A decision model to compare health care costs of olanzapine and risperidone treatment for schizophrenia in Germany

Overview and Use of Tools for Selecting Modelling Techniques in Health Economic Studies

The availability and use of tools to guide the choice of modelling technique are not well understood. Our study aims to review existing tools and explore the use of those tools in health economic models. Two reviews and one case study were conducted. Review 1 aimed to identify tools based on expert opinion and citation searching and explore the value of the tools for health economic models. Review 2, based on citation searching, aimed to describe how those tools have been used in health economic models. Both reviews were conducted using Web of Science and Scopus. Two independent reviewers selected studies for inclusion. A case study, focused on economic evaluations of antipsychotic medication in schizophrenia, was conducted to compare the modelling techniques used by existing models with modelling techniques recommended by identified tools. Seven tools were identified, of which the revised Brennan's toolkit, was assessed to be the most appropriate for health economic models. The seven tools were cited 126 times in publications reporting health economic models. Only 17 of these (13.5%) reported that they used the tool(s) to guide the choice of modelling technique. Application of these tools suggested discrete event simulation is most appropriate for modelling antipsychotic medication in schizophrenia, but discrete event simulation was only used by 17% of existing models. There is considerable inconsistency between the modelling techniques used by existing models and modelling techniques recommended by tools. It is recommended that for future modelling studies the choice of modelling technique should be justified, this can be achieved by the application of model selection tools, such as the revised Brennan's toolkit. Future research is required to explore the barriers to using model selection tools in health economic models and to update existing tools and make them easier to use.

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 utility values used in the pharmacoeconomic evaluations for schizophrenia: implications on cost-effectiveness results

Background and Objectives: Utility elicitation studies for schizophrenia generate different utility values for the same health states. We reviewed utility values used in schizophrenia pharmacoeconomic evaluations and evaluated the impact of their selection on the incremental cost-effectiveness ratio (ICER). Methods: A systematic search was performed in Medline and Embase. Health state definitions, associated utility values, elicitation studies, and value selection processes were extracted. Sets of utility values for all schizophrenia health states were used in a cost-effectiveness model to evaluate the ICER. Results: Thirty-five cost-utility analyses (CUAs) referring to 11 utility elicitation studies were included. The most frequent health states were 'stable' (28 CUAs, 7 utility elicitation studies, 10 values, value range 0.650-0.919), 'relapse requiring hospitalisation' (18, 5, 7, 0.270-0.604), 'relapse not requiring hospitalisation' (18, 5, 10, 0.460-0.762), and 'relapse only' (10, 5, 6, 0.498-0.700). Seventeen sets of utility values were identified with difference in utility values between relapse and stable ranging from -0.358 to -0.050, resulting in ICERs ranging from -56.2% to +222.6% from average. Conclusion: The use of utility values for schizophrenia health states differs among CUAs and impacts on the ICER. More rigorous and transparent use of utility values and sensitivity analysis with different sets of utility values are suggested for future CUAs.

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.

The Cost of Relapse in Schizophrenia

INTRODUCTION

Schizophrenia is a chronic and debilitating mental illness characterised by periods of relapse that require resource intensive management. Quantifying the cost of relapse is central to the evaluation of the cost effectiveness of treating schizophrenia.

OBJECTIVES

We aimed to undertake a comprehensive search of the available literature on the cost of relapse.

METHODS

We performed a search on multiple databases (MEDLINE, Embase, PsycINFO and Health Management Information Consortium) for any study reporting a cost of relapse or data from which such a cost could be calculated. Costs are reported in 2015 international dollars.

RESULTS

We found 16 studies reporting costs associated with relapse over a defined period of time and identified a cost associated with hospitalisation for relapse in 43 studies. Eight clinical decision analyses also provided cost estimates. Studies from the US report excess costs of relapse of $6033-$32,753 (2015 Purchasing Power Parity dollars [PPP$]) over periods of 12-15 months. European studies report excess costs of $8665-$18,676 (2015 PPP$) over periods of 6-12 months. Estimates of the cost of hospitalisation for relapse are more diverse, and associated with marked differences in typical length of stay across jurisdictions.

CONCLUSIONS

Wide ranges in the estimated cost of relapse may reflect differences in sample section and relapse definition as well as practice styles and differences in resource costs. Selection of the most appropriate cost estimate should be guided by the definition of relapse and the analysis setting.

