Disability-adjusted life year
Say it: dis-uh-BIL-ih-tee uh-JUS-tid LYFE YEER
A disability-adjusted life year (DALY) equals one year of healthy life lost, counting both early death and time spent living with illness or disability.
Also: DALY, DALYs, disability-adjusted life years
Definition
What is a disability-adjusted life year?
The disability-adjusted life year (DALY) is a summary measure of the burden of disease that puts early death and ill health on a single scale. One DALY stands for one year of full health lost. The DALYs for a condition are the sum of two parts: years of life lost (YLL), which counts for each death the further years a person of that age would normally have lived, and years lived with disability (YLD).
YLD multiplies the time people spend with a condition by a disability weight, a number between 0, meaning full health, and 1, meaning a state as bad as death. A year with mild hearing loss therefore counts for far less than a year with severe depression. Adding DALYs across a population measures the gap between its actual health and an ideal in which everyone lives a long life free of disease.
The measure was introduced in the World Bank's 1993 World Development Report and the first Global Burden of Disease study, and the World Health Organization now uses it to compare diseases and countries. Because it counts disability as well as death, it shows the weight of conditions that seldom kill, such as low back pain and depression, and it helps governments set priorities and judge cost-effectiveness, often as cost per DALY averted.
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- MorbidityMorbidity is the state of having a disease, injury or disability, and also the amount of illness in a population, measured by incidence and prevalence.
- Life expectancyLife expectancy is the average number of further years people of a given age would live if current death rates at each age stayed the same.
- Mortality rateA mortality rate is how often death occurs in a defined population over a set period, usually given as deaths per 1,000 or 100,000 people.
- Public healthPublic health is the science and practice of preventing disease and injury and promoting health across whole communities rather than individual patients.
- Noncommunicable diseaseA noncommunicable disease is a long-lasting illness, such as heart disease, cancer or diabetes, that does not pass from one person to another.
- EpidemiologyEpidemiology is the study of how often diseases and other health events occur in populations, what causes them and how they can be controlled.
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Written for biofideX in plain words, after checking these references:
- WHO Global Health Observatory, indicator metadata: Disability-adjusted life year (DALY) estimates
- Larson (2013), Calculating disability-adjusted-life-years lost (DALYs) in discrete-time, Cost Effectiveness and Resource Allocation
- NCBI MeSH: Disability-Adjusted Life Years
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