Assessing cost-effectiveness of drug interventions for schizophrenia

Identifying the serious clinical outcomes of adverse reactions to drugs by a multi-task deep learning framework

Adverse Drug Reactions (ADRs) have a direct impact on human health. As continuous pharmacovigilance and drug monitoring prove to be costly and time-consuming, computational methods have emerged as promising alternatives. However, most existing computational methods primarily focus on predicting whether or not the drug is associated with an adverse reaction and do not consider the core issue of drug benefit-risk assessment-whether the treatment outcome is serious when adverse drug reactions occur. To this end, we categorize serious clinical outcomes caused by adverse reactions to drugs into seven distinct classes and present a deep learning framework, so-called GCAP, for predicting the seriousness of clinical outcomes of adverse reactions to drugs. GCAP has two tasks: one is to predict whether adverse reactions to drugs cause serious clinical outcomes, and the other is to infer the corresponding classes of serious clinical outcomes. Experimental results demonstrate that our method is a powerful and robust framework with high extendibility. GCAP can serve as a useful tool to successfully address the challenge of predicting the seriousness of clinical outcomes stemming from adverse reactions to drugs.

Cost-utility analysis of rTMS as add-on therapy to standard care for the treatment of hallucinations in schizophrenia

Background

This research evaluates the cost-effectiveness of repetitive transcranial magnetic stimulation (rTMS) as add-on therapy to standard care for adults with schizophrenia from an Australian health system perspective.

Methods

A Markov model estimated costs in 2021 Australian dollars and Disability-Adjusted Life-Years (DALYs) averted with rTMS added to standard care compared to standard care alone over 12-months for adults aged 25–65 years with hallucinations in schizophrenia refractory to other therapies. rTMS effect size was sourced from a meta-analysis and converted to a relative risk using the Cochrane conversion method. Probabilistic sensitivity analysis evaluated uncertainty in effect size and disability weights. One-way sensitivity analyses varied rTMS session cost and effectiveness, time horizon and inpatient costs.

Results

The base-case average incremental cost-effectiveness ratio (ICER) was $87,310/DALY averted (95% UI: $10,157–$97,877). Reducing rTMS session cost to $100 lowered the ICER to $9,127/DALY (95% UI: Dominant–$50,699). A 4-year time horizon resulted in rTMS being less costly and more effective (Dominant) than standard care. Decreasing the 3-month probability of relapse with rTMS to 4.6% resulted in a 71% probability of rTMS being cost-effective.

Conclusions

Using a threshold of $50,000/ DALY averted, rTMS as add-on therapy to standard care for the treatment of refractory hallucinations in schizophrenia would not be considered a cost-effective treatment option compared to standard care alone. However, given the refractory nature of this condition and the relatively small size of this population, it may be reasonable for decision-makers to adopt a higher ICER threshold.

Systematic review of the methods of health economic models assessing antipsychotic medication for schizophrenia

BACKGROUND

Numerous economic models have assessed the cost-effectiveness of antipsychotic medications in schizophrenia. It is important to understand what key impacts of antipsychotic medications were considered in the existing models and limitations of existing models in order to inform the development of future models.

OBJECTIVES

This systematic review aims to identify which clinical benefits, clinical harms, costs and cost savings of antipsychotic medication have been considered by existing models, to assess quality of existing models and to suggest good practice recommendations for future economic models of antipsychotic medications.

METHODS

An electronic search was performed on multiple databases (MEDLINE, EMBASE, PsycInfo, Cochrane database of systematic reviews, The NHS Economic Evaluation Database and Health Technology Assessment database) to identify economic models of schizophrenia published between 2005-2020. Two independent reviewers selected studies for inclusion. Study quality was assessed using the National Institute for Health and Care Excellence (NICE) checklist and the Cooper hierarchy. Key impacts of antipsychotic medications considered by exiting models were descriptively summarised.

RESULTS

Sixty models were included. Existing models varied greatly in key impacts of antipsychotic medication included in the model, especially in clinical outcomes used for assessing reduction in psychotic symptoms and types of adverse events considered in the model. Quality of existing models was generally low due to failure to capture the health and cost impact of adverse events of antipsychotic medications and input data not obtained from best available source. Good practices for modelling antipsychotic medications are suggested.

