Healthcare utilization, costs, and productivity losses in treatment-resistant depression in Finland - a matched cohort study.

BACKGROUND: Due to its relatively high prevalence and recurrent nature, depression causes a major burden on healthcare systems, societies and individuals. Our objective was to investigate healthcare resource utilization and costs associated with treatment-resistant depression (TRD) compared with non-treatment-resistant depression in Finland. METHODS: Of all patients aged 16-65 years and diagnosed with depression in Finland during 2004-2016, persons with TRD (N = 15,405) were identified from nationwide registers and matched 1:1 with comparison persons with depression who initiated antidepressant use but did not have TRD at the time of matching. TRD was defined as initiation of a third treatment trial after having failed two pharmacological treatment trials. Follow-up period covered 5 years after TRD or corresponding matching date (until end of 2018). Health care resource utilization was studied with negative binomial regression and costs of TRD (per patient per year) with generalized estimating equations, by adjusting for baseline costs, comorbidity and baseline severity of depression. RESULTS: Persons with TRD (mean age 38.7, SD 13.1, 60.0% women) had more health care utilization and work disability (sick leaves and disability pensions), adjusted incidence rate ratio for work disability days was 1.72 (95% CI 1.64-1.80). This resulted in 1.9-fold higher total costs for persons with TRD (15,907 versus 8335 EUR), adjusted mean difference 7572 (95% CI 7215-7929) EUR per patient per year, higher productivity losses (due to sick leaves and disability pensions, mean difference 5296, 95% CI 5042-5550), and direct healthcare costs (2003, 95% CI 1853-2151) compared with non-TRD patients. Mean difference was the highest during the first year after TRD (total costs difference 11,760, 95% CI 11,314-12,206) and the difference decreased gradually after that. CONCLUSION: Treatment-resistant depression is associated with about two-fold cost burden compared with non-treatment-resistant depression.

Remission and Treatment Augmentation of Depression in the United States.

Objective: To determine the proportion of adults treated for depression in the US who achieve remission and, among those not achieving remission, the proportion receiving augmentation treatment.Methods: Using data from the US National Health and Nutrition Examination Survey (NHANES) for years 2013-2014, 2015-2016, and 2017-2018, we identified 869 adults who reported using antidepressant medications for depression for at least 3 months. This sample was partitioned into remitted (score < 5) and non-remitted (score ≥ 5) respondents based on 9-item Patient Health Questionnaire (PHQ-9) score-a questionnaire based on the DSM-IV criteria for major depressive disorder. Among the non-remitted group, the proportion receiving antidepressant augmentation with another antidepressant medication of a different class or other medications was also assessed.Results: An estimated 43.5% of adults receiving antidepressant medications for depression were in remission when assessed. Among those not in remission, 28.1% were using augmentation treatment, which in most cases was another antidepressant medication from a different class. As compared to depressed adults without any mental health contact in the past year, those with such contact had significantly higher odds of using augmentation treatment (adjusted odds ratio = 2.72; 95% CI, 1.56-4.76; P = .001).Conclusions: The low percentage of US adults treated with antidepressants for depression that achieves remission represents a missed clinical and public health opportunity to optimize depression treatment. Closer monitoring of symptoms through measurement-based care and setting symptom remission as a goal can help improve outcomes for adults with depression.

Predicting Incident Treatment-Resistant Depression: A Model Designed for Health Systems of Care.

