DALY (Disability-adjusted life year)

The Disability-Adjusted Life Year (DALY) is the cornerstone metric of the Global Burden of Disease framework, expressing population health loss as the sum of Years of Life Lost from premature mortality (YLL) plus Years Lived with Disability (YLD). One DALY equals one year of healthy life lost. YLL is calculated as the number of deaths multiplied by the standard remaining life expectancy at the age of death; YLD multiplies prevalence of a condition by a disability weight (0 to 1) reflecting severity. Originally developed by Murray and Lopez at Harvard in 1996 in collaboration with WHO and the World Bank, DALYs now drive global health prioritisation. GBD 2019 estimated approximately 2.5 billion DALYs worldwide, with cardiovascular disease, neonatal disorders, and cancers leading the burden.