DISCUSSIONS

This review highlights inconsistency in key impacts considered by different models, and limitations of the existing models. Recommendations on future research are provided.

A Systematic Review of Economic Models Across the Entire Schizophrenia Pathway

BACKGROUND

Schizophrenia is associated with a high economic burden. Economic models can help to inform resource allocation decisions to maximise benefits to patients.

OBJECTIVES

This systematic review aims to assess the availability, quality and consistency of conclusions of health economic models evaluating the cost effectiveness of interventions for schizophrenia.

METHODS

An electronic search was performed on multiple databases (MEDLINE, EMBASE, PsycINFO, Cochrane database of systematic reviews, NHS Economic Evaluation Database and Health Technology Assessment database) to identify economic models of interventions for schizophrenia published between 2005 and 2020. Two independent reviewers selected studies for inclusion. Study quality was assessed using the National Institute for Health and Care Excellence (NICE) checklist and the Cooper hierarchy. Model characteristics and conclusions were descriptively summarised.

RESULTS

Seventy-three models met inclusion criteria. Seventy-eight percent of existing models assessed antipsychotics; however, due to inconsistent conclusions reported by different studies, no antipsychotic can be considered clearly cost effective compared with the others. A very limited number of models suggest that the following non-pharmacological interventions might be cost effective: psychosocial interventions, stratified tests, employment intervention and intensive intervention to improve liaison between primary and secondary care. The quality of included models is generally low due to use of a short time horizon, omission of adverse events of interventions, poor data quality and potential conflicts of interest.

CONCLUSIONS

This review highlights a lack of models for non-pharmacological interventions, and limitations of the existing models, including low quality and inconsistency in conclusions. Recommendations on future modelling approaches for schizophrenia are provided.

Systematic review of pharmacoeconomic models for schizophrenia

Background: Economic models are broadly used in the economic evaluation of antipsychotics in schizophrenia. Our objective was to summarize the structure of these models. Methods: Model-based economic evaluations of antipsychotics in schizophrenia were identified through Medline and Embase. General information was extracted including analysis type, model type, perspective, population, comparator, outcome, and timeframe. Model-specific structures for decision tree (DT), cohort- and patient-level Markov model (CLMM, PLMM), and discrete-event simulation (DES) models were extracted. Results: A screen of 1870 records identified 79 studies. These were mostly cost-utility analyses (n = 48) with CLMM (n = 32) or DT models (n = 29). They mostly applied payer perspective (n = 68), focused on general schizophrenia for relapse prevention (n = 73), compared pharmacotherapies as first-line (n = 71), and evaluated incremental cost per quality-adjusted life year (QALY) gained (n = 40) with a 1-year (n = 32) or 5-year (n = 26) projection. DT models progressed with the branching points of response, relapse, discontinuation, and adherence. CLMM models transitioned between disease states, whereas PLMM models transitioned between adverse event states with/without disease state. DES models moved forward with times to remission, relapse, psychiatrist visit, and death. Conclusions: A pattern of pharmacoeconomic models for schizophrenia was identified. More subtle structures and patient-level models are suggested for a future modelling exercise.

A systematic review of health economic models and utility estimation methods in schizophrenia

INTRODUCTION

There is a growing need for economic evaluations describing the disease course, as well as the costs and clinical outcomes related to the treatment of schizophrenia.

AREAS COVERED

A systematic review on studies describing health economic models in schizophrenia and a targeted literature review on utility mapping algorithms in schizophrenia were carried out. Models found in the review were collated and assessed in detail according to their type and various other attributes. Fifty-nine studies were included in the review. Modeling techniques varied from simple decision trees to complex simulation models. The models used various clinical endpoints as value drivers, 47% of the models used quality-adjusted life years, and eight percent used disability-adjusted life years to measure benefits, while others applied various clinical outcomes. Most models considered patients switching between therapies, and therapeutic adherence, compliance or persistence. The targeted literature review identified four main approaches to map PANSS scores to utility values.