BACKGROUND: Major depressive disorder (MDD) is a prevalent and debilitating condition. While numerous treatment options are available, low treatment response and high remission rates remain common, leading to the concept of treatment-resistant depression (TRD): a classification applied to patients who fail multiple courses of therapy. A patient with TRD can only be identified after repeated, and often prolonged, therapeutic efforts. OBJECTIVE: To use data readily available to integrated delivery networks to identify characteristics predictive of TRD among patients initiating pharmacotherapy for MDD. METHODS: Decision Resources Group Real-World Data, an integrated medical/pharmacy claims and electronic health record dataset, was used to conduct a retrospective, longitudinal cohort study of patients with MDD who initiated antidepressant treatment between July 1, 2014, and December 31, 2015. Individuals were followed for 24 months to determine treatment resistance. Eligible individuals had integrated claims and electronic health record data available, completed at least 1 course of therapy of adequate dose and duration to achieve response, and had 30 months of continuous benefits eligibility (6 months before and 24 months after treatment initiation). Stepwise logistic regression and demographic, health history, health care utilization, medication, provider, and related characteristics were used to predict onset of TRD. RESULTS: 35,246 people met eligibility and 7,098 (20.1%) met TRD criteria after an average of 402 days. Significant predictors of TRD included patient age, diagnosis of insomnia and hypertension, psychiatric office visits, nurse telephonic encounters, anticonvulsant medication use, suicidality, physician specialty associated with index prescription, total prescription drug claims, unique antidepressants attempted, and duration of untreated illness (the lag between diagnosis and index prescription). The final model achieved an area under the curve (AUC) = 0.83. Structured patient-generated health data, specifically, the Patient Health Questionnaire-2 and the Patient Health Questionnaire-9 were only reported for 542 patients (1.5%). CONCLUSIONS: TRD transition occurs after a prolonged treatment period, suggesting clinical inertia. Using data routinely available to integrated delivery networks and accountable care organizations, it is feasible to identify patients likely to qualify as treatment resistant. Monitoring risk factors may allow health systems to identify patients at risk for TRD earlier, potentially improving outcomes. Early identification of this at-risk population can allow for targeted resources for earlier intervention, more aggressive follow-up, and alternative treatment options. Furthermore, this model can be used to estimate future demand for specialized care resources, such as those delivered by mood disorder clinics. DISCLOSURES: This project was sponsored by Janssen Scientific Affairs. Pesa, Chow, and Verbanac are employed by Janssen Scientific Affairs and report stock ownership in Johnson & Johnson. Liberman, Davis, Heverly-Fitt, and Ruetsch are employed by Health Analytics, which received funding from Janssen Scientific Affairs for work on this project. This study was presented as a poster at the U.S. Psych Congress; October 3-6, 2019; San Diego, CA.

The Effectiveness and Value of Esketamine for the Management of Treatment-Resistant Depression.

DISCLOSURES: Funding for this summary was contributed by the Laura and John Arnold Foundation, National Institute for Health Care Management, California Health Care Foundation, Blue Cross Blue Shield of Massachusetts, Harvard Pilgrim Healthcare, and Kaiser Foundation Health Plan to the Institute for Clinical and Economic Review (ICER), an independent organization that evaluates the evidence on the value of health care interventions. ICER's annual policy summit is supported by dues from Aetna, America's Health Insurance Plans, Anthem, AstraZeneca, Allergan, Alnylam, Biogen, Blue Shield of California, Cambia Health Services, CVS Caremark, Editas, Express Scripts, Genentech, GlaxoSmithKline, Harvard Pilgrim Health Care, Health Care Service Corporation, HealthPartners, HealthFirst, Johnson & Johnson (Janssen), Kaiser Permanente, LEO Pharma, Mallinkrodt Pharmaceuticals, Merck, Novartis, National Pharmaceutical Council, Premera, Prime Therapeutics, Regeneron, Sanofi, Spark Therapeutics, and United Healthcare. Agboola, Fazioli, and Pearson are employed by ICER. Touchette reports grants from ICER during the course of this work and personal fees from Monument Analytics, unrelated to this work. Atlas has nothing to disclose.

Dissociating the Clinical Role and Economic Value of Intranasal Esketamine.

DISCLOSURES: No funding supported the writing of this commentary. The author has nothing to disclose.

Staging Treatment Intensity and Defining Resistant Depression: Historical Overview and Future Directions.

OBJECTIVE: To review existing staging models and definitions of treatment-resistant depression (TRD) and offer future directions within the context of up-to-date evidence. DATA SOURCES: A PubMed search was conducted on February 25, 2018, for articles in English on TRD staging or definition using the following keywords: depressive disorder, treatment-resistant OR treatment resistant depression cross-referenced with staging OR degree OR level OR definition. Relevant cross-references from identified articles were also included. STUDY SELECTION: A total of 18 articles were identified that included a proposed TRD staging model, a proposed TRD definition, empirical work to support a model or definition, or any combination thereof. DATA EXTRACTION: Included articles were summarized in chronological order in terms of the date the TRD staging model (and accompanying TRD definition if applicable) was first proposed. Findings from validation studies pertaining to staging or definition were then synthesized. RESULTS: Five staging models were identified. Strengths identified across staging models include rigorous assessment of adequacy of treatment, differentiation of resistance versus symptom return, assignment of equal weights to different pharmacotherapies, and accounting for augmentation. Future considerations should include differential weighting to specific augmentation agents based on available evidence, added weight to electroconvulsive therapy and ketamine treatments, and the addition of evidence-based psychotherapies. Dichotomous versus continuous approaches to TRD diagnosis were considered, with the latter (beginning with 1 failed trial) best explaining available data from large trials. CONCLUSIONS: The most up-to-date evidence in the literature should guide future research in the definition and staging of TRD.

