Studies were classified according to inclusion criteria, as “alcoholics with alcoholic liver disease”; “alcoholics with cirrhosis or pancreatitis”; “alcoholics not known to have alcoholic liver disease, cirrhosis, or pancreatitis (or without medical comorbidity specified)”; and “other groups”, e.g., heroin dependence (abuse). A study that contained data from more than one population groups (e.g., Asian and Mexican American) was considered effectively as multiple independent studies. Data from the included studies were summarized by two-by-two tables. From each table a log-odds ratio and its sampling variance were calculated. The Cochran’s χ2-based Q statistic test was performed in order to assess heterogeneity (Zintzaras and Ioannidis 2005) to ensure that each group of studies was suitable for meta-analysis. Where heterogeneity was found, the random effects model, which yields a wider CI, was adopted; otherwise, both the fixed and random effects models were used. Heterogeneity Q tests were also performed for differences in OR between studies using the World Health Organization’s International Statistical Classification of Diseases and Related Health Problems (ICD) (World Health Organization) or the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental
