Approximately 20% of all patients who experience a major depressive episode develop a chronic course [1
] and approximately 47% of patients who are treated in mental health care facility suffer from some form of chronic depression [2
]. Four subtypes of chronic depression are usually distinguished: (1) dysthymia, (2) chronic major depression, (3) recurrent major depression with incomplete remission between episodes, and (4) double depression [3
]. Dysthymic disorder is defined as a mild condition that is chronic and persistent for at least 2
years. Major depressive episode, chronic type, refers to a more severe condition that meets full criteria for major depression continuously for a minimum of 2
years. Patients who have recovered to the point where they no longer meet full criteria for a major depressive episode but continue to experience significant symptoms for a total duration of illness greater than 2
years are referred to as recurrent major depression with incomplete remission during episodes. The superimposition of a major depressive episode on antecedent dysthymia is referred to as double depression [3
Chronic depression is associated with increased functional impairment [4
], increased health care utilization, and higher rates of hospitalization compared with non-chronic forms of depression [1
An increasing number of studies have assessed the effectiveness of several pharmacological, psychotherapeutic, and combined pharmacological and psychotherapeutic interventions for the treatment of chronic depression in the last several decades. Several meta-analyses have confirmed the effectiveness of pharmacological treatments [6
] and systematic reviews have highlighted the effectiveness of psychotherapy in the treatment of chronically depressed patients [8
Because different effective interventions are available for the treatment of chronic depression, a comparative analysis of the effectiveness of these different interventions is of great clinical interest. Although, both systematic reviews and current treatment guidelines recommend combined psychotherapeutic and pharmacological interventions for the treatment of chronic depression, these recommendations are based on a limited amount of evidence [8
Psychotherapy continues to face numerous barriers, such as limited access in underserved areas and higher short-term costs when delivered by mental health care professionals [12
]. Therefore, the delineation of the conditions under which combined treatment provides significantly greater effectiveness than pure pharmacological intervention is of high relevance. However, whether all patients receive equal benefit from the addition of psychotherapy to a pharmacological intervention is not known. A recent meta-analysis reported that the efficacy of psychotherapeutic interventions increases with the number of sessions and patients who suffer from dysthymia receive less benefit from combined treatment compared to pharmacotherapy alone than patients in other diagnostic subgroups [9
Because new data on the comparative effectiveness of combined interventions versus
pharmacotherapy alone are available from a large randomized controlled trial [13
], we decided to summarize empirical evidence on the effectiveness of combined psychotherapeutic and pharmacological treatments for chronic depression compared to pharmacotherapy alone by means of a systematic review. Our aim was to especially focus on outcomes that are relevant for clinicians who treat patients with chronic depression, such as the response to treatment, remission, quality of life, and acceptance of treatments (dropout), and to further examine whether the addition of psychotherapy to a pharmacological intervention is more effective in certain subgroups of patients (e.g.
according to diagnosis).
The objectives of this systematic review are to examine whether the augmentation of pharmacological treatments with psychotherapy is associated with higher effectiveness compared to pharmacotherapy alone and identify possible treatment effect modifiers, i.e. factors that may influence the size of effects of augmentation of pharmacological treatments with psychotherapy.