Is clinician impression of depression symptom severity associated with incremental economic burden in privately insured US patients with treatment resistant depression?

BACKGROUND: Among patients with major depressive disorder (MDD), those with treatment-resistant depression (TRD) have a higher economic burden. However, the healthcare resource utilization (HRU) and costs may vary by severity status in TRD patients. This study quantified the incremental economic burden of severity status in TRD patients. METHODS: In a US database of privately insured employees and dependents (07/01/2009-03/31/2015), a claims-based algorithm identified adult TRD patients who were stratified into mild, moderate, and severe cohorts based on the information in the last observed MDD ICD-9-CM code. HRU and costs of moderate and severe cohorts were compared to those of the mild cohort during the 2-year follow-up after the first antidepressant claim. RESULTS: Among 6411 TRD patients, 455 (7.1%) were identified as mild, 2153 (33.6%) as moderate, and 1455 (22.7%) as severe. Moderate and severe patients compared to mild had 45% and 150% more inpatient admissions, 65% and 164% more inpatient days, 18% and 54% more emergency department visits and 8% and 10% more outpatient visits per-patient-per-year (PPPY), respectively (all-cause; all p < 0.05). Mean all-cause direct total healthcare costs were $12,123, $16,885, and $18,911 PPPY in mild, moderate, and severe patients, respectively. The all-cause total healthcare cost differences adjusted for baseline characteristics amounted to $3455 in moderate and $5150 in severe versus mild patients, respectively (PPPY; all p < 0.05). LIMITATIONS: Not all TRD patients had a severity specifier; the severity specifier was not cross-validated against a depression scale. CONCLUSIONS: Increased severity status is associated with incremental economic burden in TRD patients.

The assessment of resistance to antidepressant treatment: Rationale for the Antidepressant Treatment History Form: Short Form (ATHF-SF).

There is considerable diversity in how treatment-resistant depression (TRD) is defined. However, every definition incorporates the concept that patients with TRD have not benefited sufficiently from one or more adequate trials of antidepressant treatment. This review examines the issues fundamental to the systematic evaluation of antidepressant treatment adequacy and resistance. These issues include the domains of interventions deemed effective in treatment of major depressive episodes (e.g., pharmacotherapy, brain stimulation, and psychotherapy), the subgroups of patients for whom distinct adequacy criteria are needed (e.g., bipolar vs. unipolar depression, psychotic vs. nonpsychotic depression), whether trials should be rated dichotomously as adequate or inadequate or on a potency continuum, whether combination and augmentation strategies require specific consideration, and the criteria used to evaluate the adequacy of treatment delivery (e.g., dose, duration), trial adherence, and clinical outcome. This review also presents the Antidepressant Treatment History Form: Short-Form (ATHF-SF), a completely revised version of an earlier instrument, and details how these fundamental issues were addressed in the ATHF-SF.

Current and Emerging Treatments to Address Unmet Needs in MDD.

Most people who experience a depressive episode are greatly impaired by it. No one-size-fits-all therapy is available, and most patients require multiple treatment steps. Check out this CME activity to learn about current and emerging strategies for managing MDD.

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.

Direct and Indirect Cost Burden and Change of Employment Status in Treatment-Resistant Depression: A Matched-Cohort Study Using a US Commercial Claims Database.

