Model-based cost-effectiveness analyses for the treatment of acute stroke events: a review and summary of challenges

Secondary Prevention via Case Managers in Stroke Patients: A Cost-Effectiveness Analysis of Claims Data from German Statutory Health Insurance Providers

Strokes remain a leading cause of death and disability worldwide. The STROKE OWL study evaluated a novel case management approach for patients with stroke (modified Rankin Scale 0-4) or transient ischemic attack (TIA) who received support across healthcare settings and secondary prevention training from case managers for one year. The primary aim of this quasi-experimental study was a reduction in stroke recurrence. Here, we report the results of a health economic analysis of the STROKE OWL study, conducted in accordance with CHEERS guidelines. The calculations were based on claims data of cooperating statutory health insurance companies. In addition to a regression analysis for cost comparison, the incremental cost-effectiveness ratio was determined, and a probabilistic sensitivity analysis was carried out. In total, 1167 patients per group were included in the analysis. The intervention group incurred 32.3% higher direct costs (p < 0.001) than the control group. With a difference of EUR 1384.78 (95% CI: [1.2384-1.4143], p < 0.0001) and a 5.32% increase in hazards for the intervention group (HR = 1.0532, 95% CI: [0.7869-1.4096], p = 0.7274) resulting in an ICER of EUR 260.30, we found that the case management intervention dominated in the total stroke population, even for an arbitrarily high willingness to pay. In the TIA subgroup, however, the intervention was cost-effective even for a low willingness to pay. Our results are limited by small samples for both TIA and severe stroke patients and by claims data heterogeneity for some cost components, which had to be excluded from the analysis. Future research should investigate the cost-effectiveness of case management interventions for both severe stroke and TIA populations using appropriate data.

Stroke rehabilitation pathways during the first year: A cost-effectiveness analysis from a cohort of 460 individuals

BACKGROUND

Stroke burden challenges global health, and social and economic policies. Although stroke recovery encompasses a wide range of care, including in-hospital, outpatient, and community-based rehabilitation, there are no published cost-effectiveness studies of integrated post-stroke pathways.

OBJECTIVE

To determine the most cost-effective rehabilitation pathway during the first 12 months after a first-ever stroke.

METHODS

A cohort of people in the acute phase of a first stroke was followed after hospital discharge; 51 % women, mean (SD) age 74.4 (12.9) years, mean National Institute of Health Stroke Scale score 11.7 (8.5) points, and mode modified Rankin Scale score 3 points. We developed a decision tree model of 9 sequences of rehabilitation care organised in 3 stages (3, 6 and 12 months) through a combination of public, semi-public and private entities, considering both the individual and healthcare service perspectives. Health outcomes were expressed as quality-adjusted life years (QALY) over a 1-year time horizon. Costs included healthcare, social care, and productivity losses. Sensitivity analyses were conducted on model input values.

RESULTS

From the individual perspective, pathway 3 (Short-term Inpatient Unit » Community Clinic) was the most cost-effective, followed by pathway 1 (Rehabilitation Centre » Community Clinic). From the healthcare service perspective, pathway 3 was the most cost-effective followed by pathway 7 (Outpatient Hospital » Private Clinic). All other pathways were considered strongly dominated and excluded from the analysis. The total 1-year mean cost ranged between €12104 and €23024 from the individual's perspective and between €10992 and €31319 from the healthcare service perspective.

CONCLUSION

Assuming a willingness-to-pay threshold of one times the national gross domestic product (€20633/QALY), pathway 3 (Short-term Inpatient Unit » Community Clinic) was the most cost-effective strategy from both the individual and healthcare service perspectives. Rehabilitation pathway data contribute to the development of a future integrated care system adapted to different stroke profiles.

Cost-effectiveness of endovascular thrombectomy in acute stroke patients with large ischemic core

BACKGROUND

Evidence has shown that endovascular thrombectomy (EVT) treatment improves clinical outcomes. Yet, its benefit remains uncertain in patients with large established infarcts as defined by ASPECTS (Alberta Stroke Program Early CT Score) <6. This study evaluates the cost-effectiveness of EVT, compared with standard care (SC), in acute ischemic stroke (AIS) patients with ASPECTS 3-5.

