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

Cost-effectiveness of recombinant tissue-type plasminogen activator for acute ischaemic stroke with unknown time of onset: a Markov modelling analysis from the Chinese and US perspectives

OBJECTIVE

The effectiveness of MRI-guided intravenous recombinant tissue-type plasminogen activator (r-tPA) for acute ischaemic stroke (AIS) with an unknown time of onset has been demonstrated by the WAKE-UP Trial. We aim to evaluate its long-term cost-effectiveness from the perspective of Chinese and US healthcare payers.

METHODS

A combination of decision tree and Markov model was built to project lifetime costs and quality-adjusted life-years (QALYs) associated with intravenous r-tPA or placebo treatment. Model inputs including the transition probabilities, costs and utilities were derived from the WAKE-UP Trial, similar cost-effectiveness studies and other published sources. To compare intravenous r-tPA to placebo, we calculated incremental costs, incremental QALYs and incremental cost-effectiveness ratio (ICER). One-way sensitivity, probabilistic sensitivity and subgroup analyses were performed to evaluate uncertainty in the results.

RESULTS

In China, intravenous r-tPA gained an additional lifetime QALY of 0.293 with an additional cost of the Chinese Yuan (¥) of 7871 when compared with placebo, resulting in an ICER of ¥26 870 (US$3894)/QALY. In the USA, intravenous r-tPA yielded a higher QALY (difference: 0.430) and lower cost (difference: ¥-4563) when compared with placebo. In probabilistic sensitivity analyses, intravenous r-tPA had a 97.8% and 99.8% probability of being cost-effective or cost-saving in China and the USA, respectively. These findings remained robust under one-way sensitivity and subgroup analysis except for patients with a National Institute of Health Stroke Scale Score of less than 4, between 11 and 16, and over 16.

CONCLUSIONS

MRI-guided intravenous r-tPA for patients with AIS with an unknown time of onset is cost-effective in China and cost-saving in the USA.

Efficacy and safety of rt-PA intravenous thrombolysis in patients with wake-up stroke: A meta-analysis

BACKGROUND

: Recombinant tissue plasminogen activator (rt-PA) is one of the most effective therapies for patients with acute ischemic stroke. However, wake-up stroke (WUS) is typically excluded from intravenous thrombolytic therapy because of the unclear time of symptom onset. Therefore, we aimed to assess the efficacy and safety of rt-PA intravenous thrombolysis in patients with WUS by meta-analysis.

METHODS

: We completed a systematic literature search of PubMed, Embase, the Cochrane Library, and SinoMed and included relevant studies of WUS patients covering rt-PA thrombolysis and nonthrombolysis (published from January 1, 2000, to February 28, 2021, with no language restrictions). The primary outcomes included safety outcomes and functional outcomes. Safety outcomes were measured according to the incidence of symptomatic intracranial hemorrhage and mortality within 90 days. The efficacy outcomes were measured based on 90-day modified Rankin Scale scores. We assessed pooled data using either a random-effects model (when P < .10, I2 > 50%) or a fixed-effects model (when P > .10, I2 < 50%).

RESULTS

: A total of 913 patients from 9 studies were included in the meta-analysis. All patients had ischemic stroke confirmed by computed tomography or magnetic resonance imaging. The incidence of modified Rankin Scale 0 to 2 was significantly higher in the rt-PA thrombolysis group compared with the nonthrombolysis group. And rt-PA thrombolytic WUS patients did not differ significantly from nonthrombolytic WUS patients in terms of 90-day mortality. However, the incidence of Symptomatic intracranial hemorrhage was also significantly higher in the rt-PA thrombolysis group than that in the nonthrombolysis group.

CONCLUSIONS

: Patients with WUS who received rt-PA thrombolysis had a significant positive effect within 90 days. In addition, although there was no significant increase in mortality, we need to be aware of the risk of intracranial hemorrhage transformation associated with rt-PA thrombolysis despite no obvious increase in mortality. The safety of rt-PA intravenous thrombolysis should be closely monitored in patients with WUS.

Cost-Effectiveness of Magnetic Resonance Imaging-Guided Thrombolysis for Patients With Stroke With Unknown Time of Onset

OBJECTIVES

Patients waking up with stroke symptoms are often excluded from intravenous thrombolysis with alteplase (IV-tpa). The WAKE-UP trial, a European multicenter randomized controlled trial, proved the clinical effectiveness of magnetic resonance imaging-guided IV-tpa for these patients. This analysis aimed to assess the cost-effectiveness of the intervention compared to placebo.

