The Language of Value: Disability-Adjusted Life Years (DALYs) in Global Health and Thick Evaluative Concepts

The disability-adjusted life year (DALY) is a measure that has a ubiquitous presence in academic global health (Solberg et al. 2020). The aim of the DALY is not simply to be another method of disease surveillance, but to help quantify disease burden in order to assist policymakers with resource allocation (Voigt et al. 2014). Because it is a measure that quantifies burden, it goes beyond mere epidemiological description. Though the creators of the DALY initially acknowledged its value-laden nature, gradual changes have been made to try to make it a purely descriptive measure. Within two decades, the DALY has gone from being described as a measure of burden “based on explicit and transparent value choices” (Murray and Lopez, 1996) to “a major step toward a replicable scientific approach to global descriptive epidemiology” (Murray et al., 2012). Although ‘thick evaluative concepts’ have been discussed in philosophy since their explicit formulation by Bernard Williams (Williams 1985), it has not entered the collective awareness of academic medicine. The concept, in brief, distinguishes between purely descriptive terms (such as ‘square’) and purely evaluative terms (such as ‘bad’). A thick evaluative concept is one that contains both evaluative and non-evaluative descriptions. The authors argue that “burden” and “disability”—both intimately tied into the DALY—are thick evaluative concepts, and that the DALY is therefore innately evaluative. The significance of this is that the assumptions made by DALYs, such as the underlying philosophical model of disability, should be explicitly examined in order to best implement this measure.

desmond Jumbam, MSGH – Director, Policy & Advocacy, Policy & Advocacy, Operation Smile; Ruben Ayala, MD, MSc – Chief Policy and Advocacy Officer, Policy & Advocacy, Operation Smile