Study designs of evaluations included in the review
Inclusion criteria for the study design were not explicitly stated.
Specific interventions included in the review
Studies evaluating lithium were eligible. Additional treatments provided to both patients with and without lithium included antidepressants, antipsychotics, anticonvulsants or sedatives. Mean treatment duration was 4.56 years (standard deviation, SD=2.53) in patients receiving lithium and 6.27 years (SD=4.84) in the group without lithium.
Participants included in the review
Studies of patients with recurrent MDD as diagnosed by the International Classification of Diseases (ICD-9), American Psychiatric Association's DSM III/IV criteria, or equivalents were eligible for inclusion.
Outcomes assessed in the review
Studies that provided data on suicidal behaviour were eligible for inclusion. The primary outcomes reported were the rates of suicide or suicide attempts in patients with recurrent MDD.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.