Heterogeneity Q tests were also performed for differences in OR between the studies using the World Health Organization s International Statistical Classification ofDiseases and Related Health Problems (ICD)(87), the American Psychiatric Association s Diagnostic and Statistical Manual of Mental Disorders (DSM)(88) system, or other identified criteria and studies with no description of diagnosis criteria; between the English-language publications and Chinese-language publications; and between the studies of China-mainland and Taiwan and those of other countries or regions. The results showed that there was only evidence of marginal heterogeneity regarding diagnosis criteria using the recessive model (P(Q) = 0.04), but no heterogeneity using the allelic analysis and dominant model; and weak heterogeneity regarding publication languages using the allelic analysis (P(Q) = 0.01), but no heterogeneity under the dominant and recessive models. The weak heterogeneity between the languages may be due to the heterogeneity between the Asian studies because all the Chinese-language publications were investigating Chinese populations. The results are shown in Table S3 in Supplement 1.
