Age Analysis

Massachusetts Covid Breakdown by Age Part V: Cumulative Death Rates

This post builds on the previous post to develop a better understanding of how covid has impacted death rates by age over time in Massachusetts.  As I’ve already commented ad nauseam, the state’s reporting of cases and deaths makes it extremely difficult to pull this information together.  This, coupled with the change from emphasizing individual-based positivity rates to test-based positivity rates makes me wonder if the state is deliberately obfuscating information to paint a rosier picture or to make it difficult to perform useful analysis. For example, Figure 1 shows the cumulative covid death rate by age over time.



This means that over 2% of seniors 80 and over in Massachusetts have died from or with Covid, regardless of whether they were living in long-term care, assisted living, or independently. But some have made the argument “they were going to die soon anyway”.  Aside from its callousness, is there any truth to this statement?  Table 1 sheds some light on this.


Table 1:  Estimated Covid Mortality Rate Increases in Massachusetts
Rates are Per 100,000
Statistic 20 to 39 Inclusive 40 to 59 Inclusive  60 to 79 Inclusive 80 and Over
Cumulative Covid Death Rate to October 10 1.8 25.4 235.3 2,043.8
Estimated Weekly Covid Death Rate Run Rate 0.0 0.4 2.5 20.4
Extrapolated Annual Covid Death Rate 2.5 33.8 292.2 2,514.1
2017  US Mortality Table Annual Death Rate 133.6 433.0 1,975.4 10,080.4
Percentage Death Rate Ratio 1.9% 7.8% 14.8% 24.9%


Table 1 requires explanation.  I’ve dropped ages under 20 from the table as there has been only one reported death in Massachusetts from covid in that age group. The first line is just the end point of the lines for each age cohort from Figure 1, converted from percentages to rates per 100,000.  For the 80 and over age cohort, for example, it shows the 2% figure for deaths.

The second line is an estimate of ongoing weekly date rates for each age cohort, based on the average number of weekly deaths since August 1st.  This assumes that deaths will continue at these levels – but rates could increase if the pandemic worsens in Massachusetts (there are signs of that since Labor Day), or decrease if treatment protocols become more effective or cases become less severe.  Using this average implies, for example, that 2.5 people per 100,000 between 60 and 79 will die each week from covid in Massachusetts going forward (this is about 32 people total). The third line uses the run rate from the second line to extrapolate the current death rates to a full year (it assumes 23 more weeks). This implies that about 0.3% of people 60 to 79 will have died from covid over one year.

The fourth line is the baseline mortality rate for each age cohort, based on the latest available mortality table for the US.  About 10% of people 80 and over in the US died from all causes in 2017, as did almost 2% of people from 60 to 79.  People in Massachusetts have a higher life expectancy than those in the US, so these age-specific death rates for the state might be somewhat, but not significantly, lower.  Finally, the last, and most important line, is the ratio of the estimated covid death rate in Massachusetts for one year to the total US death rate in 2017.

This emphatically does not mean that excess mortality from covid is close to 25% for those 80 and older, for example.  It certainly is true that some people in that age group who died from covid would have died anyway over the year – covid just hastened their death.  But that is certainly not true for all people 80 and over.  That applies to younger people as well (but the percentage of younger people who died prematurely from covid is certainly much higher). 

These ratios strike me as quite high for people 40 and older.  I was most surprised by the almost 8% ratio for 40 to 59 year old people, who are generally quite healthy, and have a baseline mortality rate of less then one-half of one percent.  For the most part, this age group has been overlooked in the reporting, which tends to focus on seniors or young adults.  In this cohort, it is more difficult to make the case that these covid deaths would have been likely to occur anyway.

A word on excess mortality, which is just the increase or decrease in all-cause mortality over some period compared to a baseline. This is a much better measure of the the overall impact of covid on death rates, as it includes second order effects of the pandemic.  These second order effects cut both ways.  Deaths almost certainly increased because medical appointments and procedures were delayed when hospital were overwhelmed with covid patients and shut down most non-covid care.  In contrast, deaths from some non-medical causes may have decreased because of less societal activity, including travel. But they may have increased as well, with higher suicide rates and more domestic violence. 

One more point.  I am focusing on deaths to explore the seriousness of covid for several reasons.  First, this is where much of the media and popular attention has focused.  Second, I think the hospitalization data by age group in Massachusetts is unreliable. I am very aware that deaths do not tell the whole story, as many people become ill from covid and partially recover but have long-lasting health issues (the so-called “long haulers”).  But at this point, there is little hard data detailing their issues.

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