Contribute Try STAT+ Today

The Centers for Disease Control and Prevention made headlines last week when it announced that Covid-19 had reduced the average life expectancy of Americans in 2020 by a full year. The news seemed to starkly illustrate the devastation wrought by our nation’s worst public health crisis in 100 years.

But there was a problem. The pandemic’s appalling toll could not have reduced life span by nearly that much. My own estimate is that when Covid-19’s ravages in 2020 are averaged across the country’s entire population, we each lost about five days of life.

The CDC’s mistake? It calculated life expectancy using an assumption that is assuredly wrong, which yielded a statistic that was certain to be misunderstood. That’s exactly the type of misstep the agency can’t afford to make. Not now, not after former President Trump’s relentless attacks on its credibility. Not after his advisers were caught altering and editing the agency’s monthly reports to downplay the pandemic.

advertisement

To review: The CDC reported that life expectancy in the U.S. declined by one year in 2020. People understood this to mean that Covid-19 had shaved off a year from how long each of us will live on average. That is, after all, how people tend to think of life expectancy. The New York Times characterized the report as “the first full picture of the pandemic’s effect on American expected life spans.”

But wait. Analysts estimate that, on average, a death from Covid-19 robs its victim of around 12 years of life. Approximately 400,000 Americans died Covid-19 in 2020, meaning about 4.8 million years of life collectively vanished. Spread that ghastly number across the U.S. population of 330 million and it comes out to 0.014 years of life lost per person. That’s 5.3 days. There were other excess deaths in 2020, so maybe the answer is seven days lost per person.

advertisement

No matter how you look at it, the result is a far cry from what the CDC announced.

It’s not that the agency made a math mistake. I checked the calculations myself, and even went over them with one of the CDC analysts. The error was more problematic in my view: The CDC relied on an assumption it had to know was wrong.

The CDC’s life expectancy calculations are, in fact, life expectancy projections (the technical term for the measure is period life expectancy). The calculation is based on a crucial assumption: that for the year you are studying (2019 compared to 2020 in this case) the risk of death, in every age group, will stay as it was in that year for everyone born during it.

So to project the life expectancy of people born in 2020, the CDC assumed that newborns will face the risk of dying that newborns did in 2020. Then when they turn 1, they face the risk of dying that 1-year-olds did in 2020. Then on to them being 2 years old, and so on.

Locking people into 2020 for their entire life spans, from birth to death, may sound like the plot of a dystopian reboot of “Groundhog Day.” But that’s the calculation. The results: The CDC’s report boils down to a finding that bears no relation to any realistic scenario. Running the 2020 gauntlet for an entire life results in living one year less on average than running that same gauntlet in 2019.

Don’t blame the method. It’s a standard one that over time has been a highly useful way of understanding how our efforts in public health have succeeded or fallen short. Because it is a projection, it can (and should) serve as an early warning of how people in our society will do in the future if we do nothing different from today.

But in this case, the CDC should assume, as do we all, that Covid-19 will cause an increase in mortality for only a brief period relative to the span of a normal lifetime. If you assume the Covid-19 risk of 2020 carries forward unabated, you will overstate the life expectancy declines it causes. It’s not like I am the first person to notice this problem. Researchers have regularly demonstrated that life expectancy projections are overly sensitive to evanescent events like pandemics and wars, resulting in considerably overestimated declines.

And yet the CDC published a result that, if anything, would convey to the public an exaggerated toll that Covid-19 took on longevity in 2020. That’s a problem.

Please don’t misunderstand: I have no desire to play down this horrific pandemic. The U.S. recently surpassed a half-million deaths, the highest number of deaths of any country. Instead, I mean to emphasize that the CDC must remain the world’s gold standard public health agency, and that means working tirelessly to get both its facts and its messages right.

The agency won’t always succeed. But after four years of an administration that claimed infallibility, even as the pile of errors reached staggering heights, we should hold this administration’s CDC to the highest possible standard.

I have been wondering if the CDC should withdraw this report, explaining that it erred by disseminating a finding that was bound to be misunderstood. Yes, Covid-19 deniers will try to score cheap political points for a day or two. But at least for me, I don’t need an agency that is flawless, but one that is forthright.

Peter B. Bach is a physician at Memorial Sloan Kettering Cancer Center, where he directs the Center for Health Policy and Outcomes.

  • C19 hasn’t reduced the life span of anyone other than those who happened to die “from” it not with it.

  • The nice thing about Dr. Bach’s article is that his calculations can be reproduced. There are two side questions, one of which another commentator has touched upon: Has the US had 500,000+ deaths because of or with COVID19? (Analogy: it is said that many of us men will die with prostate cancer, but not of the disease.) And, are we confident that there are no other countries (e.g., China) which have more deaths than our country?

  • This article is a complete misunderstanding. The one year difference was answering a simple question: Do people die with COVID-19, or do they die from COVID-19? To answer this question you should consider the death rate by year, and life expectancy at birth is nothing but an index for this. Any time I teach this notion, I made a point to start that, obviously, life expectancy as published doesn’t say anything about the life expectancy of any stratum. If the critic was relevant, then any demographic table of life expectancy was meaningless, and the effect of the COVID pandemic and the opioid crises on it was irrelevant. However, it is the best indicator.

