life expectancy in years =
= 1 / (average annual mortality rate)
and
average annual mortality rate =
= 1 / (life expectancy in years)
where:
• The life expectancy can be determined for a person from actuarial tables, taking account the person's current age, gender and race.
If an intervention or disease changes the average annual mortality rate,
life expectancy with intervention or disease =
= 1 / ((average annual mortality rate) + ((factor) * (change in annual mortality due to intervention or disease)))
increase in life expectancy from an intervention or disease =
= (life expectancy with intervention or disease) – (life expectancy without intervention or disease)
where:
• factor = 1 if it increases mortality and (-1) if it decreases mortality
If actuarial data is not available, life expectancy can be estimated from the following equation, but gender and race effects are ignored (page 887, Beck):
life expectancy in years for a person 20 – 70 years of age =
= (69.5 – (0.80 * (age in years))
life expectancy in years for a person > 70 years of age =
= (51.9 – (0.55 * (age in years))
