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02/14/2012

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Will

Point of clarification: does this mean death @50 y/o increase DALYs by approximately 30 (as in 30 years short of life expectancy)?

Also, how do DALYs apply once someone has passed their life expectancy? Would someone dying at 90 have an increase in DALYs or not?

Paul Kelleher

Hi Will,

Using 80 years as the normative standard for life expectancy, death at 50 would generate 30 DALYs (other DALYs may have been generated while this person was alive; 30 is just the number created *by death* itself).--- DALYs use "disability weights" (contrast this with QALYs' "utility weights"). To get the number of DALYs in a life, you multiply the number of years lived in a given state of illness or disability by the disability weight assigned to that state of illness/disability. You do that for all periods of one's life (perhaps lived in different degrees of illness/disability), and all up all those numbers. Finally you add to that sum this number: [80 minus one's age at death]. This gives you total DALYs in a life.

Your second question is a good one. Remember, DALYs are years of healthy life lost. If I lived in full health up to 90 and then died, then I lived 90 healthy life years. But I can also live 90 healthy life years if I live to 100, as long as some of my years were lived in less than full health. The time spent in less than full health did not cut into my longevity, but it would've cut into my quality-of-life, and the metric of healthy life years takes this into account. So your question about someone who dies at 90 cannot be answered without knowing what this person's quality-of-life was. That said, if the normative standard for longevity is set at 80 years, and someone lives 85 years that, in light of their quality, generate 80 *healthy* life years, then I believe that no DALYs are generated by ill healthy this person might suffer after turning 85 years old.

I admit that there may be more to answering this second question than I personally know about.

julian

Life expectancies are defined at every age, so 80 is only the life expectancy at birth (e.g. in Japan). DALYs are normed against a full life table. At age 50, remaining life expectancy is (say) 34 years, not 30. At age 80, it is (say) 6 years. But it is always positive, so there are always DALYs on the table.

A quick note from my father (the Jamison in the post): "Phrasing the benefit as averting something definitely sows confusion. It may be useful to pass on that assessment of disease burden, ie the GBD, was a concept created at the World Bank and contracted by the Bank to WHO and Harvard to implement under the joint leadership of Alan Lopez and Chris Murray." He modestly leaves out that he (as noted in Paul's post) is the lead for the Disease Control Priorities Project.

Paul Kelleher

Thanks for the comment, Julian.

I actually didn't know (and didn't say in the post) that your father is the lead for DCPP. I hadn't investigated enough to know who was involved with DCPP. I just found that document via google and thought it a good contrast to the way your dad puts things in his book.

Thanks again.

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