BACKGROUND: Treatment-resistant depression (TRD) poses a substantial burden to health care payers including employers, costing an estimated $29 billion-$48 billion yearly in the United States. Furthermore, variation of burden across increasing levels of resistance and the potential impact of TRD on employment status remain largely unexplored. OBJECTIVE: To evaluate health care resource utilization (HRU) and costs, work loss, indirect costs, and employment status change in TRD. METHODS: A claims-based algorithm identified adults with TRD from a US claims database of privately insured employees and dependents (January 2010-March 2015). TRD patients were matched 1:1 on demographics to patients with major depressive disorder (MDD) (non-TRD MDD) and without MDD (non-MDD), who were identified using ICD-9-CM codes. Costs, HRU, and employment status change were compared over 2 years following the first antidepressant (randomly imputed date for non-MDD), adjusting for baseline comorbidity index and costs. RESULTS: TRD patients (N = 6,411) had more HRU than either matched control cohort, translating into higher per patient per year (PPPY) health care costs: $6,709 and $9,917 more than non-TRD MDD and non-MDD patients, respectively (P < .001 for both). TRD patients with work loss data (N = 1,908) had 35.8 work loss days PPPY (1.7 and 6.2 times the work loss rate in non-TRD MDD and non-MDD patients, respectively). Work loss-related costs in TRD patients were $1,811 higher than non-TRD MDD and $3,460 higher than in non-MDD patients (P < .001). TRD patients had 1.3-1.4 times the rate of employment status change versus control cohorts (all P < .05). CONCLUSIONS: TRD, even compared to MDD, poses a significant direct and indirect cost burden to US employers and may be associated with higher rates of employment status change.

Antipsychotic Prescriptions Among Adults With Major Depressive Disorder in Office-Based Outpatient Settings: National Trends From 2006 to 2015.

OBJECTIVE: A recent moderately long-term study found an antipsychotic to be more effective than an antidepressant as the next-step treatment of unresponsive major depressive disorder (MDD). It is thus timely to examine recent trends in the pharmacoepidemiology of antipsychotic treatment of MDD. METHODS: Data from the 2006-2015 National Ambulatory Medical Care Survey, nationally representative samples of office-based outpatient visits in adults with MDD (ICD-9-CM codes 296.20-296.26 and 296.30-296.36) (n = 4,044 unweighted), were used to estimate rates of antipsychotic prescribing over these 10 years. Multivariable logistic regression analysis identified demographic and clinical factors independently associated with antipsychotic use in MDD. RESULTS: Antipsychotic prescribing for MDD increased from 18.5% in 2006-2007 to 24.9% in 2008-2009 and then declined to 18.9% in 2014-2015. Visits with adults 75 years or older showed the greatest decline from 27.0% in 2006-2007 to 10.7% in 2014-2015 (OR for overall trend = 0.73; 95% CI, 0.56-0.95). The most commonly prescribed antipsychotic agents were aripiprazole, olanzapine, quetiapine, and risperidone. Antipsychotic prescription was associated with being black or Hispanic, having Medicare among adults under 65 years or Medicaid as a primary source of payment, and receiving mental health counseling, 3 or more concomitant medications, and diagnosis of cannabis use disorder (P < .01). CONCLUSIONS: Antipsychotics, prescribed for about one-fifth of adults with MDD, increased and then declined from 2006 to 2015, reflecting, first, FDA approval and then concern about adverse effects in the elderly. Future research should track evolving trends following the publication of evidence of greater long-term effectiveness of antipsychotic than antidepressant next-step therapy in adults with MDD.

Study protocol for a randomised pragmatic trial comparing the clinical and cost effectiveness of lithium and quetiapine augmentation in treatment resistant depression (the LQD study).

BACKGROUND: Approximately 30-50% of patients with major depressive disorder can be classed as treatment resistant, widely defined as a failure to respond to two or more adequate trials of antidepressants in the current episode. Treatment resistant depression is associated with a poorer prognosis and higher mortality rates. One treatment option is to augment an existing antidepressant with a second agent. Lithium and the atypical antipsychotic quetiapine are two such add-on therapies and are currently recommended as first line options for treatment resistant depression. However, whilst neither treatment has been established as superior to the other in short-term studies, they have yet to be compared head-to-head in longer term studies, or with a superiority design in this patient group. METHODS: The Lithium versus Quetiapine in Depression (LQD) study is a parallel group, multi-centre, pragmatic, open-label, patient randomised clinical trial designed to address this gap in knowledge. The study will compare the clinical and cost effectiveness of the decision to prescribe lithium or quetiapine add-on therapy to antidepressant medication for patients with treatment resistant depression. Patients will be randomised 1:1 and followed up over 12 months, with the hypothesis being that quetiapine will be superior to lithium. The primary outcomes will be: (1) time to all-cause treatment discontinuation over one year, and (2) self-rated depression symptoms rated weekly for one year via the Quick Inventory of Depressive Symptomatology. Other outcomes will include between group differences in response and remission rates, quality of life, social functioning, cost-effectiveness and the frequency of serious adverse events and side effects. DISCUSSION: The trial aims to help shape the treatment pathway for patients with treatment resistant depression, by determining whether the decision to prescribe quetiapine is superior to lithium. Strengths of the study include its pragmatic superiority design, broad inclusion criteria (external validity) and longer follow up than previous studies. TRIAL REGISTRATION: ISRCTN registry: ISRCTN16387615 , registered 28 February 2016. ClinicalTrials.gov: NCT03004521 , registered 17 November 2016.

