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Introduction
Depression is one of the most common chronic illnesses and debilitating mental disorders in the USA. Major depressive disorder has a lifetime prevalence of 17% and a 1-year prevalence of 10%. The annual incidence of major depressive disorder is 3%, and rates of recurrence of this condition are high. 1 2 Depression is a leading cause of significant disability, negatively impacts the quality of life and increases the risk of suicide. 3 4 The costs and healthcare utilisation of depression are staggering, with an annual overall economic burden estimated to have exceeded 80 billion dollars in the USA in 2000. 5 6
Multiple antidepressants are available, with selective serotonin reuptake inhibitors being the most widely used. However, there is increasing concern that the efficacy of antidepressants has been overestimated in clinical trials due to unblinding of drug treatments by adverse events. 7 Reports of industry bias also fuel debate and concern among patients and healthcare providers about the benefit and harms of antidepressants. 8 A meta-analysis has suggested that in mild or moderate depression, improvement with antidepressants may be minimal or non-existent. 9 Another meta-analysis suggested that the relationship between initial severity and antidepressant efficacy is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication. 10
Concerns about antidepressants' efficacy and tolerability in patients with major depressive disorder have led to investigating newer agents with alternative mechanism of action, such as agents that enhance neuroplasticity and neurogenesis. 11 These concerns have also led to increased interest in non-pharmacological treatments for depression.
Several non-pharmacological treatments for depression exist, such as cognitive behavioural therapy, naturopathic interventions, psychotherapy and exercise-based interventions. Studies suggest that these interventions may have a beneficial effect on relapse rates following treatment, 12 which is critical considering the relapsing nature of depression.
The goal of this study is to summarise the best available evidence about the comparative effectiveness of the various non-pharmacological interventions available for the treatment of depression. We aim to appraise the evidence to facilitate shared decision-making and produce an evidence map that highlights knowledge gaps in the field and aid in developing future research agenda.
Methods
Study design
Owing to the large number of interventions and the availability of published...