The Devils in the DALY: Prevailing Evaluative Assumptions

Abstract

In recent years, it has become commonplace among the Global Burden of Disease (GBD) study authors to regard the disability-adjusted life year (DALY) primarily as a descriptive health metric. During the first phase of the GBD (1990-1996), it was widely acknowledged that the DALY had built-in evaluative assumptions. However, from the publication of the 2010 GBD and onwards, two central evaluative practices-time discounting and age-weighting-have been omitted from the DALY model. After this substantial revision, the emerging view now appears to be that the DALY is primarily a descriptive measure. Our aim in this article is to argue that the DALY, despite changes, remains largely evaluative. Our analysis focuses on the understanding of the DALY by comparing the DALY as a measure of disease burden in the two most significant phases of GBD publications, from their beginning (1990-1996) to the most recent releases (2010-2017). We identify numerous assumptions underlying the DALY and group them as descriptive or evaluative. We conclude that while the DALY model arguably has become more descriptive, it remains, by necessity, largely evaluative.