Assessing the risk factors for difficult-to-treat depression and treatment-resistant depression.

Depression is the leading cause of disability among people across the globe, according to the World Health Organization. Among those who have been diagnosed, many fail to achieve remission after following recommended antidepressant medication and psychosocial therapies. In particular, difficult-to-treat and treatment-resistant depression may cause severe impairments for patients, including diminished cognitive functioning, increased medical bills, and decreased workplace performance, as well as an increased risk of developing comorbid illnesses. However, many tools are available to clinicians for identifying treatment-resistant depression, including rating scales such as the 9-question Patient Health Questionnaire (PHQ-9) and the Quick Inventory of Depressive Symptomatology (QIDS-SR16), as well as clinical evidence related to risk factors for difficult-to-treat or treatment-resistant depression. Accurately identifying treatment-resistant depression is the first step toward changing treatment regimens to help patients achieve remission.

Cost-Effectiveness of Repetitive Transcranial Magnetic Stimulation versus Antidepressant Therapy for Treatment-Resistant Depression.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) therapy is a clinically safe, noninvasive, nonsystemic treatment for major depressive disorder. OBJECTIVE: We evaluated the cost-effectiveness of rTMS versus pharmacotherapy for the treatment of patients with major depressive disorder who have failed at least two adequate courses of antidepressant medications. METHODS: A 3-year Markov microsimulation model with 2-monthly cycles was used to compare the costs and quality-adjusted life-years (QALYs) of rTMS and a mix of antidepressant medications (including selective serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors, tricyclics, noradrenergic and specific serotonergic antidepressants, and monoamine oxidase inhibitors). The model synthesized data sourced from published literature, national cost reports, and expert opinions. Incremental cost-utility ratios were calculated, and uncertainty of the results was assessed using univariate and multivariate probabilistic sensitivity analyses. RESULTS: Compared with pharmacotherapy, rTMS is a dominant/cost-effective alternative for patients with treatment-resistant depressive disorder. The model predicted that QALYs gained with rTMS were higher than those gained with antidepressant medications (1.25 vs. 1.18 QALYs) while costs were slightly less (AU $31,003 vs. AU $31,190). In the Australian context, at the willingness-to-pay threshold of AU $50,000 per QALY gain, the probability that rTMS was cost-effective was 73%. Sensitivity analyses confirmed the superiority of rTMS in terms of value for money compared with antidepressant medications. CONCLUSIONS: Although both pharmacotherapy and rTMS are clinically effective treatments for major depressive disorder, rTMS is shown to outperform antidepressants in terms of cost-effectiveness for patients who have failed at least two adequate courses of antidepressant medications.

Assessment of the Efficacy and Safety of BMS-820836 in Patients With Treatment-Resistant Major Depression: Results From 2 Randomized, Double-Blind Studies.

Two phase 2B, randomized, double-blind studies assessed the efficacy and safety of fixed or flexible dose of triple monoamine uptake inhibitor BMS-820836 in patients with treatment-resistant depression to demonstrate whether switching to BMS-820836 was superior to the continuation of standard antidepressant treatment. Patients with a history of inadequate response to 1 to 3 adequate trials of antidepressant therapies were prospectively treated with duloxetine 60 mg/d for 8 weeks (CN162-006) or duloxetine 60 mg/d or escitalopram 20 mg/d for 7 weeks (CN162-007). Inadequate responders were randomized to continue their prospective phase treatment or switch to flexible-dose (0.5-2 mg/d; CN162-006) or fixed-dose (0.25, 0.5, 1, or 2 mg/d; CN162-007) BMS-820836 for 6 weeks. The primary end point in both studies was mean change in Montgomery-Åsberg Depression Rating Scale (MADRS) total score from randomization to study end point. BMS-820836 flexible (0.5-2 mg/d) or fixed dose of 1 mg/d or greater showed efficacy similar to the continuation of antidepressant treatment, with no statistically significant or clinically meaningful differences. In the CN162-006 study, the adjusted mean (SE) change in MADRS total score was -8.7 (0.661) and -8.1 (0.656) for BMS-820836 and duloxetine, respectively (P = 0.526). In the CN162-007 study, the adjusted mean (SE) change in MADRS total score was -7.3 (0.830) and -6.6 (0.842) for BMS-820836 of 1 and 2 mg, respectively, and -6.9 (0.602) for the continuation group (P = 0.910). Thus, BMS-820836 was well tolerated, with no evidence of dose-dependent discontinuations due to adverse events, but it failed to demonstrate superiority to the continuation of an existing antidepressant in patients with treatment-resistant depression.

