Eligible studies had to meet the following criteria: they (a) were published in peer-reviewed journals; (b) contained original and independent data; (c) presented sufficient data to calculate the odds ratio (OR) with confidence interval (CI) and P value; (d) were association studies investigating ADH1B Arg/His and (or) ADH1B Arg/Cys; (e) described or referenced appropriate genotyping methods; (f) investigated alcohol, heroin, cocaine, or methamphetamine dependence (or abuse) diagnosed by valid published criteria (tobacco and cannabis were not included due to lack of sufficient relevant publications). For the studies investigating alcoholic liver disease, cirrhosis, or chronic pancreatitis, the cases were considered as alcoholics with the induced diseases due to alcoholism. The patients with cirrhosis were diagnosed by histological, clinical, radiological, and (or) endoscopic findings; (g) had no description of other major psychiatric disorders for patients in the studies (this information was not available in all the studies); and (h) used unrelated individuals in case-control studies. Authors were contacted in cases where we determined it would be useful to have additional information regarding their studies.
