Compare methods

	Quality-Adjusted Life Years	Abridged Life Table
Field	Health Economics	Social Epidemiology
Family	Process / pipeline	Process / pipeline
Year of origin	1986	1984
Originator	George W. Torrance; Milton C. Weinstein	Chin Long Chiang; Samuel Preston, Patrick Heuveline & Michel Guillot
Type	Utility-weighted survival metric pipeline	Demographic estimation pipeline for mortality and survivorship
Seminal source	Weinstein, M. C., Torrance, G., & McGuire, A. (2009). QALYs: The Basics. Value in Health, 12(Suppl 1), S5-S9.	Chiang, C. L. (1984). The Life Table and Its Applications. Malabar, FL: Robert E. Krieger Publishing. ISBN: 9780898745702
Aliases	QALY Computation, Quality-Adjusted Survival, Utility-Weighted Life Years, QALY Calculation for Cost-Utility Analysis	Abridged Life Table Method, Grouped-Age Life Table, Chiang Life Table, nMx to nqx Life Table
Related	3	3
Summary	The quality-adjusted life year, or QALY, is the standard outcome measure of cost-utility analysis in health economics. It combines length and quality of life into one number by weighting each year a person lives by a utility value reflecting their health-related quality of life during that year, on a scale where one is full health and zero is death. One year in perfect health is one QALY; two years lived at a utility of one half is also one QALY. Because the metric expresses survival and health-related quality of life in a single unit, it lets analysts compare interventions that extend life, improve quality of life, or do both, and it forms the denominator of the incremental cost-effectiveness ratios that health-technology agencies use to decide what to fund. George Torrance set out the methods for measuring the health-state utilities at the heart of the QALY, and Weinstein, Torrance, and McGuire later distilled the concept and its construction for a broad audience.	The abridged life table is the workhorse of demography and population health for summarizing the mortality experience of a population in a single, age-grouped table. Instead of a single-year (complete) life table, it works on broad age intervals — typically <1, 1-4, then five-year groups up to an open-ended oldest interval — which makes it robust when deaths or populations in single years of age are sparse or noisy. The construction propagates a small set of inputs, the age-specific death rates nMx, through a chain of columns: the probability of dying nqx, the survivors lx, the deaths ndx, the person-years lived nLx and Tx, and finally life expectancy ex. Chiang's 1984 treatment supplied the standard estimator and the fraction-of-interval term ax that controls how person-years are allocated within each interval, while Preston, Heuveline and Guillot's 2001 textbook codified the modern pipeline used across demography and epidemiology.