Study designs of evaluations included in the review
No inclusion criteria were specified with regard to the study design. Only randomised controlled trials (RCTs) were included.
Specific interventions included in the review
Collaborative care interventions for patients with depression in primary care were eligible for inclusion. These were defined as multifaceted organisational interventions such as the introduction of case managers, mechanisms to improve liaison between primary care clinicians and mental health specialists, and systems to manage information on the progress of individual patients. The authors excluded educational and training initiatives and the provision of brief psychological therapy where these were the sole intervention.
The specific interventions in the individual studies were not described, but a table reported intervention content variables of interest for the eight variables included in analysis. Of the 34 studies, primary care physicians received training in 15, case managers had a mental health background in 17, the number of case management sessions was five or more in 21, and case managers had regular or planned supervision in 24. The case management content included medication management in all studies but also included psychological therapy in 13 of the 34 studies. Other variables of interest concerned the study setting and methodology. Most of the studies (27 out of 34) were set in the USA.
Participants included in the review
Participants eligible for inclusion were patients with depressive symptoms, or with a diagnosis of depression, in a primary care setting.
Where the information was reported, the participants in the included studies were adults (26 studies) or elderly people (6 studies) in primary care. A single study was restricted to adult women. The participants had either depressive symptoms (5 studies) or a formal diagnosis of depression (27 studies). In almost half of the studies the participants were starting treatment, generally with a new antidepressant, or were changing treatment (16 studies). In several studies the patients had co-morbidities such as dysthymia (10 studies), diabetes, substance abuse or minor depression (1 study each), or were at high risk of relapse or recurrence (3 studies).
Outcomes assessed in the review
Outcomes eligible for inclusion were changes in measures of antidepressant use and a reduction in depressive symptoms. Where alternative measures of depressive outcomes were reported, priority was given to the primary study outcome and then to observer-rated scales over self-report measures. All studies reported one or both of the outcomes of interest. The analysis was restricted to short-term outcomes (at approximately 6 months follow-up) in order to maximise the data available.
How were decisions on the relevance of primary studies made?
The authors did not state how the studies were selected for the review, or how many reviewers performed the selection.