METHODS

An economic evaluation study was performed combining a decision tree and Markov model to estimate lifetime costs (2021 US$) and quality-adjusted life years (QALYs) of AIS patients with ASPECTS 3-5. Incremental cost-effectiveness ratios (ICERs), net monetary benefits (NMBs), and deterministic one-way and two-way sensitivity analyses were performed. Probabilistic sensitivity analyses were also performed to evaluate the robustness of our model.

RESULTS

Compared with SC, the cost-effectiveness analyses revealed that EVT yields higher lifetime benefits (2.20 QALYs vs 1.41 QALYs) with higher lifetime healthcare cost per patient ($285 861 vs $272 954). The difference in health benefits between EVT and SC was 0.79 QALYs, equivalent to 288 additional days of healthy life per patient. Even though EVT is more costly than SC alone, it is still cost-effective given better outcomes with ICER of $16 239/QALY. The probabilistic sensitivity analyses indicated that EVT was the most cost-effective strategy in 98.8% (9882 of 10 000) of iterations at the willingness-to-pay threshold of $100 000 per QALY.

CONCLUSIONS

The results of this study suggest that EVT is cost-effective in AIS patients with a large ischemic core (ASPECTS 3-5), compared with SC alone over the patient's lifetime.

Cost-effectiveness of ticagrelor plus aspirin versus aspirin in acute ischaemic stroke or transient ischaemic attack: an economic evaluation of the THALES trial

Objective

THALES demonstrated that ticagrelor plus aspirin reduced the risk of stroke or death but increased bleeding versus aspirin during the 30 days following a mild-to-moderate acute non-cardioembolic ischaemic stroke (AIS) or high-risk transient ischaemic attack (TIA). There are no cost-effectiveness analyses supporting this combination in Europe. To address this, a cost-effectiveness analysis was performed.

Methods

Cost-effectiveness was evaluated using a decision tree and Markov model with a short-term and long-term (30-year) horizon. Stroke, mortality, bleeding and EuroQol-5 Dimension (EQ-5D) data from THALES were used to estimate short-term outcomes. Model transitions were based on stroke severity (disabling stroke was defined as modified Rankin Scale >2). Healthcare resource utilisation and EQ-5D data beyond 30 days were based on SOCRATES, another trial in AIS/TIA that compared ticagrelor with aspirin. Long-term costs, survival and disutilities were based on published literature. Unit costs were derived from national databases and discounted at 3% annually from a Swedish healthcare perspective.

Results

One-month treatment with ticagrelor plus aspirin resulted in 12 fewer strokes, 4 additional major bleeds and cost savings of €95 000 per 1000 patients versus aspirin from a Swedish healthcare perspective. This translated into increased quality-adjusted life-years (0.04) and reduced societal costs (-€1358) per patient over a lifetime horizon. Key drivers of cost-effectiveness were number of patients experiencing subsequent disabling stroke and degree of disability. Findings were robust over a range of input assumptions.

Conclusion

One month of treatment with ticagrelor plus aspirin is likely to improve outcomes and reduce costs versus aspirin in mild-to-moderate AIS or high-risk TIA.

Trial registration number

NCT03354429.

Cost-Effectiveness Study of Initial Imaging Selection in Acute Ischemic Stroke Care

PURPOSE

National guidelines recommend prompt identification of candidates for acute ischemic stroke (AIS) treatment, requiring timely neuroimaging with CT and/or MRI. CT is often preferred because of its widespread availability and rapid acquisition. Despite higher diagnostic accuracy of MRI, it commonly involves complex workflows that could potentially cause treatment time delays. The purpose of this study was to analyze the impact on outcomes of imaging utilization before treatment decisions at comprehensive stroke centers for patients presenting with suspected AIS in the anterior circulation with last-known-well-to-arrival time 0 to 24 hours.

