Long-term efficacy of psychotherapy in major depression: protocol of a
 network meta-analysis

Background: Depression is currently considered the epidemic of the century. In recent decades, research has established that psychotherapy is globally effective for the treatment of depression; however, it remains open which psychotherapeutic treatment is most effective and, particularly, if its efficacy is maintained over the long term. Given the difficulty in performing randomized and controlled clinical trials (RCTs) that simultaneously compare several psychotherapeutic models, meta-analyses aim to provide answers by synthesizing the evidence generated through direct comparisons of treatments.Goals: This protocol describes the meta-analysis study we will perform in order to assess the efficacy and acceptability of long-term results of psychotherapy (i.e., 18-month follow-up or higher) in the treatment of major depression in adults.Methods: Through the use of a recent methodological approach - the network meta-analysis - we will integrate the direct and indirect analysis of evidence from randomized and controlled clinical trials in this domain. We will systematically search seven databases for RCTs of psychotherapy, published since 1994, with evaluation of the efficacy in terms of long-term results for the treatment of depression. All studies with adult participants (18 to 65 years of age) diagnosed with major depression (according to DSM-IV, IV-TR, V or ICD-9, 10) will be eligible and all studies that compare psychotherapy (individual and face-to-face treatment) with a control condition (waiting-list, placebo) will be considered. Data extraction, quality assessment and risk of bias will be carried out independently by three researchers. The primary outcome measure will be the long-term efficacy of treatments (follow-ups of 18 months or above) measured by changes in the overall clinical response and symptoms of depression since post-treatment and follow-ups. The secondary measure will be the acceptability of treatment as measured by the proportion of participants who drop out of follow-up or start another treatment (not psychotherapy). A direct comparison (pairwise meta-analysis) of all studies comparing different psychotherapies will be performed. We will compare relative efficacy and acceptability by indirect comparison, through a bayesian network meta-analysis of random effects to compare different psychological interventions. Further analyses will be conducted if inconsistency and heterogeneity values are found. Discussion: The purpose of this review is to systematize and integrate evidence of long-term maintenance of the results of different psychotherapeutic treatments for major depression, administered individually and face-to-face in RCTs. For this reason, multiple direct and indirect comparisons of treatments (bayesian network) will be made, and the interrelationships between treatments will be estimated in terms of long-term efficacy and acceptability. Even though our scope will be focused on RCTs, we hope that the results obtained can contribute to summarize the present evidence available in terms of long-term results of psychotherapy (i.e., its effectiveness), optimizing the planning of future studies, providing public health guidelines and more informed clinical decisions on the treatment of depression.