EXPERT COMMENTARY

Health economic models developed for schizophrenia showed great variability, with simulation models becoming more frequently used in the last decade. Using PANSS scores as the basis of utility estimations is justifiable.

Biomarkers of treatment outcome in schizophrenia: Defining a benchmark for clinical significance

Emerging data from on imaging and genetic studies have generated interest in "clinically significant" biomarkers to predict response and prognosis. What constitutes "clinical significance" and how a biomarker would reach that threshold are unclear. To develop a benchmark we reviewed different approaches for defining "clinical significance" applied in schizophrenia research and identified that an improvement of 15 points on the PANSS Total is considered meaningful in clinical settings. Using this benchmark and we simulated thousands of schizophrenia trials, using characteristics derived from the NEWMEDS database with over 8000 patients with schizophrenia, to the kind of imaging, genetic, and other biomarkers that could attain clinical significance. We plotted the interaction between frequency-of-occurrence, the effect size of biomarkers and their relationship to the clinical significance threshold. Results show that categorical biomarkers are likely to attain clinical significance when they occur in 20-50% of the clinical population, and can predict at least a 8-10 point PANSS scale difference. Genetic markers are likely to have clinical significance when they occur in 20-50% of the population and can predict 7-9 points on the PANSS scale. A marker with a lower frequency or lesser effect size would find it hard to meet clinical significance thresholds for schizophrenia. The assumptions and limitations of this approach are discussed. Compared with standards in the rest of medicine, biomarkers that can attain this benchmark will be cost-effective and are likely to be adopted by clinical systems.

Can authorities appreciably enhance the prescribing of oral generic risperidone to conserve resources? Findings from across Europe and their implications

BACKGROUND

Generic atypical antipsychotic drugs offer health authorities opportunities for considerable savings. However, schizophrenia and bipolar disorders are complex diseases that require tailored treatments. Consequently, generally there have been limited demand-side measures by health authorities to encourage the preferential prescribing of generics. This is unlike the situation with hypertension, hypercholaesterolaemia or acid-related stomach disorders.The objectives of this study were to compare the effect of the limited demand-side measures in Western European countries and regions on the subsequent prescribing of risperidone following generics; to utilise the findings to provide future guidance to health authorities; and where possible, to investigate the utilisation of generic versus originator risperidone and the prices for generic risperidone.

METHODS

Principally, this was a segmented regression analysis of retrospective time-series data of the effect of the various initiatives in Belgium, Ireland, Scotland and Sweden following the introduction of generic risperidone. The study included patients prescribed at least one atypical antipsychotic drug up to 20 months before and up to 20 months after generic risperidone. In addition, retrospective observational studies were carried out in Austria and Spain (Catalonia) from 2005 to 2011 as well as one English primary care organisation (Bury Primary Care Trust (PCT)).

RESULTS

There was a consistent steady reduction in risperidone as a percentage of total selected atypical antipsychotic utilisation following generics. A similar pattern was seen in Austria and Spain, with stable utilisation in one English PCT. However, there was considerable variation in the utilisation of generic risperidone, ranging from 98% of total risperidone in Scotland to only 14% in Ireland. Similarly, the price of generic risperidone varied considerably. In Scotland, generic risperidone was only 16% of pre-patent loss prices versus 72% in Ireland.

CONCLUSION

Consistent findings of no increased prescribing of risperidone post generics with limited specific demand-side measures suggests no 'spillover' effect from one class to another encouraging the preferential prescribing of generic atypical antipsychotic drugs. This is exacerbated by the complexity of the disease area and differences in the side-effects between treatments. There appeared to be no clinical issues with generic risperidone, and prices inversely reflected measures to enhance their utilisation.

