Randomised controlled trials (RCTs) and cluster-randomised trials of consultation-liaison interventions for adult primary care patients with a diagnosis or symptoms of depression were eligible for inclusion. Consultation-liaison was defined as an intervention where patients were seen once or twice by a mental health professional for assessment (consultation), and with advice to the primary care professional about management (liaison), where no treatment was provided by the mental health professional.
The main outcomes were measures of process of care (likelihood of prescription of an antidepressant) and depression outcomes.
In most of the included trials, patients were recruited by screening for signs/symptoms of depression. Included patients had depressive disorders (one trial), high levels of depressive symptoms (three trials) and were distressed high utilisers (one trial).
The content and process of the consultation-liaison interventions varied between the included trials. The level of interaction between the primary health care professionals and specialist for each patient varied from a single written note report, to joint meetings and a series of up to three discussions. In over half of the included trials, psychiatrists provided the initial assessment of patients; in one trial each a mental health professional and a depression care manager were used for the initial assessment. Comparator treatments included usual care, problem-solving therapy, and specialist involvement without treatment recommendations.
The authors did not state how many reviewers selected the studies.