  • In other words, the CDC made a projection with the assumption that the pandemic is eternal from 2020 forward. That is obviously wrong. Even if viral variants and recombinants make the pandemic eternal, one cannot assume that the death rate will always remain the same. It could fade into the background as people gain immunity to various strains, or it could even increase dramatically if a new, vaccine escaping, super virulent strain sweeps the country.

  • Oh my, you fundamentally misunderstand what life expectancy is. CDC’s statistic is accurate and correctly calculated and can be compared to other estimates of life expectancy calculated in this very normal way – it relates to a synthetic cohort representing a period of time, just like it always has! Refer to any introductory demography methods text to help understand what life expectancy is, e.g. Preston et al. ‘Demography:Measuring and Modeling Population Processes’ – https://www.amazon.com/dp/1557864519/ref=cm_sw_r_oth_api_glt_fabc_NM48176VH3PWJZKGJS7D.

    • Normally I would say Thanks For the Link, and go follow it to try to understand a complex process, rather than share my ignorance any further – but the link is to a science text which costs just under $100, and you are not giving me any indication the author of this article fundamentally misunderstands what Life Expectancy is – in fact, he agrees with the calculations which were quoted in the media, he says, having done them himself to check.
      So, to cut to what I think is the chase here, some questions:

      1. Is if true people born in the US in 2020 can really expect to live a year less, if they are white, and 2.7 years less, if they are black, due to SARS CoV2?
      (closely related, can those of all ages expect an average loss of 1 year if white, 2.7 if black? )

      2. Is it useful or even responsible for our main Federal agency dealing with such problems to deliberately publicize claims which are highly misleading? I realize we have very poor education in public schools, such that a very large number of Americans are illiterate regarding science, but I do not blame John Q. Public for not understanding what “Life Expectancy” Is. I think John Q. would have the reasonable belief, if you took the study author to a maternity ward, the author would say, “Yes, on average, these kids will live one year less, that is our best possible guess” and from what I understand, absolutely no one at CDC actually believes that.

  • I have to say this article makes me feel good. I had posted in response to the original report of a one year loss in life expectancy that there was something terribly wrong with the number – and calculated about the same average loss of life as this author.

    I am a total laymen without much education, but it was clear the average loss was a tiny fraction -and also clear you could only get close to a one year loss of life by assuming the carnage of 2020 would be repeated for many, many years.

    I will have to go back now to try to read and understand this article, but, unless this author is very badly mistaken, this points to a problem with media – even very good media – the CDC report should have been reported as news – but critically analyzed in the same reports. We seem to be getting dumber, and maybe part of the reason is bad reporting.

  • This piece is offensively disingenuous. This is a man whose entire job is justifying the sky-high prices Big Pharma charges for cancer treatments – which are bankrupting the health system. STAT’s limited disclosure of his bias demands removal of this piece – it’s not opinion, it’s propaganda. As Bach admits, he “received speaking fees from pharmaceutical companies, PBMs, insurers and trade associations.” He is an outspoken opponent of drug pricing limitations, whose word cannot be trusted on any matter relating to public health. Do better, STAT.

    • But is he wrong about this “one year loss in life expectancy”? One in about 500 people in the US is going to die before the vaccine stops the original type-it could be double that, God Forbid, if the variants are a brand new epidemic -but how does 1 in 250 people dying over the course of two years reduce life expectancy by one year for the other 499? or 249?

    • None of this has anything whatsoever to do with the content of his article. His alleged bias is completely unrelated to the matter at hand. There is no reason for STAT to disclose his alleged bias, as it is completely immaterial. You yourself make the logical fallacy of an ad hominem attack.

    • Quite telling that you didn’t comment on the ideas, but launched an irrelevant ad hominem.

  • Thank you for your clarifying comments on the CDC life expectancy report. Unfortunately, it is this type of communication from the CDC and through the media that make people skeptical.

    I would be interested in your thoughts on the assumption underlying all the calculations. That is the number of 12 for years of life lost. Looking at February 2021 cumulative numbers, about 32% of C-19 deaths are people age 85 and older. Another 28% of deaths are people age 75 through 84, with 22% of deaths in the 65 through 74 year age range. In total, age 65 and older C-19 deaths are 81% of all C-19 deaths to mid-February 2021.

    • I agree. I have heard that number and it seems too high as well. Obviously, the small percent of people dying who are 30-40 and under will push up the average. But, if 40% are in LTC, these are not people who were – as much as I wish it were true – living 5-10 more years if COVID never occurred and many would have died in 2020 either way.

      I also think it doesn’t – and probably can’t – take into account the general health of the population. A healthy 40 year old is likely to live 40-50 more years whereas someone who is really prone to adverse outcomes from COVID would likely live 20-30 or less.

      The 1 year loss of life is such an obvious math error it is amazing that the CDC published it.

  • Yes – it’s hard to believe that someone could actually release such a report. This flunks the reasonableness test at its most basic level. Based on all the information we have, COVID is a one-off event. The author is correct – the should publicly admit its mistake and withdraw the report…..but it won’t.

    • Even if it isn’t a one-off event, you can’t predict its future course. It depends on too many unknown unknowns. Extrapolating 2020 to the indefinite future can’t possibly be valid under any circumstances.

Comments are closed.