Generic atypical antipsychotic drugs in Belgium: their influence and implications

Introduction: Generic atypical antipsychotic drugs should be a focus of attention given their expenditure. However, there is a recognized need to tailor treatments. There were no specific measures in Belgium to enhance the prescribing of oral risperidone following generics in January 2008. Prescribing restrictions have remained for long-acting risperidone injections throughout. Objective: Assess changes in risperidone utilization before and after oral generics were reimbursed, as well as the utilization and expenditure of the various risperidone preparations. Method: Principally a retrospective observational study and interrupted time series design. Results: As expected, no increased utilization of oral risperidone after generics. Both originator and generic oral risperidone prescribed, with the originator reducing its price. Generic risperidone was 59% below prepatent loss prices by September 2012. Conclusion: Authorities cannot rely on a ‘spill over’ of learning from other disease areas to affect changes in physician prescribing habits. Specific measures are needed to encourage generic risperidone where appropriate. However, their influence will be limited by the complexity of the disease area.

Are specific initiatives required to enhance prescribing of generic atypical antipsychotics in Scotland?: International implications

BACKGROUND

National and regional authorities in Scotland have introduced multiple measures to appreciably enhance prescribing efficiency for the proton pump inhibitors (PPIs), statins and renin-angiotensin inhibitor drugs. Generic oral risperidone recently became available in Scotland; however, schizophrenia is a complex disease with advice from respected authorities suggesting that treatment should be individualised.

AIMS

To assess (i) changes in atypical antipsychotic drug (AAP) utilisation and expenditure following the availability of oral generic risperidone in Scotland; (ii) to determine (a) current INN prescribing rates for risperidone following generic availability and (b) decrease in expenditure/DDD for generic risperidone; (iii) to suggest additional measures that could possibly be introduced in Scotland to further enhance prescribing of generic AAPs; and (iv) to provide guidance to NHS Scotland as well as other European authorities on the implications.

METHODS

Retrospective observational study and an interrupted time series design.

RESULTS

No appreciable change in the utilisation patterns of risperidone pre- and postgeneric availability. Appreciable INN prescribing averaged 93-98% of total oral risperidone. Generic risperidone was 84% below prepatent loss prices by study end, reducing annual expenditure for oral risperidone in 2010 by GB£3.19mn compared with prepatent loss situation. However, overall expenditure on AAPs increased by 42% from 2005 to 2010.

DISCUSSION

As expected, there was no change in utilisation patterns for risperidone, although potential to influence prescribing patterns. Continued high INN prescribing suggests no problems with generic risperidone in practice. Costs will start to decrease as more AAPs lose their patents (olanzapine and quetiapine). There is the possibility to accelerate this reduction through educational activities.

CONCLUSION

There is potential to realise some savings with generic AAPs. However, this is limited by the complexity of the disease area. Any measures introduced must aim at increasing the prescribing of generic AAPs first line in suitable patients.

Influence of patient co-payments on atypical antipsychotic choice in Poland: implications once generic atypicals are available

INTRODUCTION

Despite recent concerns over the effectiveness and safety of atypical antipsychotics compared with first-generation antipsychotics, prescribing of atypical antipsychotics continues to increase. The use of generic atypical antipsychotics is one way to address cost concerns, especially if there are no major differences in outcomes between generic and originator formulations. Market forces do appear to help lower prices if patients have to cover any difference between higher priced generics and originators and the current reference-priced products themselves, which they try to avoid, and if companies strive to gain market share. However, this approach may compromise individualizing atypical choice if reference classes consist of several atypicals between which there are significant co-payment differences.

OBJECTIVES

First, to assess whether differences in patient co-payment levels between the various atypical antipsychotic formulations alter the atypical formulation prescribed and/or dispensed in practice in Poland. Second, to assess whether market forces in Poland help drive down generic prices in reality as successive generics are launched. Third, to assess the impact of the reduction in reference prices on the overall expenditure on atypicals by the National Health Fund in Poland.

METHODS

Prescription and reimbursed expenditure data for olanzapine and risperidone were provided by the National Health Fund from 2002 to 2006, although no individual patient data were available. Reimbursement limits for the various presentations of olanzapine and risperidone were based on regulations from the Ministry of Health.

