Two investigators (KK and SS) independently extracted the relevant p value from each study. There were no cases of disagreement between the two investigators. When several p values were provided (due to the use of several depression scales or separate p values for different subsets of samples) we used a weighted mean p value for our analyses. For studies with non-significant results that did not provide exact probabilities, a p value of 1 (no association in either direction) was assumed. When an article reported analyses that matched different groups of our study, we incorporated the mean of the p value of each group into the overall analysis.