METHODS

A decision simulation model based on the American Heart Association's recommendations for AIS care pathways was developed from a health care perspective to compare initial imaging strategies: (1) stepwise-CT: noncontrast CT (NCCT) at the time of presentation, with CT angiography (CTA) ± CT perfusion (CTP) only in select patients (initial imaging to exclude hemorrhage and extensive ischemia) for mechanical thrombectomy (MT) evaluation; (2) stepwise-hybrid: NCCT at the time of presentation, with MR angiography (MRA) ± MR perfusion (MRP) only for MT evaluation; (3) stepwise-advanced: NCCT + CTA at presentation, with MR diffusion-weighted imaging (MR DWI) + MRP only for MT evaluation; (4) comprehensive-CT: NCCT + CTA + CTP at the time of presentation; and (5) comprehensive-MR: MR DWI + MRA + MRP at the time of presentation. Model parameters were defined using evidence-based data. Cost-effectiveness and sensitivity analyses were performed.

RESULTS

The cost-effectiveness analyses revealed that comprehensive-CT and comprehensive-MR yield the highest lifetime quality-adjusted life-years (QALYs) (4.81 and 4.82, respectively). However, the incremental cost-effectiveness ratio of comprehensive-MR is $233,000/QALY compared with comprehensive-CT. Stepwise-CT, stepwise-hybrid, and stepwise-advanced strategies are dominated, yielding lower QALYs and higher costs compared with comprehensive-CT.

CONCLUSIONS

Performing comprehensive-CT at presentation is the most cost-effective initial imaging strategy at comprehensive stroke centers.

Poststroke Cognitive Impairment in Model-Based Economic Evaluation: A Systematic Review

INTRODUCTION

Cognitive impairment (CI) is a frequent consequence of stroke and is associated with increased costs and reduced quality of life. However, its inclusion in model-based economic evaluation for stroke is limited.

OBJECTIVE

To identify, review, and critically appraise current models of stroke for use in economic evaluation, and to identify applicability to modeling poststroke CI.

METHODS

PubMed, EMBASE, and the NHS Economic Evaluations Database (NHS EED) were systematically searched for papers published from January 2008 to August 2018. Studies that described the development or design of a model of stroke progression intended for use in economic evaluation were included. Abstracts were screened, followed by full text review of potentially relevant articles. Models that included CI were retained for data extraction, and among the remainder, models that included both stroke recurrence and disability were also retained. Relevance and potential for adaptation for modeling CI were assessed using a standard questionnaire.

RESULTS

Forty modeling studies were identified and categorized into 4 groups: Markov disability/recurrence (k = 29); CI (k = 2); discrete event simulation (k = 4), and other (k = 5). Only 2 modeling studies included CI as an outcome, and both focused on narrow populations at risk of intracranial aneurysm. None of the models allowed for disease progression in the absence of a stroke recurrence. None of the included studies carried out any sensitivity analysis in relation to model design or structure.

CONCLUSIONS

Current stroke models used in economic evaluation are not adequate to model poststroke CI or dementia, and will require adaptation to be used for this purpose.

Can Pay-for Performance Incentive Levels be Determined Using a Cost-Effectiveness Framework?

BACKGROUND

Healthcare payers in the United States are increasingly tying provider payments to quality and value using pay-for-performance policies. Cost-effectiveness analysis quantifies value in healthcare but is not currently used to design or prioritize pay-for-performance strategies or metrics. Acute ischemic stroke care provides a useful application to demonstrate how simulation modeling can be used to determine cost-effective levels of financial incentives used in pay-for-performance policies and associated challenges with this approach.

METHODS AND RESULTS

Our framework requires a simulation model that can estimate quality-adjusted life years and costs resulting from improvements in a quality metric. A monetary level of incentives can then be back-calculated using the lifetime discounted quality-adjusted life year (which includes effectiveness of quality improvement) and cost (which includes incentive payments and cost offsets from quality improvements) outputs from the model. We applied this framework to an acute ischemic stroke microsimulation model to calculate the difference in population-level net monetary benefit (willingness-to-pay of $50 000 to $150 000/quality-adjusted life year) accrued under current Medicare policy (stroke payment not adjusted for performance) compared with various hypothetical pay-for-performance policies. Performance measurement was based on time-to-thrombolytic treatment with tPA (tissue-type plasminogen activator). Compared with current payment, equivalent population-level net monetary benefit was achieved in pay-for-performance policies with 10-minute door-to-needle time reductions (5057 more acute ischemic stroke cases/y in the 0-3-hour window) incentivized by increasing tPA payment by as much as 18% to 44% depending on willingness-to-pay for health.

