Understanding the contribution of risk factors to disease burden has motivated several comparative studies in the past few decades. The seminal work of Doll and Peto1 provided a comparative assessment of the importance of different exposures, particularly tobacco smoking, in causing cancer. Peto and colleagues2 subsequently estimated the effects of tobacco smoking on mortality in developed countries since 1950. Although these risk factor-specific or cause-specific analyses are useful for policy, a more comprehensive global assessment of burden of disease attributable to risk factors can strengthen the basis for action to reduce disease burden and promote health. The Global Burden of Disease Study (GBD) 1990 provided the first global and regional comparative assessment of mortality and disability adjusted life-years (DALYs) attributable to ten major risk factors.3 However, different epidemiological traditions for different risks limited the comparability of the results. Subsequently, Murray and Lopez4 proposed a framework for global comparative risk assessment, which laid the basis for assessment of 26 risks in 2000.5–7 Since this work, WHO has provided estimates for some risks by the same methods but with updated exposures and