METHODS

A Markov model was designed to analyze the cost-effectiveness over a 25-year time horizon. The model consisted of an inpatient acute care phase and a rest-of-life phase. Health states were defined by the modified Rankin Scale (mRS). Initial transition probabilities to mRS scores were based on WAKE-UP data and health state utilities on literature search. Costs were based on data from the University Medical Center Hamburg-Eppendorf, literature, and expert opinion. Incremental costs and effects over the patients' lifetime were estimated. The analysis was conducted from a formal German healthcare perspective. Univariate and probabilistic sensitivity analyses were performed.

RESULTS

Treatment with IV-tpa resulted in cost savings of €51 009 and 1.30 incremental gains in quality-adjusted life-years at a 5% discount rate. Univariate sensitivity analysis revealed incremental cost-effectiveness ratio being sensitive to the relative risk of favorable outcome on mRS for placebo patients after stroke, the costs of long-term care for patients with mRS 4, and patient age at initial stroke event. In all cases, IV-tpa remained cost-effective. Probabilistic sensitivity analysis proved IV-tpa cost-effective in >95% of the simulations results.

CONCLUSIONS

Magnetic resonance imaging-guided IV-tpa compared to placebo is cost-effective in patients with ischemic stroke with unknown time of onset.

Adapting Clinical Practice of Thrombolysis for Acute Ischemic Stroke Beyond 4.5 Hours: A Review of the Literature

Several clinical trials have demonstrated that advanced neuroimaging can select patients for recanalization therapy in an extended time window. The favorable functional outcomes and safety profile of these studies have led to the incorporation of neuroimaging in endovascular treatment guidelines, and most recently, also extended to decision making on thrombolysis. Two randomized clinical trials have demonstrated that patients who are not amenable to endovascular thrombectomy within 4.5 hours from symptoms discovery or beyond 4.5 hours from the last-known-well time may also be safely treated with intravenous thrombolysis and have a clinical benefit above the risk of safety concerns. With the growing aging population, increased stroke incidence in the young, and the impact of evolving medical practice, healthcare and stroke systems of care need to adapt continuously to provide evidence-based care efficiently. Therefore, understanding and incorporating appropriate screening strategies is critical for the prompt recognition of potentially eligible patients for extended-window intravenous thrombolysis. Here we review the clinical trial evidence for thrombolysis for acute ischemic stroke in the extended time window and provide a review of new enrolling clinical trials that include thrombolysis intervention beyond the 4.5 hour window.

Cost-effectiveness of short-protocol emergency brain MRI after negative non-contrast CT for minor stroke detection

Objectives

To investigate the cost-effectiveness of supplemental short-protocol brain MRI after negative non-contrast CT for the detection of minor strokes in emergency patients with mild and unspecific neurological symptoms.

Methods

The economic evaluation was centered around a prospective single-center diagnostic accuracy study validating the use of short-protocol brain MRI in the emergency setting. A decision-analytic Markov model distinguished the strategies “no additional imaging” and “additional short-protocol MRI” for evaluation. Minor stroke was assumed to be missed in the initial evaluation in 40% of patients without short-protocol MRI. Specialized post-stroke care with immediate secondary prophylaxis was assumed for patients with detected minor stroke. Utilities and quality-of-life measures were estimated as quality-adjusted life years (QALYs). Input parameters were obtained from the literature. The Markov model simulated a follow-up period of up to 30 years. Willingness to pay was set to $100,000 per QALY. Cost-effectiveness was calculated and deterministic and probabilistic sensitivity analysis was performed.

Results

Additional short-protocol MRI was the dominant strategy with overall costs of $26,304 (CT only: $27,109). Cumulative calculated effectiveness in the CT-only group was 14.25 QALYs (short-protocol MRI group: 14.31 QALYs). In the deterministic sensitivity analysis, additional short-protocol MRI remained the dominant strategy in all investigated ranges. Probabilistic sensitivity analysis results from the base case analysis were confirmed, and additional short-protocol MRI resulted in lower costs and higher effectiveness.

Conclusion

Additional short-protocol MRI in emergency patients with mild and unspecific neurological symptoms enables timely secondary prophylaxis through detection of minor strokes, resulting in lower costs and higher cumulative QALYs.

Key Points

• Short-protocol brain MRI after negative head CT in selected emergency patients with mild and unspecific neurological symptoms allows for timely detection of minor strokes.

• This strategy supports clinical decision-making with regard to immediate initiation of secondary prophylactic treatment, potentially preventing subsequent major strokes with associated high costs and reduced QALY.

• According to the Markov model, additional short-protocol MRI remained the dominant strategy over wide variations of input parameters, even when assuming disproportionally high costs of the supplemental MRI scan.

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.

Improved detectability of acute and subacute brainstem infarctions by combining standard axial and thin-sliced sagittal DWI

BACKGROUND AND PURPOSE

Most false negative findings in DWI of ischemic stroke are in patients with minor deficits clinically localized to the brainstem. Our goal was to evaluate the benefit of a thin-sliced sagittal DWI in addition to conventional axial DWI at 1.5T for the detection of brainstem infarctions.