CONCLUSIONS

Cost-effectiveness modeling can be used to determine the upper bound of financial incentives used in pay-for-performance policies, although currently, this approach is limited due to data requirements and modeling assumptions. For tPA payments in acute ischemic stroke, our model-based results suggest financial incentives leading to a 10-minute decrease in door-to-needle time should be implemented but not exceed 18% to 44% of current tPA payment. In general, the optimal level of financial incentives will depend on willingness-to-pay for health and other modeling assumptions around parameter uncertainty and the relationship between quality improvements and long-run quality-adjusted life expectancy and costs.

Validation and calibration of structural models that combine information from multiple sources

INTRODUCTION

Mathematical models that attempt to capture structural relationships between their components and combine information from multiple sources are increasingly used in medicine. Areas covered: We provide an overview of methods for model validation and calibration and survey studies comparing alternative approaches. Expert commentary: Model validation entails a confrontation of models with data, background knowledge, and other models, and can inform judgments about model credibility. Calibration involves selecting parameter values to improve the agreement of model outputs with data. When the goal of modeling is quantitative inference on the effects of interventions or forecasting, calibration can be viewed as estimation. This view clarifies issues related to parameter identifiability and facilitates formal model validation and the examination of consistency among different sources of information. In contrast, when the goal of modeling is the generation of qualitative insights about the modeled phenomenon, calibration is a rather informal process for selecting inputs that result in model behavior that roughly reproduces select aspects of the modeled phenomenon and cannot be equated to an estimation procedure. Current empirical research on validation and calibration methods consists primarily of methodological appraisals or case-studies of alternative techniques and cannot address the numerous complex and multifaceted methodological decisions that modelers must make. Further research is needed on different approaches for developing and validating complex models that combine evidence from multiple sources.

Cost-effectiveness of stent-retriever thrombectomy in combination with IV t-PA compared with IV t-PA alone for acute ischemic stroke in the UK

OBJECTIVE

To evaluate the cost-effectiveness of neurothrombectomy with a stent retriever (Solitaire * Revascularization Device) in treating acute ischemic stroke patients from the UK healthcare provider perspective.

METHODS

A Markov model was developed to simulate health outcomes and costs of two therapies over a lifetime time horizon: stent-retriever thrombectomy in combination with intravenous tissue-type plasminogen activator (IV t-PA), and IV t-PA alone. The model incorporated an acute phase (0-90 days) and a rest of life phase (90+ days). Health states were defined by the modified Rankin Scale score. During the rest of life phase, patients remained in the same health state until a recurrent stroke or death. Clinical effectiveness and safety data were taken from the SWIFT PRIME study. Resource use and health state utilities were informed by published data.

RESULTS

Combined stent-retriever thrombectomy and IV t-PA led to improved quality-of-life and increased life expectancy compared to IV t-PA alone. The higher treatment costs associated with the use of stent-retriever thrombectomy were offset by long-term cost savings due to improved patient health status, leading to overall cost savings of £33 190 per patient and a net benefit of £79 402. Deterministic and probabilistic sensitivity analyses demonstrated that the results were robust to a wide range of parameter inputs.

LIMITATIONS

The acute and long-term costs resource use data were taken from a study based on a patient population that was older and may have had additional comorbidities than the SWIFT PRIME population, resulting in costs that may not be representative of the cohort within this model. In addition, the estimates may not reflect stroke care today as no current evidence is available; however, the cost estimates were deemed reasonable by clinical opinion.

CONCLUSIONS

Combined stent-retriever neurothrombectomy and IV t-PA is a cost-effective treatment for acute ischemic stroke compared with IV t-PA alone.

