Attribution of disease burden to risk factors

The burden of disease attributable to important risk factors is calculated from:

• a database on the prevalence of exposure to the risk factor by age and sex, year and region
• estimates of the relative risk associated with each specific disease obtained from meta-analyses of the studies of that relative risk
• assumptions about minimum risk exposure. In some instances, this is zero (e.g. tobacco smoking), but in others (e.g. body mass index) it is the value that is thought to be theoretically achievable at a population level which is associated with the smallest absolute risk.

Estimates were produced for 43 risk factors for disease. For example, the risk factors included physical inactivity, unimproved sanitation, suboptimal breastfeeding, high blood pressure, and occupational exposure to carcinogens, and also a cluster of 14 distinct dietary risk factors. A few of these risk factors were further sub-divided into more specific risks (such as non-exclusive and discontinued breastfeeding).