METHODS

Data of patients with symptoms consistent with acute and subacute brainstem infarction and an MRI examination including standard axial DWI and thin-sliced sagittal DWI were retrospectively analyzed. Patients with the later diagnosis of a TIA, an inflammation or a tumor of the brainstem were excluded from analysis. Diffusion restrictions were identified by two independent raters blinded for the final clinical diagnosis in three separate reading steps: First, only axial DWI, secondly only sagittal DWI, and lastly both DWIs together. Presence and size of DWI-lesions were documented for each plane. Differences between the observers were settled in consensus in a separate joint reading.

RESULTS

Of 73 included patients, 46 patients were clinically diagnosed with brainstem infarction. Inter-observer agreement was excellent for the detection of brainstem lesions in axial and sagittal DWI (kappa = 0.94 and 0.97). In 28/46 patients (60.9%) lesions were detected in the axial plane alone, whereas in 6 more patients (73.9%) lesions were detected in the review of both sequences together. All lesions undetectable in the axial plane were smaller than 5 mm in cranio-caudal direction.

CONCLUSIONS

Thin-sliced sagittal DWI in addition to axial DWI improves the detection rate of brainstem infarction with little additional expenditure of time.

Safety and cost-effectiveness thrombolysis by diffusion-weighted imaging and fluid attenuated inversion recovery mismatch for wake-up stroke

Wake-up stroke, defined as patients who wake up with stroke symptoms which were not present prior to falling asleep, accounted for 14%-25% of acute ischemic stroke. Due to the unknown time of symptom onset, wake-up stoke was not in including criteria of intravenous thrombolysis. Several large randomized stroke trials using diffusion-weighted imaging(DWI)and fluid attenuated inversion recovery(FLAIR)mismatch patient selection may identify a subset of patients with wake-up stroke that can safely and effectively benefit from intravenous thrombolysis. In addition, economic factor was another important limitation to generalize thrombolysis treatment. Fortunately, MRI-based thrombolysis was a cost-effective treatment for wake-up stroke compared to these patients with no thrombolysis.

Would a Large tPA Trial for Those 4.5 to 6.0 Hours from Stroke Onset Be Good Value for Information?

OBJECTIVES

To quantify the potential value of new research in patients treated with thrombolytic treatment (tissue-type plasminogen activator [tPA]) in the 4.5- to 6.0-hour time window after stroke onset and to determine the optimal size of a future trial using value of information analysis.

METHODS

Expected value of partial perfect and sample information (EVPPI and EVSI) analyses were conducted using a probabilistic Markov model. Data for modified Rankin Scale (mRS) distributions in patients 4.5 to 6.0 hours since stroke onset for tPA (n = 576) and placebo (n = 543) were obtained from pooled randomized controlled trials. EVSI was quantified with net monetary benefit (assuming willingness to pay for health as $100,000/QALY). We calculated discounted population-level EVSI by multiplying per-person EVSI by the annual number of eligible patients with stroke in the United States and assuming a 10-year time frame of treatment use. Study costs were based on administrative costs and the costs of tPA.

RESULTS

The base-case lifetime cost-effectiveness analysis showed that tPA was dominated by placebo in this patient group. EVPPI for mRS distributions was $1003 per person. On the basis of EVSI, the optimal sample size of a new trial collecting data on tPA efficacy in these patients would be 5600 across study arms with expected population-level societal returns (EVSI minus study costs) of $68.7 million.

CONCLUSIONS

Expanding research attention to the 4.5- to 6.0-hour time window for tPA treatment of patients with acute ischemic stroke is justified because the expected returns are substantial. Even a relatively large trial in which more information on treatment efficacy on the basis of mRS scores is collected would represent good value for information.

MR imaging in hyperacute ischemic stroke

Brain and vascular imaging are required components of the emergency assessment of patients with suspected stroke. Either CT or MRI may be used as the initial imaging test. MRI is more sensitive to the presence of acute and chronic ischemic lesions, and chronic microbleeds, but CT remains the most practical and used initial brain imaging test. Although, a non-enhanced CT or T2* MRI sequence showing no haemorrhage is sufficient for deciding intravenous treatment eligibility within the first 4.5h after stroke onset, a non-invasive intracranial vascular study is strongly recommended during the initial imaging evaluation of the acute stroke patient, particularly if mechanical thrombectomy is contemplated. Advanced imaging with multimodal MRI may facilitate accurate ischemic stroke diagnosis and characterization, and should be considered as an alternative to CT, especially for the selection of patients for acute reperfusion therapy in extended time windows, and in patients in which time of stroke onset is unknown. However, MRI should only be considered in the acute stroke workflow if centres are able to achieve speed and triaging efficiency similar to that which is currently available with CT-based imaging.