Classification of Treatments
Because psychological treatments are considered complex interventions,24 grouping them can be performed along several dimensions and remains controversial.25 Our classification system was largely prespecified and followed published models,8 but it needed some modification to account for the clinical heterogeneity in the identified primary studies. We grouped interventions according to the following dimensions: (1) theoretical background—cognitive behavioral therapy (CBT) vs problem-solving therapy vs interpersonal therapy vs psychodynamic therapies vs other interventions; (2) intensity of contact with health care professional—intensively therapist-led (with a minimum of 6 sessions) vs guided self-help (with less than 6 sessions) vs no or minimal contact (with less than 90 minutes of contact) interventions; and (3) face-to-face vs remote contact interventions. Although not all dimensions of this classification system are completely independent, and not all possible combinations present realistic alternatives, we considered it both comprehensive and sufficiently sophisticated to describe reasonably differentiated treatment options that may be present in everyday care and may be relevant to health policy decision making concerning primary care patients with depression.