Use of administrative data to identify off-label use of second-generation antipsychotics in a Medicaid population.

OBJECTIVE The use of second-generation antipsychotics for conditions not approved by the U.S. Food and Drug Administration (FDA) is a prevalent phenomenon with important implications. The objective of this study was to determine the accuracy of administrative claims for identifying off-label use of second-generation antipsychotics in a Medicaid population in 2009. METHODS The authors estimated the sensitivity, specificity, positive predictive values (PPV), and negative predictive values of Medicaid claims data for detecting off-label use of second-generation antipsychotics in the electronic health records of 788 patients. Separate estimates were calculated for patients without schizophrenia and bipolar disorder, the two most long-standing FDA indications for use of second-generation antipsychotics, and for a subset of patients using a second-generation antipsychotic with indications for treatment-resistant depression. RESULTS Medicaid claims determined a lack of schizophrenia and bipolar disorder in the medical record with a sensitivity of 72% and a specificity of 85%. The prevalence of identifying neither diagnosis was 83%, which was associated with a predictive ability (PPV) of 96%. Among those using a second-generation antipsychotic with an indication for treatment-resistant depression, the sensitivity, specificity, and PPV of Medicaid claims for identifying off-label use were 41%, 86%, and 87%, respectively. CONCLUSIONS Medicaid claims data had high predictive ability for identifying users of second-generation antipsychotics who did not have documentation of schizophrenia or bipolar disorder in the medical record. The predictive utility of the claims was diminished when the analyses were limited to patients using a second-generation antipsychotic with an indication for treatment-resistant depression.

Cognitive behavioural therapy as an adjunct to pharmacotherapy for primary care based patients with treatment resistant depression: results of the CoBalT randomised controlled trial.

BACKGROUND: Only a third of patients with depression respond fully to antidepressant medication but little evidence exists regarding the best next-step treatment for those whose symptoms are treatment resistant. The CoBalT trial aimed to examine the effectiveness of cognitive behavioural therapy (CBT) as an adjunct to usual care (including pharmacotherapy) for primary care patients with treatment resistant depression compared with usual care alone. METHODS: This two parallel-group multicentre randomised controlled trial recruited 469 patients aged 18-75 years with treatment resistant depression (on antidepressants for ≥6 weeks, Beck depression inventory [BDI] score ≥14 and international classification of diseases [ICD]-10 criteria for depression) from 73 UK general practices. Participants were randomised, with a computer generated code (stratified by centre and minimised according to baseline BDI score, whether the general practice had a counsellor, previous treatment with antidepressants, and duration of present episode of depression) to one of two groups: usual care or CBT in addition to usual care, and were followed up for 12 months. Because of the nature of the intervention it was not possible to mask participants, general practitioners, CBT therapists, or researchers to the treatment allocation. Analyses were by intention to treat. The primary outcome was response, defined as at least 50% reduction in depressive symptoms (BDI score) at 6 months compared with baseline. This trial is registered, ISRCTN38231611. FINDINGS: Between Nov 4, 2008, and Sept 30, 2010, we assigned 235 patients to usual care, and 234 to CBT plus usual care. 422 participants (90%) were followed up at 6 months and 396 (84%) at 12 months, finishing on Oct 31, 2011. 95 participants (46%) in the intervention group met criteria for response at 6 months compared with 46 (22%) in the usual care group (odds ratio 3·26, 95% CI 2·10-5·06, p<0·001). INTERPRETATION: Before this study, no evidence from large-scale randomised controlled trials was available for the effectiveness of augmentation of antidepressant medication with CBT as a next-step for patients whose depression has not responded to pharmacotherapy. Our study has provided robust evidence that CBT as an adjunct to usual care that includes antidepressants is an effective treatment, reducing depressive symptoms in this population. FUNDING: National Institute for Health Research Health Technology Assessment.