The studies included in the meta-analysis were selected from PubMed and from the database of Chinese Academic Journals with keywords 'alcohol dehydrogenase', 'ADH3', 'ADH1C', 'association', 'associated', 'drug’, 'substance', 'alcoholism’, 'alcohol’, 'alcoholics', 'heroin’, 'cocaine’, 'opiate', 'opioid', and 'methamphetamine'. All references cited in these studies and in published reviews were examined in order to identify additional works not indexed by the databases. The analyzed studies cover all identified English and Chinese publications up to August 2010.
