Uncertainty Analysis of Quality Adjusted Life Years Lost
Quality-adjusted life years (QALYs) are a measure used to account for the impact of a health state on both quality and quantity of life. It is the product of life expectancy and quality of life changes. Loss of one year of QALY is equivalent to losing a year of quality of life due to premature mortality. Currently, the National Highway Traffic Safety Administration (NHTSA) uses QALY estimate in cost-utility analysis of injury prevention measures.
A variety of “preference-based” instruments have been developed to measure health status or QALY losses. These instruments put preference weights on different health dimensions to reflect the value of social preferences and perceived relative importance of each dimension. The Injury Impairment Index (III) is a preference-based instrument that applies functional losses in six health dimensions to compute QALY losses from injury. Within each dimension in the III there are four levels of severity. Uniquely, the preference weights used in the III are derived from a review of preference weights used in other instruments. The first generation of III preference weights is based on Miller et al.’s (1995) review.
This report updated the Miller et al. (1995) III preference weights using the most recent literature. The variability was analyzed and then applied in sensitivity analysis to examine the resulting range of QALY loss estimates for injury.