New approaches to treating resistant depression

Cost-effectiveness and threshold analysis of deep brain stimulation vs. treatment-as-usual for treatment-resistant depression

Treatment-resistant depression (TRD) affects approximately 2.8 million people in the U.S. with estimated annual healthcare costs of $43.8 billion. Deep brain stimulation (DBS) is currently an investigational intervention for TRD. We used a decision-analytic model to compare cost-effectiveness of DBS to treatment-as-usual (TAU) for TRD. Because this therapy is not FDA approved or in common use, our goal was to establish an effectiveness threshold that trials would need to demonstrate for this therapy to be cost-effective. Remission and complication rates were determined from review of relevant studies. We used published utility scores to reflect quality of life after treatment. Medicare reimbursement rates and health economics data were used to approximate costs. We performed Monte Carlo (MC) simulations and probabilistic sensitivity analyses to estimate incremental cost-effectiveness ratios (ICER; USD/quality-adjusted life year [QALY]) at a 5-year time horizon. Cost-effectiveness was defined using willingness-to-pay (WTP) thresholds of $100,000/QALY and $50,000/QALY for moderate and definitive cost-effectiveness, respectively. We included 274 patients across 16 studies from 2009-2021 who underwent DBS for TRD and had ≥12 months follow-up in our model inputs. From a healthcare sector perspective, DBS using non-rechargeable devices (DBS-pc) would require 55% and 85% remission, while DBS using rechargeable devices (DBS-rc) would require 11% and 19% remission for moderate and definitive cost-effectiveness, respectively. From a societal perspective, DBS-pc would require 35% and 46% remission, while DBS-rc would require 8% and 10% remission for moderate and definitive cost-effectiveness, respectively. DBS-pc will unlikely be cost-effective at any time horizon without transformative improvements in battery longevity. If remission rates ≥8-19% are achieved, DBS-rc will likely be more cost-effective than TAU for TRD, with further increasing cost-effectiveness beyond 5 years.

Management of lithium intoxication

Lithium is a gold standard maintenance treatment in bipolar affective disorder. It has a narrow therapeutic range, and at higher serum lithium levels there is a risk of adverse effects and toxicity. There are three patterns of lithium intoxication: acute, acute-on-chronic and chronic. We describe risk factors for lithium intoxication, mechanisms of toxicity and clinical symptoms seen in lithium intoxication. We describe both the acute and chronic effects of lithium toxicity. Lithium intoxication may be life-threatening and associated with longer-term sequelae. The management of lithium intoxication involves determining the type of intoxication. We discuss treatment strategies aimed at reducing absorption and increasing elimination of lithium. We discuss clinical indications for extracorporeal methods such as dialysis, which are used to limit the time and degree of exposure of the central nervous system to toxic lithium concentrations. Haemodialysis is the most rapid method of eliminating lithium from the body, but careful monitoring is required. Preventive strategies to mitigate the risk for lithium intoxication are discussed.

Treatment-resistant depression: therapeutic options when first-line treatments fail

The Cochrane review by Davies et al aimed to address the lack of clarity on the risks and benefits of switching and augmentation strategies in the pharmacological treatment of treatment-resistant depression in adults who did not respond (or partially responded) to at least 4 weeks of antidepressant treatment at a recommended dose. This commentary assesses their review and their conclusion that augmenting the current antidepressant with mianserin or with an antipsychotic improves depressive symptoms over the short-term (8 to 12 weeks). Their results need to be treated with caution owing to the small body of evidence and individual comparisons supported by one, two or three studies, the limited evidence on long-term effects and the significant gaps in the literature (e.g. a lack of studies assessing dose increases).

Predicting treatment effects in unipolar depression: A meta-review

There is increasing interest in clinical prediction models in psychiatry, which focus on developing multivariate algorithms to guide personalized diagnostic or management decisions. The main target of these models is the prediction of treatment response to different antidepressant therapies. This is because the ability to predict response based on patients' personal data may allow clinicians to make improved treatment decisions, and to provide more efficacious or more tolerable medications to the right patient. We searched the literature for systematic reviews about treatment prediction in the context of existing treatment modalities for adult unipolar depression, until July 2019. Treatment effect is defined broadly to include efficacy, safety, tolerability and acceptability outcomes. We first focused on the identification of individual predictor variables that might predict treatment response, and second, we considered multivariate clinical prediction models. Our meta-review included a total of 10 systematic reviews; seven (from 2014 to 2018) focusing on individual predictor variables and three focusing on clinical prediction models. These identified a number of sociodemographic, phenomenological, clinical, neuroimaging, remote monitoring, genetic and serum marker variables as possible predictor variables for treatment response, alongside statistical and machine-learning approaches to clinical prediction model development. Effect sizes for individual predictor variables were generally small and clinical prediction models had generally not been validated in external populations. There is a need for rigorous model validation in large external data-sets to prove the clinical utility of models. We also discuss potential future avenues in the field of personalized psychiatry, particularly the combination of multiple sources of data and the emerging field of artificial intelligence and digital mental health to identify new individual predictor variables.

Prescribing for moderate or severe unipolar depression in patients under the long-term care of UK adult mental health services

BACKGROUND

A quality improvement programme addressing prescribing practice for depression was initiated by the Prescribing Observatory for Mental Health.

METHODS

A baseline clinical audit against evidence-based practice standards was conducted in UK adult mental health services.

RESULTS

A total of 55 mental health services submitted data for 2082 patients, under the care of a community psychiatric team (CMHT) for at least a year, with a diagnosis of moderate or severe unipolar depression, 54% of whom had a comorbid psychiatric diagnosis. Selective serotonin reuptake inhibitors were prescribed for 35% of the patients, other newer generation antidepressants for 60%, tricyclic antidepressants for 6% and monoamine oxidase inhibitors for <1%. The most commonly prescribed individual antidepressants were mirtazapine (33%, usually in combination with another antidepressant), venlafaxine (25%) and sertraline (21%). Patients with severe depression were more likely (p < 0.001) to be co-prescribed an antipsychotic medication, lithium, or to have received electroconvulsive therapy. There was a documented clinical review in the last year in 85%, with a symptom rating scale used in 11%. A documented comprehensive treatment history was accessible for 50% of those prescribed antidepressant medication.

CONCLUSION

Patients with moderate or severe depression remaining under the care of a CMHT for longer than a year are clinically complex. The failure to achieve a level of wellness allowing discharge from mental health services may be partly related to the finding that not all patients had the benefit of a systematic approach to clinical assessment and sequential testing of available evidence-based pharmacological interventions.

Backing into the future: pharmacological approaches to the management of resistant depression

Pragmatic studies indicate that a substantial number of depressed patients do not remit with current first-line antidepressant treatments and after two failed treatment steps the chance of remission with subsequent therapies is around 15%. This paper focuses on current evidence for pharmacological treatments in resistant depression as well as possible future developments. For patients who have failed to respond to two antidepressant trials, augmentation with atypical antipsychotic drugs, specifically quetiapine and aripiprazole, has the best evidence for efficacy, though older treatments such as lithium and triiodothyronine still have utility. The striking antidepressant effect of ketamine in resistant depression has stimulated research into glutamatergic compounds; however, capturing the efficacy of ketamine with drugs suitable for continuous use has proved challenging. Growing knowledge of the pathophysiological role of inflammation in depression offers great opportunities for future treatment in terms of repurposing anti-inflammatory agents from general medicine and pre-treatment stratification of those depressed patients in whom such interventions are likely to be beneficial. Finally an older drug, the dopamine receptor agonist pramipexole, if used carefully may well improve the prospects of depressed patients who are refractory to current approaches.