The CRA conceptual framework was developed by Murray and Lopez,13 who established a causal web of hierarchically organised risks or causes that contribute to health outcomes (method appendix; appendix 1 p 432), which allows quantification of risks or causes at any level in the framework. In GBD 2016, as in previous iterations of GBD, we evaluated a set of behavioural, environmental, and occupational, and metabolic risks, where risk-outcome pairs were included based on evidence rules (appendix 1 p 344). These risks were organised into five hierarchical levels as described in appendix 1 (p 374). At Level 0, the GBD 2016 provides estimates for all risk factors combined, at Level 1 the GBD 2016 provides estimates for three groups: environmental and occupational, metabolic, and behavioral risk factors. At Level 2, there are 17 risks, at Level 3 there are 50 risks, and at Level 4 there are 67 risks, for a total of 84 risks or clusters of risks. To date, we have not quantified the contribution of other classes of risk factors (appendix 1 p 376); however, using an analysis