Modeling the Cost Effectiveness of Neuroimaging-Based Treatment of Acute Wake-Up Stroke

BACKGROUND

Thrombolytic treatment (tissue-type plasminogen activator [tPA]) is only recommended for acute ischemic stroke patients with stroke onset time <4.5 hours. tPA is not recommended when stroke onset time is unknown. Diffusion-weighted MRI (DWI) and fluid attenuated inversion recovery (FLAIR) MRI mismatch information has been found to approximate stroke onset time with some accuracy. Therefore, we developed a micro-simulation model to project health outcomes and costs of MRI-based treatment decisions versus no treatment for acute wake-up stroke patients.

METHODS AND FINDINGS

The model assigned simulated patients a true stroke onset time from a specified probability distribution. DWI-FLAIR mismatch estimated stroke onset <4.5 hours with sensitivity and specificity of 0.62 and 0.78, respectively. Modified Rankin Scale (mRS) scores reflected tPA treatment effectiveness accounting for patients' true stroke onset time. Discounted lifetime costs and benefits (quality-adjusted life years [QALYs]) were projected for each strategy. Incremental cost-effectiveness ratios (ICERs) were calculated for the MRI-based strategy in base-case and sensitivity analyses. With no treatment, 45.1% of simulated patients experienced a good stroke outcome (mRS score 0-1). Under the MRI-based strategy, in which 17.0% of all patients received tPA despite stroke onset times >4.5 hours, 46.3% experienced a good stroke outcome. Lifetime discounted QALYs and costs were 5.312 and $88,247 for the no treatment strategy and 5.342 and $90,869 for the MRI-based strategy, resulting in an ICER of $88,000/QALY. Results were sensitive to variations in patient- and provider-specific factors such as sleep duration, hospital travel and door-to-needle times, as well as onset probability distribution, MRI specificity, and mRS utility values.

CONCLUSIONS

Our model-based findings suggest that an MRI-based treatment strategy for this population could be cost-effective and quantifies the impact that patient- and provider-specific factors, such as sleep duration, hospital travel and door-to-needle times, could have on the optimal decision for wake-up stroke patients.

Burden of stroke in Italy: an economic model highlights savings arising from reduced disability following thrombolysis

BACKGROUND

The consequences of stroke must be assessed not only in terms of incidence and mortality rates, but also in terms of disability, which may persist long after the acute phase. Thrombolysis, if timely administered, can effectively reduce post-stroke disability.

AIMS

The economic model presented herein aims to evaluate, in eligible patients, the effects of alteplase on post-stroke disability and related costs over three-years.

METHODS

The economic analysis was developed on the basis of four key components: clinical outcomes from international trials, economic consequences extracted from cost of illness studies, regulatory data from national and international agencies, and national epidemiological data. A population-level model estimated the difference in disability costs between patients treated with standard care versus those receiving thrombolytic therapy within 4×5 h of acute ischemic stroke. The analysis covered 36 months from discharge.

RESULTS

Reduced costs related to post-stroke disability were observed in treated patients compared with those receiving standard care (control). The overall savings were €2330×15 per average patient: €1445×81 during the first 18 months, €362×25 between 18 and 24 months, and €522×09 in the 24-36 months period. The overall savings on 3174 Italian treated patients in 2013 were €7 395 907 over three-years.

CONCLUSION

Our study reveals that performing thrombolytic therapy in eligible patients improves economic outcomes compared with patients receiving standard care. This model is useful for decision makers, both within and outside of the Italian national context, as a tool to assess the cost-effectiveness of thrombolysis in both short- and long-term period.

Cost effectiveness of rivaroxaban for stroke prevention in German patients with atrial fibrillation

OBJECTIVE

The aim of this study was to assess the cost effectiveness of the novel fixed-dose anticoagulant rivaroxaban compared with the current standard of care, warfarin, for the prevention of stroke in patients with atrial fibrillation (AF).

METHODS

A Markov model was constructed to model the costs and health outcomes of both treatments, potential adverse events, and resulting health states over 35 years. Analyses were based on a hypothetical cohort of 65-year-old patients with non-valvular AF at moderate to high risk of stroke. The main outcome measure was cost per quality-adjusted life-year (QALY) gained over the lifetime, and was assessed from the German Statutory Health Insurance (SHI) perspective. Costs and utility data were drawn from public data and the literature, while event probabilities were derived from both the literature and rivaroxaban's pivotal ROCKET AF trial.