RESULTS

Analysis of the data showed that the level of patient co-payment appeared to impact on the atypical antipsychotic dispensed, with utilization of olanzapine growing once its co-payment was reduced when generic olanzapine became available. The reverse was seen with risperidone, with only limited growth in utilization when co-payment levels increased.Market forces resulted in a 40% reduction in the reimbursed reference price (based on the defined daily dose) of olanzapine and a 77% reduction for risperidone from 2002 to July 2008. These price reductions helped moderate the growth in atypical expenditure in Poland despite appreciably increased utilization, especially for olanzapine. Continued moderation (or even a reduction) in the growth of expenditure on atypicals is envisaged, despite increasing utilization, as more generic formulations are launched, with further reductions in the reference price for both olanzapine and risperidone.

CONCLUSIONS

Market forces appear to drive down the prices of generics and originators as more atypical formulations are launched. However, alternative approaches may be needed if significant co-payment differences compromise individualized care.

Schizophrenia in Thailand: prevalence and burden of disease

Background

A previous estimate of the burden of schizophrenia in Thailand relied on epidemiological estimates from elsewhere. The aim of this study is to estimate the prevalence and disease burden of schizophrenia in Thailand using local data sources that recently have become available.

Methods

The prevalence of schizophrenia was estimated from a community mental health survey supplemented by a count of hospital admissions. Using data from recent meta-analyses of the risk of mortality and remission, we derived incidence and average duration using DisMod software. We used treated disability weights based on patient and clinician ratings from our own local survey of patients in contact with mental health services and applied methods from Australian Burden of Disease and cost-effectiveness studies. We applied untreated disability weights from the Global Burden of Disease (GBD) study. Uncertainty analysis was conducted using Monte Carlo simulation.

Results

The prevalence of schizophrenia at ages 15-59 in the Thai population was 8.8 per 1,000 (95% CI: 7.2, 10.6) with a male-to-female ratio of 1.1-to-1. The disability weights from local data were somewhat lower than the GBD weights. The disease burden in disability-adjusted life years was similar in men (70,000; 95% CI: 64,000, 77, 000) and women (75,000; 95% CI: 69,000, 83,000). The impact of using the lower Thai disability weights on the DALY estimates was small in comparison to the uncertainty in prevalence.

Conclusions

Prevalence of schizophrenia was more critical to an accurate estimate of burden of disease in Thailand than variations in disability weights.

The Queensland Mental Health Clinical Collaborative and the management of schizophrenia

OBJECTIVE

This paper describes the development of a collaborative group of mental health clinicians who have come together to improve practice in adult acute mental health settings for the inpatient management of schizophrenia.

METHOD

Sixteen acute adult mental health inpatient services across Queensland worked together to develop clinical indicators related to the inpatient treatment of schizophrenia. Data collection was conducted by using information available on existing databases and through statewide chart audits using scannable form technology. Through a secure intranet site, and statewide forums, clinicians were able to access information on clinical indicators enabling them to compare their site data to peer and state data.

RESULTS

Available data from 15 of the 16 sites provided information on clinical indicators including average length of stay, 28-day readmission rates, antipsychotic prescribing, medication dose and the use of multiple antipsychotic medications at discharge.

CONCLUSIONS

The formation of the Mental Health Clinical Collaborative has brought together clinicians across the State to develop clinical indicators and openly discuss ideas to inform and improve clinical practice. This process has been effective in improving the quality of routinely collected information across the State and in engaging clinicians in using health information to drive clinical practice.

Outcomes for schizophrenia patients with clozapine treatment: how good does it get?

