Comparative Quantification of Mortality and Burden of Disease Attributable to Selected Risk Factors

Excerpt

To permit the assessment of risk factors in a unified framework while acknowledging characteristics specific to individual risk factors, the Comparative Risk Assessment (CRA) project initiated a systematic evaluation of the changes in population health that would result from modifying the population distribution of exposure to a risk factor or to a group of risk factors (Murray and others 2003; Murray and Lopez 1999; Ezzati and others 2004). In particular, the CRA framework

1. compares the burden of disease due to the observed distribution of exposure in a population with the burden from an alternative distribution consistently defined across risk factors;

2. considers multiple stages in the causal network of multiple risk factors and disease outcomes to allow inferences about combinations of risk factors for which epidemiological studies have not been conducted, including the joint effects of changes in multiple risk factors;

3. converts the burden of disease and injury into a summary measure of population health that permits comparing fatal and nonfatal outcomes while also taking severity and duration into account (the summary measure used in this chapter is the disability-adjusted life year [DALY], whose definition and calculation are described in chapter 3).

Therefore, even though CRA is similar to other risk assessment exercises in the sense that it applies knowledge about the hazardous effects of risk factors from epidemiological research to data on exposure in the broader population, it creates conceptual and methodological consistency in measuring the impacts of various risk factors on population health. Furthermore, we have attempted to use consistent and comparable criteria for evaluating the scientific evidence on prevalence, causality, and magnitude of hazardous effects across risk factors. As a result, the unified framework for describing population exposure to risk factors and their consequences for population health is an important step in linking the growing interest in the causal determinants of health across a variety of disciplines from natural, physical, and medical sciences to the social sciences and humanities.