Premature Deaths, Statistical Lives, and Years of Life Lost: Identification, Quantification, and Valuation of Mortality Risks

Abstract

Mortality effects of exposure to air pollution and other environmental hazards are often described by the estimated number of "premature" or "attributable" deaths and the economic value of a reduction in exposure as the product of an estimate of "statistical lives saved" and a "value per statistical life." These terms can be misleading because the number of deaths advanced by exposure cannot be determined from mortality data alone, whether from epidemiology or randomized trials (it is not statistically identified). The fraction of deaths "attributed" to exposure is conventionally derived as the hazard fraction (R -1)/R, where R is the relative risk of mortality between high and low exposure levels. The fraction of deaths advanced by exposure (the "etiologic" fraction) can be substantially larger or smaller: it can be as large as one and as small as 1/e (0.37) times the hazard fraction (if the association is causal and zero otherwise). Recent literature reveals misunderstanding about these concepts. Total life years lost in a population due to exposure can be estimated but cannot be disaggregated by age or cause of death. Economic valuation of a change in exposure-related mortality risk to a population is not affected by inability to know the fraction of deaths that are etiologic. When individuals facing larger or smaller changes in mortality risk cannot be identified, the mean change in population hazard is sufficient for valuation; otherwise, the economic value can depend on the distribution of risk reductions. KEY WORDS: Attributable death; disability-adjusted life year; environmental burden of disease; hazard fraction; premature death; value per statistical life; years of live lost

Health Impacts of Ambient Biomass Smoke in Tasmania, Australia

“…We applied a recommended VSL value to estimate mortality costs, and this method does not consider possible differences by age or health status [57]. It should be noted that VSL is not an objective representation of the monetary value of a human life, but rather represents how much individuals in a population are willing to exchange part of their wealth for changes in their mortality risk [57,58]. Despite the recognized limitations, this monetization method has been widely used to quantify and value the health impacts attributable to air pollution [14,15,53,57,[59][60][61].…”

A Unified Probabilistic Framework for Cancer Risk Management

“…Perhaps the simplest approach for valuing reductions in occupational cancer risk would be to multiply changes in the YLL and YLD by the value per statistical life‐year (VSLY), respectively (Hammitt, 2007). However, this approach would not result in a valid welfare economic measure of cancer burden as it ignores that, across the cohort, some disability‐adjusted life years would be lost sooner and others later in life (Hammitt et al., 2020). To account for temporal aspects, any valuation model needs to be amended with a proper discounting regime.…”

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