Sociology professor Patrick Heuveline devised the metric, called the mean unfulfilled lifespan, to assess the impact of temporary “shocks” like the novel coronavirus on average length of life. To date, the pandemic has claimed the lives of more than 4.2 million people worldwide.
The tool allows demographers to conduct fine-grained analyses in specific regions over various periods of time, offering a new and more dynamic way of gauging how different areas of the country and the world experience decreases in lifespans over the course of the pandemic, Heuveline said.
Heuveline’s analysis, published online in the open-access journal PLOS One, suggests, for example, that as COVID-19 peaked in New Jersey in mid-April 2020, the average lifespan in the state plummeted by almost nine years, the most dramatic example from the U.S.
Demographers typically calculate lifespan using a metric known as period life expectancy at birth, or PLEB, which is the average number of years a person born at a certain time would be expected to live if future death rates remained at present levels. When researchers factor in the impacts of a given cause of death – a steady increase in heart attacks or car accidents, for instance – they see how these factors can reduce PLEB.
However, calculating changes to life expectancy in this way cannot adequately capture the effect of large, temporary shocks like natural disasters or the COVID-19 pandemic, in which mortality conditions are rapidly shifting, Heuveline said.
To more clearly illustrate the impact of such phenomena, Heuveline’s mean unfulfilled lifespan measures the difference between the average age at death of individuals who died within a given time frame and the average age these people would have been expected to reach had there not been a temporary shock.
“As did a few other demographers, I initially tried to convey the mortality impact of COVID-19 by assessing how much life expectancies would decline during the pandemic,” he said. “When mortality conditions are continuously changing, however, life expectancies are hard to interpret, and I wanted to provide a more intuitive indicator of that mortality impact.”
Heuveline demonstrated the mean unfulfilled lifespan by applying it to COVID-19 mortality data from regions with similarly sized populations, including New Jersey, Mexico City, Lombardy in Italy, and Lima, Peru.
He compared decreases in life expectancy by calendar quarter (from March 31, 2020 to March 31, 2021) and using rolling seven-day windows (from March 15 to June 15, 2020). The latter analysis suggested that the mean unfulfilled lifespan peaked at 8.91 years in New Jersey, 6.24 years in in Mexico City, 6.43 years in Lombardy and 2.67 in Lima.
In addition, his study found that during the month of April 2020, the mean unfulfilled lifespan may have reached 12.7 years in the Guayas province of Ecuador.
Heuveline noted that uncertainties in calculating mean unfulfilled lifespan may arise from potential differences between deaths related to temporary shocks like the pandemic and actual or excess deaths – differences that, when accounted for, may push the peak unfulfilled lifespan figures seen in the study even higher. His analysis demonstrates how these issues can be factored into calculations.
Heuveline said he hopes the new metric will eventually be applied broadly as researchers seek to better understand the impact of epidemics, natural disasters and even violence on life expectancy.
Between 2010 and 2018, the gap in life expectancy between the US and the peer country average increased from 1.88 years (78.66 v 80.54 years, respectively) to 3.05 years (78.74 v 81.78 years). Between 2018 and 2020, life expectancy in the US decreased by 1.87 years (to 76.87 years), 8.5 times the average decrease in peer countries (0.22 years), widening the gap to 4.69 years. Life expectancy in the US decreased disproportionately among racial and ethnic minority groups between 2018 and 2020, declining by 3.88, 3.25, and 1.36 years in Hispanic, non-Hispanic Black, and non-Hispanic White populations, respectively.
In Hispanic and non-Hispanic Black populations, reductions in life expectancy were 18 and 15 times the average in peer countries, respectively. Progress since 2010 in reducing the gap in life expectancy in the US between Black and White people was erased in 2018-20; life expectancy in Black men reached its lowest level since 1998 (67.73 years), and the longstanding Hispanic life expectancy advantage almost disappeared.
Meaning of life expectancy during a pandemic
Life expectancy is a widely used statistic for summarizing a population’s mortality rates at a given time.2 It reflects how long a group of people can expect to live were they to experience at each age the prevailing age specific mortality rates of that year.3 Estimates of life expectancy are sometimes misunderstood. We cannot know the future age specific mortality rates for people born or living today, but we do know the current rates. Computing life expectancy (at birth, or at ages 25 or 65) based on these rates is valuable for understanding and comparing a country’s mortality profile over time or across places at a given point in time. Estimates of life expectancy during the covid-19 pandemic, such as those reported here, can help clarify which people or places were most affected, but they do not predict how long a group of people will live. This study estimated life expectancy for 2020. Life expectancy for 2021 and subsequent years, and how quickly life expectancy will rebound, cannot be calculated until data for these years become available. Although life expectancy is expected to recover in time to levels before the pandemic, past pandemics have shown that survivors can be left with lifelong consequences, depending on their age and other socioeconomic circumstances.4
The effect of the pandemic on life expectancy extends beyond deaths attributed to covid-19.8 Studies have found an even larger number of excess deaths during the pandemic, inflated by undocumented deaths from covid-19 and by deaths from non-covid-19 causes resulting from disruptions by the pandemic (eg, reduced access to healthcare, economic pressures, and mental health crises).9101112
Some racial and ethnic populations and age groups have been disproportionately affected.131415 Research on how the pandemic has affected life expectancy is only just emerging.1617 Few studies have examined reductions in 2020 life expectancy across racial and ethnic groups, and none has compared the decline in the US with other countries.
reference link :https://www.bmj.com/content/373/bmj.n1343
More information: Patrick Heuveline et al, The Mean Unfulfilled Lifespan (MUL): A new indicator of the impact of mortality shocks on the individual lifespan, with application to mortality reversals induced by COVID-19, PLOS ONE (2021). DOI: 10.1371/journal.pone.0254925