5.4 Disability-adjusted life years (DALYs)

DALYs are a quantitative measure of burden of disease that reflects the total amount of good health lost, whether from premature mortality or poor health and disability over a period of time.

DALYs for a health condition can be calculated by adding the healthy years of life lost due to poor health or disability to the years of life lost due to premature mortality. This calculation is DALY = YLD + YLL, where YLD = years lived with disability and YLL = years of life lost.

For the proportion of patients that die, the YLLs lost can typically be calculated by subtracting the life expectancy with a health condition from the normal life expectancy in that country or setting. The YLDs are calculated by multiplying the time spent living with disability by a factor that accounts for the severity of the condition with something called a ‘disability weight’.