths due to causes other than COVID-19. Unfortunately, the timeliness of death certificate data is not good and substantially varies per state. There are some measures of completeness of the data, but not only their use may be subjective, but the mechanism that leads to the delay on mortality data may drastically change during the pandemic. Thus, there doesn't seem to be a robust way to adjust for mortality data undercounts.

    ------------------------------
    Roberto Rivera
    Professor
    ------------------------------



  • 9.  RE: The meaning of excess deaths

    Posted 05-20-2020 15:19
    ​Fortunately, the excess deaths count is not affected by under reporting of specific causes, though one would certainly hope the specific causes was good data.  But the timeliness issue could still lead to at least temporarily undercounting and certainly it would be hard to link the real time reported deaths to real time because of these issues.  Perhaps we will be able to identify a typical delay for specific locations and use it in the future to adjust for likely current death rates in each location.  It is more likely that we are going to have to wait for a clearer picture.

    One could hope the timeliness challenge may be incentive to attempt to use Artificial Intelligence or similar means to assist in streamlining the death attribution and reporting process.

    ------------------------------
    Raoul Burchette
    Biostatistician
    ------------------------------



  • 10.  RE: The meaning of excess deaths

    Posted 05-20-2020 21:43
    Edited by Roberto Rivera 05-20-2020 21:46
    The CDC mortality data is somewhat limited: weekly all-cause, pneumonia and influenza deaths for each state. The delay affects the recent data of essentially all states. Some more than others, yet thanks to the emergency still significant even for the states most on top of things (like NY and CA).

    Proxy data may be of use. For example, data weekly cremations, burials, etc. could be of use. Sadly, haven't found any current data at the right resolution. 

    Yes, seasonality is present in mortality data, but that is easily accounted for in excess deaths models.

    ------------------------------
    Roberto Rivera
    Professor
    ------------------------------



  • 11.  RE: The meaning of excess deaths

    Posted 05-20-2020 15:30
    ​Jon,

    In your first post you mentioned that if the trend in Yale study continues the US might be one of the highest as far as excess death rate goes.  What would you make of this, if it pans out?  What do you feel would be the take home message from that?  (For instance, what would be the explanation for this, and possibly, what could be done about it?)

    ------------------------------
    Raoul Burchette
    Biostatistician
    ------------------------------



  • 12.  RE: The meaning of excess deaths

    Posted 05-19-2020 22:59
    ​Elizabeth,

    This is a good point about population composition adjusting.  I think some of what I am hearing is not so adjusted but country specific rates are being published, even if they are properly adjusted to their own population, they may not translate from one country to another..  Unless these are adjusted to be in similar populations, the rates are difficult to compare.  And certainly variability in the estimated rates are important as well.

    Did you have some thoughts about what kinds of information could be gleaned from excess death information?

    ------------------------------
    Raoul Burchette
    Biostatistician
    ------------------------------



  • 13.  RE: The meaning of excess deaths

    Posted 05-19-2020 10:20
    excess deaths are not limited to those 'supported by the medical system'.  according to an analysis done by the economist magazine, even the very old were not necessarily about to die imminently.  for those under 90, expected years of life lost ranged from 10 to over 30 (depending on decade of age) for those with no conditions, and from 5 to over 25 for those with 3 long term conditions.
    even thinking about nursing home patients, many people in nursing homes are there, not to be 'maintained by the health care system,' but to get basic life care, and presumably have life expectancies over 1 year.

    within a few years, we will have a much better idea about all these things.  the 'extra kick' hypothesis implies that the year after the the pandemic ends should see much lower death rates, while the 'disease killed off viable people' hypothesis implies that we should see only a slight dip (even those with long expected lives have a small chance of dying soon).

    ------------------------------
    Ellen Hertzmark
    ------------------------------



  • 14.  RE: The meaning of excess deaths

    Posted 05-20-2020 20:08
    The data is a time series & one should consider temporal variations. Perhaps there is seasonality in the data or other time correlations.

    ------------------------------
    Jack Lothian
    Senior Survey Methodologist
    Retired
    ------------------------------



  • 15.  RE: The meaning of excess deaths

    Posted 05-21-2020 08:06

    One cannot overstate the implication that the estimating total deaths can have on determining the potential of a coronavirus resurgence. That resurgence may be impacted by the coronavirus spreading among the pockets of people who were less likely to be accessed by the healthcare system.  For example, the NY Times documents the sections in Queens with a high concentration of coronavirus. Many of the likely victims were not even tested because when the paramedics arrived the potential patients had already passed away. Therefore, assuming that this scenario will continue, there are other likely potential victims in these sections of Queens. (Similar concentrations of  hypothetically under-reported coronavirus victims and an analogous concentration of demographics more likely to succumb to the coronavirus may be found in the Bronx.) Nationally, deaths from, in order: heart disease, chronic low respiratory, cerebrovascular, Alzheimer's, diabetes and influenza/pneumonia diseases are more likely concentrated among those >=65 (DHHS/CDC, 2017). Thus, searching for this demographic will help identify a number of underlying conditions vulnerable to the effects of the virus.  A CMS database containing those over 65 relying on electronic equipment can be helpful here. This issue is further compounded by the current dismantling and even harassing of social distance guidance.

