Cross-national research on diseases and their putative risk factors has long been acknowledged as extremely difficult [7,8]. The creation of an international classification of causes of death advanced this line of inquiry [9], and was followed by the developments of international classifications and measurement approaches for chronic conditions, including mental disorders [10]. Historically, cross-national comparisons for alcohol and tobacco were undertaken using correlation studies of nation-level consumption (e.g., taxation data) plotted in relation to pertinent causes of death (e.g., liver cirrhosis, lung cancer). There is continuing uncertainty, however, about the comparability of death certification practices across countries, and for illegal drugs particularly, official statistics are considered unreliable in many countries [11].
