For secondary analyses we performed several subgroup analyses and meta-regression. For
subgroup analyses trials were stratified based on (1) baseline depression severity (mild,moderate or severe) (2) diagnosis (depression with or without co-morbid medical problems, postpartum depression), (3) whether the omega-3 FA preparation was given as monotherapy for depression or given as an augmentation agent to pharmacological treatment, (4) methodological quality of trials and (5) analysis method (intention-to-treat, modified intention-to-treat or completers). For stratification of trials by baseline depression severity we used traditional cutoffs for the HDRS-17 (mild: 28). Trials that measured depression severity on scales other than the HDRS-17 were converted to this scale based on previously defined algorithms. Overall methodological quality of trials was assessed using the JADAD Scale. Because the subgroup analysis based on study quality was not specified a-priori we defined subgroups based on a median split of trial scores on this scale (JADAD=5 vs. JADAD