The Impact of (the Concept of) Treatment-Resistant Depression: An Opinion Review.

Treatment-resistant depression refers to major depressive disorder, treatment of the disorder, and failure to obtain an "acceptable" outcome. Regarding the disorder, the heterogeneous concept of major depressive disorder and the multiple definitions of treatment-resistant depression, hesitating between a categorical and a more dimensional approach, as well as the divergence between diagnostic criteria and the items in the assessment scales are a source of confusion. Classifications do not take into account the dramatic influence of patient characteristics strongly impacting outcome, although these can be the cause of so-called pseudo-resistance. Outcome is the result of spontaneous evolution, nonspecific factors (including placebo), and active treatment factors. These should be differentiated to have a reliable estimation of the impact of different treatment modalities before we can asses treatment-resistant depression or before we can ascertain the (non)efficacy of treatments for treatment-resistant depression.The impact and burden of major depressive disorder and treatment-resistant depression are immense and go far beyond their economic cost. It is often forgotten that both are not only associated with increased suicidality but also with nonsuicidal mortality and that both can even result in requests for assisted dying. The caregiver burden and associated stigma are also too often overlooked despite that it has been suggested that they do influence (treatment) outcome.

Mortality in treatment-resistant unipolar depression: A register-based cohort study in Sweden.

BACKGROUND: The impact of treatment resistant depression (TRD) on mortality is not established. METHODS: Using Swedish national registers, 118,774 patients between 18-69 years of age who had been prescribed an antidepressant and been diagnosed with depression in specialized care were identified. Patients with at least two additional treatment trials during the same depressive episode were classified as having TRD. Data on the covariates of sex, age, history of depression, self-harm, substance use disorders, and other psychiatric and somatic comorbidities was also used. Relative risks comparing TRD patients with other depressed patients were calculated as hazard ratios (HR) for all-cause mortality and for external and non-external causes of death, as well as excess mortality rate ratios (EMRR), with 95% confidence intervals (CI). RESULTS: In total 15,013 patients (13%) were classified with TRD. Adjusted HR for all-cause mortality was 1.35 (95% CI 1.21-1.50). Mortality from external causes (including suicides and accidents) was markedly higher in TRD patients than in other depressed patients (HR 1.97; 1.69-2.29), while mortality from non-external causes was similar. The adjusted EMRR was 1.52 (1.31-1.76), highest among patients 18-29 years old (EMRR 2.03; 1.31-1.76) and patients without somatic comorbidity (EMRR 1.99; 1.63-2.43). LIMITATIONS: Severity of depression and adherence to treatment were not available in the data. CONCLUSIONS: Patients with TRD may have an increased all-cause mortality compared to other depressed patients, mainly for external causes of death. The relative mortality is highest among young and physically healthy patients.

Prediction of longer-term outcome of treatment-resistant depression in tertiary care.

BACKGROUND: Systematic studies on the outcome of treatment-resistant depression are scarce. AIMS: To describe the longer-term outcome and predictors of outcome in treatment-resistant depression. METHOD: Out of 150 patients approached, 118 participants with confirmed treatment-resistant depression (unipolar, n = 77; bipolar, n = 27; secondary, n = 14) treated in a specialist in-patient centre were followed-up for between 8 and 84 months (mean = 39, s.d. = 22). RESULTS: The majority of participants attained full remission (60.2%), most of whom (48.3% of total sample) showed sustained recovery (full remission for at least 6 months). A substantial minority had persistent subsyndromal depression (19.5%) or persistent depressive episode (20.3%). Diagnosis of bipolar treatment-resistant depression and poorer social support were associated with early relapse, whereas strong social support, higher educational status and milder level of treatment resistance measured with the Maudsley Staging Method were associated with achieving quicker remission. Exploratory analysis of treatment found positive associations between treatment with a monoamine oxidase inhibitor (MAOI) in unipolar treatment-resistant depression and attaining remission at discharge and at final follow-up, and duloxetine use predicted attainment of remission at final follow-up. CONCLUSIONS: Although many patients with treatment-resistant depression experience persistent symptomatology even after intensive, specialist treatment, most can achieve remission. The choice of treatment and presence of good social support may affect remission rates, whereas those with low social support and a bipolar diathesis should be considered at higher risk of early relapse. We suggest that future work to improve the long-term outcome in this disabling form of depression might focus on social interventions to improve support, and the role of neglected pharmacological interventions such as MAOIs.

Treatment-resistant and insufficiently treated depression and all-cause mortality following myocardial infarction.

BACKGROUND: Depression is a known risk factor for mortality after an acute myocardial infarction. Patients with treatment-responsive depression may have a better prognosis than those with treatment-resistant depression. AIMS: We sought to determine whether mortality following acute myocardial infarction was associated with treatment-resistant depression. METHOD: Follow-up began after myocardial infarction and continued until death or censorship. Depression was counted as present if diagnosed any time during the study period. Treatment for depression was defined as receipt of 12 or more weeks of continuous antidepressant therapy at a therapeutic dose during follow-up. Treatment-resistant depression was defined as use of two or more antidepressants plus augmentation therapy, receipt of electroconvulsive therapy or use of monoamine oxidase inhibitors. Mean duration of follow-up was 39 months. RESULTS: During follow-up of 4037 patients with major depressive disorder who had had a myocardial infarction, 6.9% of those with insufficiently treated depression, 2.4% of those with treated depression and 5.0% of those with treatment-resistant depression died. A multivariable survival model that adjusted for sociodemographics, anxiety disorders, beta-blocker use, mortality risk factors and health service utilisation indicated that compared with treated patients, insufficiently treated patients were 3.04 (95% CI 2.12-4.35) times more likely and patients with treatment-resistant depression were 1.71 (95% CI 1.05-2.79) times more likely to die. CONCLUSIONS: All-cause mortality following an acute myocardial infarction is greatest in patients with depression who are insufficiently treated and is a risk in patients with treatment-resistant depression. However, the risk of mortality associated with treatment-resistant depression is partly explained by comorbid disorders. Further studies are warranted to determine whether changes in depression independently predict all-cause mortality.