Comparative cost-effectiveness of 11 oral antipsychotics for relapse prevention in schizophrenia within Singapore using effectiveness estimates from a network meta-analysis

This study modelled the cost-effectiveness of 11 oral antipsychotics for relapse prevention among patients with remitted schizophrenia in Singapore. A network meta-analysis determined the relative efficacy and tolerability of 11 oral antipsychotics (amisulpride, aripiprazole, chlorpromazine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone, sulpiride, trifluoperazine and ziprasidone). The clinical estimates were applied in a Markov model to estimate lifetime costs and quality-adjusted life-years gained. Quality-of-life data were obtained from published literature. Resource utilization and cost data were retrieved from local hospital databases. The annual direct cost of healthcare services for a patient experiencing a relapse episode was three-fold that of a patient not in relapse of schizophrenia. The most favourable pharmacological treatment for relapse prevention was olanzapine with an annual probability of relapse of 0.24 (0.13-0.38) with placebo as a reference of 0.75 (0.73-0.78). Olanzapine emerged as the dominant treatment with the highest quality-adjusted life-years gained and lowest lifetime costs. Ziprasidone, aripiprazole and paliperidone incurred higher lifetime costs compared with no treatment. Probability and cost of relapse were key drivers of cost-effectiveness in sensitivity analyses. The data can help prescribers in choosing appropriate treatment and payers in allocating resources for the clinical management of this serious psychiatric disorder.

Validation of an economic model of paliperidone palmitate for chronic schizophrenia

OBJECTIVE

Model validation is important, but seldom applied in chronic schizophrenia. Validation consists of verifying the model itself for face validity (i.e., structure and inputs), cross-validation with other models assessing the same issue, and comparison with real-life outcomes. The primary purpose was to cross-validate a recent pharmacoeconomic model comparing long-acting injectable (LAI) antipsychotics for treating chronic schizophrenia in Sweden. The secondary purpose was to provide external validation.

METHODS

The model of interest was a decision tree analysis with a 1-year time horizon with costs in 2011 Swedish kroner. Drugs analyzed included paliperidone palmitate (PP-LAI), olanzapine pamoate (OLZ-LAI), risperidone (RIS-LAI), haloperidol (HAL-LAI), and oral olanzapine (oral-OLZ). Embase and Medline were searched from 1990-2012 for models examining LAIs. Articles were retrieved, with data extracted for all drugs compared including: expected costs, rates of hospitalization, proportion of time not in relapse, and associated QALYs. Outcomes from the model of interest were compared with those from other articles; costs were projected to 2012 using the consumer price index.

RESULTS

Twenty-six studies were used for validation; 14 of them provided evidence for cross-validation, 13 for external validation, and four for cost. In cross-validation, cost estimates varied -1.8% (range: -12.4-20.1%), hospitalizations 5.2% (-12.1-3.1%), stable disease 2.5% (-5.6-1.5%), QALYs 9.0% (4.3% after removing outliers). All estimates of clinical outcomes were within 15%. In external validation, hospitalization rates varied by 6.3% (-0.7-11.3%). The research was limited by data availability and validity of the original results.

CONCLUSION

Other models validated the outputs of our model very well.

Patterns of relapse and associated cost burden in schizophrenia patients receiving atypical antipsychotics

OBJECTIVE

To identify relapse in schizophrenia and the main cost drivers of relapse using a cost-based algorithm.

METHODS

Multi-state Medicaid data (1997-2010) were used to identify adults with schizophrenia receiving atypical antipsychotics (AP). The first schizophrenia diagnosis following AP initiation was defined as the index date. Relapse episodes were identified based on (1) weeks during the ≥2 years post-index associated with high cost increase from baseline (12 months before the index date) and (2) high absolute weekly cost. A compound score was then calculated based on these two metrics, where the 54% of patients associated with higher cost increase from baseline and higher absolute weekly cost were considered relapsers. Resource use and costs of relapsers during baseline and relapse episodes were compared using incidence rate ratios (IRRs) and bootstrap methods.

RESULTS

In total, 9793 relapsers were identified with a mean of nine relapse episodes per patient. Duration of relapse episodes decreased over time (mean [median]; first episode: 34 [4] weeks; remaining episodes: 8 [1] weeks). Compared with baseline, resource utilization during relapse episodes was significantly greater in pharmacy, outpatient, and institutional visits (hospitalizations, emergency department visits), with IRRs ranging from 1.9-2.4 (all p < 0.0001). Correspondingly, relapse was associated with a mean (95% CI) incremental cost increase of $2459 ($2384-$2539) per week, with institutional visits representing 53% of the increase.

LIMITATIONS

Relapsers and relapse episodes were identified using a cost-based algorithm, as opposed to a more clinical definition of relapse. In addition, their identification was based on the assumption from literature that ~54% of schizophrenia patients will experience at least one relapse episode over a 2-year period.

CONCLUSIONS

Significant cost increases were observed with relapse in schizophrenia, driven mainly by institutional visits.

The cost of relapse in patients with schizophrenia in the European SOHO (Schizophrenia Outpatient Health Outcomes) study

BACKGROUND

Relapse in schizophrenia is one of the greatest burdens of the illness.

AIMS

To estimate the costs associated with relapse in a pan-European naturalistic setting.

