Measuring health in a vacuum: examining the disability weight of the DALY.

The Disability Adjusted Life Year (DALY) is a widely used summary measure of population health combining years of life lost due to mortality and years of healthy life lost due to disability. A feature of the DALY is that, in the assessment of morbidity, each health condition is associated with a disability weight. The disability weight lies on a scale between 0 (indicating the health condition is equivalent to full health) and 1 (indicating the health condition is equivalent to death). The disability weight associated with each health condition is currently fixed across all social, cultural and environmental contexts. Thus blindness in the United Kingdom has the same disability weight as blindness in Niger in spite of structural interventions in the UK that make the disability less severe than in Niger. Although the fixed disability weight is defended on grounds that it supports a strongly egalitarian flavour in the DALY, we argue that the lack of consideration of realistic contexts results in a measure that will underestimate the burden associated with morbidity in disadvantaged populations and overestimate the burden in advantaged populations. There is, consequently, a loss of information on possible non-clinical points of intervention. Disaggregated estimates of the burden of disease such as those in the World Health Report 2000 should be interpreted with caution.

The DALY, context and the determinants of the severity of disease: an exploratory comparison of paraplegia in Australia and Cameroon.

This paper summarises the findings of an empirical investigation of some of the technical and social assumptions on which the disability adjusted life year (DALY) is based. The objectives of the study were to examine the notion that the burden of disease is broadly similar without regard to country, environment, gender or socio-economic status and to develop detailed descriptions of the experiences of the burden of disease as they related to these contextual factors. The study was a multi-factorial exploratory study employing qualitative and quantitative techniques to obtain data on the effects of country (development), environment (urban versus rural), gender and socio-economic status on people with paraplegia. The data provided an extensive and detailed compilation of context rich descriptions of living with paraplegia. Striking features of the data were the differences between countries with respect to the impact of the health conditions on functioning and highlight a context in which paraplegia of like clinical severity can be fatal in one environment and not in another. While there has been some focus on the control of social determinants of disease, there has been little work on the social determinants of the severity of disease. The underlying assumptions of the DALY, which ignore context in the assessment of the burden of disease, risk exacerbating inequalities by undervaluing the burden of disease in less-developed countries. There is a need to continue to subject the development of indicators to rigorous debate to determine a balance between the assumption of a global "average social milieu" and the treatment of each individual as belonging to their own context in the assessment of population health in order for indicators to be meaningful cross-culturally.