QALYs vs DALYs vs LYs gained: What are the differences, and what difference do they make for health care priority setting?

QALYs, DALYs and life years gained are all common outcome measures in economic evaluations of health interventions. While the latter is a pure measure of mortality, QALYs and DALYs are measures that combine mortality with morbidity in single numerical units, an exercise involving trade-offs between quantity for quality of health. Some authors have argued that mortality and morbidity are totally different dimensions, and combining them into a single numerical unit is nonsensious. Others have argued that the exercise is necessary in order to convert principles for resource allocation to criteria that can be used in a consistent manner. This paper has a two-fold objective, namely to discuss the differences between these health measures, and to explore what difference they are likely to make for health care priority setting in sub-Saharan Africa.