The disability-adjusted life year (DALY) is a generic measure of health effect that can be used in cost-effectiveness analysis as an alternative to the quality-adjusted life year (QALY). Originally developed by the World Bank in 1990 DALYs have been adopted by the World Health Organisation (WHO) as a favoured way of comparing overall health and life expectancy in different countries. They are a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability or early death. A DALY represents one year of healthy life, and is usually expressed as DALYs lost compared with theoretical maximum, this being a life with maximum achievable life-expectancy and without disability or disease. In some calculations years of healthy life are age-weighted, resulting in disability in younger years having a higher overall impact on overall DALY scores. Based on the ‘person trade-off’ technique, disability weights for (seven levels of) conditions have been determined by a panel of experts, and aggregate DALYs lost (globally and by country) calculated for a wide range of conditions. DALYs differ from QALYs in that the weights are not based on population surveys (of references for health states) and the two components (reduced survival and increased disability) are added and not multiplied. In Western countries psychiatric conditions (generating large amounts of time spent with disability, but not reduced survival) are prominent as leading causes of lost DALYs.

How to cite: Disability-Adjusted Life-Years (DALYs) [online]. (2016). York; York Health Economics Consortium; 2016. https://www.yhec.co.uk/glossary/disability-adjusted-life-years-dalys/

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