METHOD

The SOHO study is a 3-year, prospective, observational study of 10,972 outpatients with schizophrenia across 10 European countries. The cost of resource use (inpatient stay, day care, psychiatrist visits and medication) for those who ever relapsed in three years was compared to those who never relapsed. One-year costs for both groups were also compared for a more stringent comparison. The analyses were adjusted for patient characteristics and took account of non-normality of the cost data by using a log-link function. UK unit costs were applied to resource use. The analysis was repeated after multiple imputation for missing data.

RESULTS

Costs incurred by patients who ever relapsed ( pound14,055) during three years were almost double to those incurred by patients who never relapsed ( pound7417). 61% of the cost difference was accounted for by hospital stay. The impact of relapse was even greater in the 1-year cost comparison. Results from the additional analysis with imputed missing data remained largely consistent.

CONCLUSIONS

Our findings confirm the significant economic burden of relapse, and show such costs were mainly due to hospital stay. Nevertheless, the use of UK unit costs requires caution when interpreting this costing in the context of a specific country, as resource use and their associated costs will differ by country.

Cost of treatment of schizophrenia in six European countries

BACKGROUND AND AIMS

As part of an RCT in six European sites, the direct mental health care cost for 422 patients with schizophrenia was analysed according to how total and medication costs differed across sites and which variables were likely to predict total or service-specific costs.

METHOD

Service use was recorded continuously during a 12-month follow-up. Prescribed psychotropic medication was recorded at baseline and 12 months later. Service use data were transformed into EURO, log-transformed and analysed using linear regression models.

RESULTS

Although samples were homogeneous, large inter-site cost differences were found (annual means ranging from 2958 euro in Spain up to 36978 euro in Switzerland). Psychopharmacologic costs were much more constant across sites than costs for other services. Total costs were associated more with region or socio-demographic characteristics than with disorder related parameters.

CONCLUSIONS

The findings confirm remarkable differences in direct costs of patients with schizophrenia across Europe. However, the relative stability of medication costs suggests a need to analyse mechanisms that influence service-specific costs for schizophrenia.

Cost-effectiveness model comparing olanzapine and other oral atypical antipsychotics in the treatment of schizophrenia in the United States

BACKGROUND

Schizophrenia is often a persistent and costly illness that requires continued treatment with antipsychotics. Differences among antipsychotics on efficacy, safety, tolerability, adherence, and cost have cost-effectiveness implications for treating schizophrenia. This study compares the cost-effectiveness of oral olanzapine, oral risperidone (at generic cost, primary comparator), quetiapine, ziprasidone, and aripiprazole in the treatment of patients with schizophrenia from the perspective of third-party payers in the U.S. health care system.

METHODS

A 1-year microsimulation economic decision model, with quarterly cycles, was developed to simulate the dynamic nature of usual care of schizophrenia patients who switch, continue, discontinue, and restart their medications. The model captures clinical and cost parameters including adherence levels, relapse with and without hospitalization, quality-adjusted life years (QALYs), treatment discontinuation by reason, treatment-emergent adverse events, suicide, health care resource utilization, and direct medical care costs. Published medical literature and a clinical expert panel were used to develop baseline model assumptions. Key model outcomes included mean annual total direct cost per treatment, cost per stable patient, and incremental cost-effectiveness values per QALY gained.

RESULTS

The results of the microsimulation model indicated that olanzapine had the lowest mean annual direct health care cost ($8,544) followed by generic risperidone ($9,080). In addition, olanzapine resulted in more QALYs than risperidone (0.733 vs. 0.719). The base case and multiple sensitivity analyses found olanzapine to be the dominant choice in terms of incremental cost-effectiveness per QALY gained.

CONCLUSION

The utilization of olanzapine is predicted in this model to result in better clinical outcomes and lower total direct health care costs compared to generic risperidone, quetiapine, ziprasidone, and aripiprazole. Olanzapine may, therefore, be a cost-effective therapeutic option for patients with schizophrenia.

Decision models in the evaluation of psychotropic drugs : useful tool or useless toy?

A current contribution in the European Journal of Health Economics employs a decision model to compare health care costs of olanzapine and risperidone treatment for schizophrenia. The model suggests that a treatment strategy of first-line olanzapine is cost-saving over a 1-year period, with additional clinical benefits in the form of avoided relapses in the long-term. From a clinical perspective this finding is indubitably relevant, but can physicians and policy makers believe it? The study is presented in a balanced way, assumptions are based on data extracted from clinical trials published in major psychiatric journals, and the theoretical underpinnings of the model are reasonable. Despite these positive aspects, we believe that the methodology used in this study-the decision model approach-is an unsuitable and potentially misleading tool for evaluating psychotropic drugs. In this commentary, taking the olanzapine vs. risperidone model as an example, arguments are provided to support this statement.