In order to explore the sources of heterogeneity, we performed meta-regression analysis considering mean age, gender (percent of men), adjusted/unadjusted effect estimates, and a high/low risk of bias as covariates (Table 2). Multivariate meta-regression indicates the impact of moderator variables on study effect size. According to the results of meta-regression analysis, none of the covariates had a significant effect on the observed heterogeneity. The effects of covariates in the meta-regression are presented based on a logarithmic scale, so that it is possible to estimate the risk of suicidal ideation, attempted suicide, and completed suicide based on different scenarios of moderator variables.