RESULTS

Stroke prophylaxis with rivaroxaban offers health improvements over warfarin treatment at additional cost. From the SHI perspective, at baseline the incremental cost-effectiveness ratio of rivaroxaban was <euro>15,207 per QALY gained in 2014. The results were robust to changes in the majority of variables; however, they were sensitive to the price of rivaroxaban, the hazard ratios for stroke and intracranial hemorrhage, the time horizon, and the discount rate.

CONCLUSIONS

Our results showed that the substantially higher medication costs of rivaroxaban were offset by mitigating the shortcomings of warfarin, most notably frequent dose regulation and bleeding risk. Future health economic studies on novel oral anticoagulants should evaluate the cost effectiveness for secondary stroke prevention and, as clinical data from direct head-to-head comparisons become available, new anticoagulation therapies should be compared against each other.

Direct Costs of Patients With Stroke Can Be Continuously Monitored on a National Level

Background and Purpose—

Treatment of stroke consumes a significant portion of all healthcare expenditure. We developed a system for monitoring costs from individual patient data on a national level in Finland.

Methods—

Multiple national administrative registers were linked to gain episode-of-care data on all hospital-treated patients with incident stroke over the years 1999 to 2007 (n=94 316). Inpatient and specialist outpatient costs were evaluated with a cost database, long-term care costs with fixed prices, and medication costs with true retail prices.

Results—

For the patients of Year 2007, the mean 1-year costs after an ischemic stroke were $29 580, after an intracerebral hemorrhage $36 220, and after a subarachnoid hemorrhage $42 570, valued in Year 2008 US dollars. Only part of these costs are attributable to stroke, because the annual costs prior to stroke were significant, $8900 before ischemic stroke, $7600 before intracerebral hemorrhage, and $4200 before subarachnoid hemorrhage. Older patients with ischemic stroke, and, among patients with ischemic stroke and subarachnoid hemorrhage, women, incurred higher costs. The mean estimated lifetime costs were $130 000 after ischemic stroke or intracerebral hemorrhage and $80 000 after subarachnoid hemorrhage. Annually $1.6 billion is spent in the care of Finnish patients with stroke, which equals to 7% of the national healthcare expenditure, or 0.6% of the gross domestic product. Costs of patients with stroke are increasing with prolonged survival and the aging population.

Conclusions—

Treatment of patients with stroke is a large national investment. Setting up a nationwide system for continuous monitoring of stroke costs is feasible. Cost data should optimally be evaluated in conjunction with effectiveness and performance indicators.

Cost-effectiveness of CT perfusion for selecting patients for intravenous thrombolysis: a US hospital perspective

BACKGROUND AND PURPOSE

Improved selection of patients with stroke for IV tPA treatment may enhance clinical outcomes. Given the limited availability of MR imaging in hospitals, we examined the cost-effectiveness of adding CTP to the usual CT-based methods for selecting patients on the basis of the presence and extent of penumbra.

MATERIALS AND METHODS

A decision-analytic model estimated the costs and outcomes associated with penumbra-based CTP selection in a patient population similar to that enrolled in the IV tPA clinical trials. Model inputs were obtained from published literature, clinical trial data, standard US costing sources, and expert opinion. Cost per life-year saved and cost per QALY gained were estimated from a hospital perspective.

RESULTS

Addition of penumbra-based CTP to standard unenhanced CT improved favorable outcome (mRS, ≤1) by 0.59% and reduced cost by $42 compared with selection based on unenhanced CT alone. Life-years and QALYs improved. Multivariate sensitivity analysis predicted cost-effectiveness (≤$50,000 per QALY) in 89.2% of simulation runs.

CONCLUSIONS

Using penumbra-based CTP after routine CT to select patients with ischemic stroke for IV tPA is cost-effective compared with the usual CT-based methods for hospitals. With the ease of access of CTP, penumbra-based selection methods may be readily available to hospitals. Thus, this economic analysis may lend further support to the consideration of a paradigm shift in acute stroke evaluation.