Shifting the goalpost—normative survivorship goals in health gap measures

Health gap measures, such as the DALY, are a quantification of the gap between the current health status in a population and a stated goal for population health. This goal can be understood as an ideal situation in which everyone in a population lives into old age free of disease. Health gaps are the addition of time lost due to premature mortality, as measured against the normative survivorship goal and time spent in states of less than full health, weighted for severity. Assuming a stable population, the health gap is shown in Figure 1 as area C, between the survivorship curve and the normative survivorship goal, plus area B indicating the proportion of time lived in less than full health weighted for severity (Murray et al. 2000). This paper examines the mortality component of health gaps and the desirability of the current methods used in burden of disease studies.