    Likewise, other demographic groups, such as African-Americans and Hispanics, who have a disproportionate concentration of these medical conditions, may be similarly vulnerable to life threatening events, such as exposure to the coronavirus. So, given the spatial area concentrations containing populations with these risk factors, there is a need to proactively seek those with coronavirus symptoms.  

    It would be helpful to re-examine the supposed model shortcomings when they predicted many more potential victims. Perhaps, the results from the excess deaths analyses will show that the models were much more right than wrong.



    ------------------------------
    Mark Czarnolewski
    ------------------------------



  • 16.  RE: The meaning of excess deaths

    Posted 05-22-2020 17:43
    ​I hope the excess death models will break out the data by age group and gender and preferably race as well.  I really can't imagine that they wouldn't.  I think there will be much to learn from them.  Eventually, I would hope to be able to review attributed cause of death for these as well.  All in its time.

    I am sure that the CDC will put out a report (or model) in a year or so, but does someone have recommendations for sources in the nearer term?  How soon will Yale put out their results once they revisit things in July?  I would like to believe that there are several groups, NGOs, universities and agencies working on this.  It will be interesting to compare the results.

    ------------------------------
    Raoul Burchette
    Biostatistician
    ------------------------------



  • 17.  RE: The meaning of excess deaths

    Posted 06-14-2020 16:10
      |   view attached
    Timely all-cause death (ACD) counts, series that provide bases for excess death counts, have limitations that require adjustments. ACD counts in the USA come from state mortality databases. Reporting by some states lags that of other states, and states tend to revise counts upward as information about previously unreported deaths comes to light. The graph below shows counts on the horizontal axis and the "as of date", the date of an update of a count for a specific week. The different colors of lines represent series of ACD counts for weeks ending on the date shown in the legend. Data for the USA come from worksheets downloaded from https://data.cdc.gov/NCHS/Provisional-COVID-19-Death-Counts-by-Week-Ending-D/r8kw-7aab on different dates.


    I'd say the graph shows that the counts may double from a report in a week to another report two weeks later. The slope of the curves turns toward vertical as the counts approach a more stable value, but small increases continue. Increasing slopes of the curves in more recent reports reflect, I suppose, slowdowns in reporting deaths in some states.

    I've attached an Excel worksheet with data on the lags. See the concise SAS script that generates the graph below, in case someone has an interest in replicating or extending the visualization exercise:

    libname allCause xlsx "..\DeathsReportingLags.xlsx";

    proc sql;
    create table weeks as
    select * from allCause.weeks
    order by weekend,asofdate ;
    quit;

    proc transpose data=weeks (keep = asofdate weekend allcausedeaths) out=lags;
    ID asofdate ;
    by weekend;
    var allcausedeaths ;
    run;

    title 'Lags in reporting all-cause deaths';
    proc sgplot data=weeks (where=(WeekEnd >= "18apr2020"d));
    series x=allCauseDeaths y=asofdate /
    group=WeekEnd lineattrs=(thickness=5);
    run;
    title;

    Earlier I asked for national ACD data by county. No response as yet .... Timely tracking of excess death "hot spots" during the pandemic will depend not only on disaggregated data, but as well on estimates of local lags in reporting. National counts do not provide enough information for good estimates of regional differences in reporting lags.

    As for the original question about the meaning of excess death models, it seems obvious when you think about the costs and benefits of different interventions aimed at mitigating the impact of the pandemic and its economic backlash, excess deaths measure a real cost of the pandemic to the nation. Any substantial reduction in life expectancy has to be taken into account when balanced against the benefits of opening hair styling salons, tattoo parlors, bars, and other  venues that bring people into close contact. The claim that excess deaths in the pandemic mainly involves persons the medical system is keeping alive has no basis in evidence that I have seen, and it reeks of a "younger generation burden" premise that I have heard. Let evidence speak for itself in these benefit/cost trade-offs.
























    l



    ------------------------------
    Sigurd Hermansen
    ------------------------------

    Attachment(s)

    xlsx
    DeathsReportingLags.xlsx   15 KB 1 version