Years of life lost estimates and averages

Different averages tell different stories.

How many potential years of life do people dying of Covid-19 lose? That is a prominent question in the pandemic. It is another way of showing mortal impacts, giving greater weight to younger deaths.

Years of life lost

What does ‘years of potential life lost’ mean? There are different definitions. One definition compares a person’s actual age at death with life expectancy at that age. The difference is then the potential years of life lost. It is a difference between reality and expectation. Such analyses could also account for co-morbidities.

Another definition compares actual death ages with a reference age. If a person dies older than the reference age, their potential years of life lost is set to zero. Both definitions measure premature mortality using different methods.

Another methodological issue arises when analysts summarise the distribution of potential years lost. This is often the mean average:

Using the standard WHO life tables, YLL per COVID-19 death was 14 for men and 12 for women. After adjustment for number and type of LTCs, the mean YLL was slightly lower, but remained high (11.6 and 9.4 years for men and women, respectively).

Distributions and averages

A Wellcome Open Research study models years of life lost for Covid-19 deaths in Italy. These…