Definition and impact of treatment-resistant/refractory depression [Definición e impacto de las depresiones resistentes/refractarias al tratamiento]

Major depressive disorder (MDD) is characterized by high rates ofmedical morbidity, low productivity, low life expectancy, and high rates of suicide. Therefore, the treatment of depressed patients involves, among others, an early diagnosis and treatment of the disease. Although an increasing number of antidepressants to treat MDD are available, approximately half of the patients do not respond, and near of two-thirds do not achieve remission after a first treatment attempt. For this project, it was conducted a detailed review using several databases such as MEDLINE, PsycINFO, EMBASE, the Cochrane Library, and LILACS from 1949 to March 2011 crossing terms related to the diagnosis and impact of the DRT. Unfortunately, original publications on DRT in Latin America are scarce and the findings and conclusions of this review have been based almost entirely on Anglo-Saxon scientific evidence. In a similar manner as described by medical microbiology, a major depressive episode (MDE) can be considered refractory when it has not responded to an adequate treatment with an established therapy. What constitutes an inadequate treatment has been the subject of considerable debate, but most experts would probably say it is the failure to achieve remission. The rationale for this approach is that not achieving remission often results in changes in work performance, increased risk of recurrences, chronicity, suicide, and impaired social functioning. Before considering a patient as TRD, is necessary to confirm the diagnosis of unipolar MDD ruling out other psychiatric disorders such as bipolar disorder, or other non-psychiatric medical diseases. After clarifying the diagnosis, and in the absence of remission, the physician is confronted with a great diversity of definitions and clinical criteria suggested for DRT. This variety of diagnostic alternatives, rather than enrich the portfolio of treatment options for DRT, often leads to serious discrepancies that hinder the effective management of the DRT. Unfortunately, more than 50 years after the discovery of the first antidepressants and increased knowledge about the neurobiological mechanisms of MDD and their interactions with the environment, for now there are no uniform guidelines on the definition and treatment of patients with DRT. Perhaps, the most accepted definition of DRT in the literature is that in which an inadequate response after one or two courses of antidepressant treatment with dose optimization, appropriate time of administration (usually between 8 and 12 weeks) and high level of adherence and compliance can be assured. Among the models proposed for the diagnosis of the DRT, Thase and Rush developed a frequently used tool, although with a predictive value, regarding the outcome of treatment, not systematically evaluated. It is based on five steps or levels that arbitrarily assume that the lack of remission after one single trial with an appropriate treatment is just enough to make a diagnosis of DRT. In addition, certain interventions such as tricyclic antidepressants or monoamine oxidase inhibitors are considered superior to first-line strategies available today. This review also defines the differential diagnosis of DRT such as pseudo-resistance, chronic depression, bipolar depression and tachyphylaxis, and describes the costs and consequences of DRT with an inadequate intervention