The objective of this study was to describe the extent/change (2000-2004) of clozapine prescribing in schizophrenia in New Zealand and examine the outcomes associated with increasing treatment duration, and vs. those who discontinue clozapine. Consecutive chart reviews were conducted for adult outpatients in Auckland/Northland regions (T1 = 31 March 2000, T2 = 31 October 2001, T3 = 31 March 2003, T4 = 31 October 2004). Data collected included: patient characteristics, social/functional indicators, diagnosis, duration of illness, psychiatric admissions and treatment information (psychotropic medication, dose, route of administration). Between 2000 and 2004, clozapine for schizophrenia increased from 21.0% to 32.8%. Of those prescribed clozapine at T1, 86.1% were engaged with community services at T4 and 93.2% still prescribed clozapine. Continuing clozapine treatment (vs. other treatment) led to a trend to higher rates of regular occupational activity (37% vs. 14.3%) and lower rates of compulsory treatment (25.1% vs. 46.4%) and significantly lower hospitalisation rates (mean = 0.6 vs. mean = 3.1). For those prescribed clozapine at T4, increasing treatment duration (< or = 10 months, 2-3 years, >3 years) led to a trend to higher rates of living independently (18% vs. 29.2% vs. 34%) and regular occupational activity (26.2% vs. 32.6% vs. 37.5%), and significantly reduced compulsory treatment (44.3% vs. 36.9% vs. 28.6%) and hospitalisation rates in the previous 18 months (1.5 vs. 0.5 vs. 0.2). Clozapine use increased significantly over 4.5 years to expected rates of treatment-resistant schizophrenia. Low clozapine discontinuation rates were found and continuing treatment was associated with real-world improvements in functional and clinical outcomes. These findings support the recommendation of prolonged clozapine trials to improve cost-effectiveness in the most seriously unwell schizophrenia patients.

Cost-effectiveness of a post-splenectomy registry for prevention of sepsis in the asplenic

BACKGROUND

Overwhelming, sometimes fatal infections represent a lifelong risk after surgical removal of the spleen, or in patients who develop hyposplenism as a consequence of illnesses. This risk may be reduced by all or a combination of vaccination, antibiotic prophylaxis and education. We aimed to determine if a registry approach to delivering these interventions would be cost effective using our own experience and published data.

METHOD

The decision model compared a cohort of 1,000 people covered by a registry to a cohort of 1,000 people with no registry. The impact of the registry was assessed in terms of achieved rates of vaccination, chemoprophylaxis and education, consequent outcomes of overwhelming post-splenectomy infection (OPSI) and mortality (years of life lived). The cost-effectiveness of the registry compared with no registry was estimated in terms of additional cost per case of OPSI avoided and as additional cost per life year gained.

RESULTS

In the first two years, the additional cost of the registry was dollar 152,611 per case of OPSI avoided or dollar 205,931 per life year gained. After this initial registration period the cost-effectiveness improves over time, such that over the cohort lifetime a post-splenectomy register is associated with an additional cost of dollar 105,159 per case of OPSI avoided or dollar 16,113 per life year gained.

CONCLUSION

A registry-based approach is likely to prove cost effective in terms of mortality and rates of OPSI avoided.

Comparing the Incomparable? A Systematic Review of Competing Techniques for Converting Descriptive Measures of Health Status into QALY-Weights

Background . Algorithms for converting descriptive measures of health status into quality-adjusted life year (QALY)—weights are now widely available, and their application in economic evaluation is increasingly commonplace. The objective of this study is to describe and compare existing conversion algorithms and to highlight issues bearing on the derivation and interpretation of the QALY-weights so obtained. Methods . Systematic review of algorithms for converting descriptive measures of health status into QALY-weights. Results . The review identified a substantial body of literature comprising 46 derivation studies and 16 studies that provided evidence or commentary on the validity of conversion algorithms. Conversion algorithms were derived using 1 of 4 techniques: 1) transfer to utility regression, 2) response mapping, 3) effect size translation, and 4) “revaluing” outcome measures using preference-based scaling techniques. Although these techniques differ in their methodological/theoretical tradition, data requirements, and ease of derivation and application, the available evidence suggests that the sensitivity and validity of derived QALY-weights may be more dependent on the coverage and sensitivity of measures and the disease area/patient group under evaluation than on the technique used in derivation. Conclusions . Despite the recent proliferation of conversion algorithms, a number of questions bearing on the derivation and interpretation of derived QALY-weights remain unresolved. These unresolved issues suggest directions for future research in this area. In the meantime, analysts seeking guidance in selecting derived QALY-weights should consider the validity and feasibility of each conversion algorithm in the disease area and patient group under evaluation rather than restricting their choice to weights from a particular derivation technique.