<P> The disability - adjusted life year is a societal measure of the disease or disability burden in populations . DALYs are calculated by combining measures of life expectancy as well as the adjusted quality of life during a burdensome disease or disability for a population . DALYs are related to the quality - adjusted life year (QALY) measure; however QALYs only measure the benefit with and without medical intervention and therefore do not measure the total burden . Also, QALYs tend to be an individual measure, and not a societal measure . </P> <P> Traditionally, health liabilities were expressed using one measure, the years of life lost (YLL) due to dying early . A medical condition that did not result in dying younger than expected was not counted . The years lost due to disability (YLD) component measures the burden of living with a disease or disability . </P> <P> DALYs are calculated by taking the sum of these two components: </P> <Dl> <Dd> DALY = YLL + YLD </Dd> </Dl>

Why are disabilities first on the disability adjusted life years list