scholarly journals Estimating the Expected Value of Sample Information across Different Sample Sizes Using Moment Matching and Nonlinear Regression

2019 ◽  
Vol 39 (4) ◽  
pp. 347-359 ◽  
Author(s):  
Anna Heath ◽  
Ioanna Manolopoulou ◽  
Gianluca Baio
Keyword(s):  
Health Economic ◽  
Nonlinear Regression ◽  
Economic Model ◽  
Trial Design ◽  
Expected Value ◽  
Moment Matching ◽  
Sample Sizes ◽  
Sample Information ◽  
Health Economic Model ◽  
The Cost

Background. The expected value of sample information (EVSI) determines the economic value of any future study with a specific design aimed at reducing uncertainty about the parameters underlying a health economic model. This has potential as a tool for trial design; the cost and value of different designs could be compared to find the trial with the greatest net benefit. However, despite recent developments, EVSI analysis can be slow, especially when optimizing over a large number of different designs. Methods. This article develops a method to reduce the computation time required to calculate the EVSI across different sample sizes. Our method extends the moment-matching approach to EVSI estimation to optimize over different sample sizes for the underlying trial while retaining a similar computational cost to a single EVSI estimate. This extension calculates the posterior variance of the net monetary benefit across alternative sample sizes and then uses Bayesian nonlinear regression to estimate the EVSI across these sample sizes. Results. A health economic model developed to assess the cost-effectiveness of interventions for chronic pain demonstrates that this EVSI calculation method is fast and accurate for realistic models. This example also highlights how different trial designs can be compared using the EVSI. Conclusion. The proposed estimation method is fast and accurate when calculating the EVSI across different sample sizes. This will allow researchers to realize the potential of using the EVSI to determine an economically optimal trial design for reducing uncertainty in health economic models. Limitations. Our method involves rerunning the health economic model, which can be more computationally expensive than some recent alternatives, especially in complex models.

scholarly journals Calculating the Expected Value of Sample Information in Practice: Considerations from 3 Case Studies

2020 ◽  
Vol 40 (3) ◽  
pp. 314-326 ◽  
Author(s):  
Anna Heath ◽  
Natalia Kunst ◽  
Christopher Jackson ◽  
Mark Strong ◽  
Fernando Alarid-Escudero ◽  
...  
Keyword(s):  
Health Economic ◽  
Monte Carlo ◽  
Sample Size ◽  
Economic Model ◽  
Expected Value ◽  
Monte Carlo Algorithm ◽  
Approximation Methods ◽  
Sample Sizes ◽  
Sample Information ◽  
Health Economic Model

Background. Investing efficiently in future research to improve policy decisions is an important goal. Expected value of sample information (EVSI) can be used to select the specific design and sample size of a proposed study by assessing the benefit of a range of different studies. Estimating EVSI with the standard nested Monte Carlo algorithm has a notoriously high computational burden, especially when using a complex decision model or when optimizing over study sample sizes and designs. Recently, several more efficient EVSI approximation methods have been developed. However, these approximation methods have not been compared, and therefore their comparative performance across different examples has not been explored. Methods. We compared 4 EVSI methods using 3 previously published health economic models. The examples were chosen to represent a range of real-world contexts, including situations with multiple study outcomes, missing data, and data from an observational rather than a randomized study. The computational speed and accuracy of each method were compared. Results. In each example, the approximation methods took minutes or hours to achieve reasonably accurate EVSI estimates, whereas the traditional Monte Carlo method took weeks. Specific methods are particularly suited to problems where we wish to compare multiple proposed sample sizes, when the proposed sample size is large, or when the health economic model is computationally expensive. Conclusions. As all the evaluated methods gave estimates similar to those given by traditional Monte Carlo, we suggest that EVSI can now be efficiently computed with confidence in realistic examples. No systematically superior EVSI computation method exists as the properties of the different methods depend on the underlying health economic model, data generation process, and user expertise.

scholarly journals A health economic model to assess the cost-effectiveness of OPTIFAST for the treatment of obesity in the United States

2018 ◽  
Vol 21 (9) ◽  
pp. 835-844 ◽  
Author(s):  
Mark Nuijten ◽  
Agnieszka Marczewska ◽  
Krysmaru Araujo Torres ◽  
Bahareh Rasouli ◽  
Moreno Perugini
Keyword(s):  
United States ◽  
Health Economic ◽  
Cost Effectiveness ◽  
Economic Model ◽  
The United States ◽  
Health Economic Model ◽  
Treatment Of Obesity ◽  
The Cost

scholarly journals Expected Value of Sample Information to Guide the Design of Group Sequential Clinical Trials

2021 ◽  
pp. 0272989X2110450
Author(s):  
Laura Flight ◽  
Steven Julious ◽  
Alan Brennan ◽  
Susan Todd
Keyword(s):  
Health Economic ◽  
Cost Effectiveness ◽  
Expected Value ◽  
Stopping Rule ◽  
Adaptive Designs ◽  
Net Benefit ◽  
Group Sequential ◽  
Sample Information ◽  
The Cost

Introduction Adaptive designs allow changes to an ongoing trial based on prespecified early examinations of accrued data. Opportunities are potentially being missed to incorporate health economic considerations into the design of these studies. Methods We describe how to estimate the expected value of sample information for group sequential design adaptive trials. We operationalize this approach in a hypothetical case study using data from a pilot trial. We report the expected value of sample information and expected net benefit of sampling results for 5 design options for the future full-scale trial including the fixed-sample-size design and the group sequential design using either the Pocock stopping rule or the O’Brien-Fleming stopping rule with 2 or 5 analyses. We considered 2 scenarios relating to 1) using the cost-effectiveness model with a traditional approach to the health economic analysis and 2) adjusting the cost-effectiveness analysis to incorporate the bias-adjusted maximum likelihood estimates of trial outcomes to account for the bias that can be generated in adaptive trials. Results The case study demonstrated that the methods developed could be successfully applied in practice. The results showed that the O’Brien-Fleming stopping rule with 2 analyses was the most efficient design with the highest expected net benefit of sampling in the case study. Conclusions Cost-effectiveness considerations are unavoidable in budget-constrained, publicly funded health care systems, and adaptive designs can provide an alternative to costly fixed-sample-size designs. We recommend that when planning a clinical trial, expected value of sample information methods be used to compare possible adaptive and nonadaptive trial designs, with appropriate adjustment, to help justify the choice of design characteristics and ensure the cost-effective use of research funding. Highlights Opportunities are potentially being missed to incorporate health economic considerations into the design of adaptive clinical trials. Existing expected value of sample information analysis methods can be extended to compare possible group sequential and nonadaptive trial designs when planning a clinical trial. We recommend that adjusted analyses be presented to control for the potential impact of the adaptive designs and to maintain the accuracy of the calculations. This approach can help to justify the choice of design characteristics and ensure the cost-effective use of limited research funding.

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