how to integrate external evidence into within trial economic evaluations? mohsen sadatsafavi md,...
TRANSCRIPT
How to integrate external evidence into within trial economic evaluations?
Mohsen Sadatsafavi MD, PhDUniversity of British Columbia
2015.04.13
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Conflict of Interest
No apparent or perceived conflict of interest
Received CIHR fellow-ship award for this work
All interpretations are my own
Our TeamCarlo Marra, Shawn Aaron, Stirling Bryan
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Outline
• A novel method for incorporating external evidence in economic evaluations
• Context in which it is applicable• What it does• A running example• Pros + Cons + conclusions
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Economic trialsas vehicles for evaluations
• Model-based evaluations• Evidence is ‘parameterized’ and fed into a computer
program (mathematical function)
• simulation
• Trial-based evaluations• Individuals are assigned to competing treatments and
their experiences is represented through cost and effectiveness values
• (bivariate) statistical inference• bootstrap as s popular paradigm
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Issues with trial-based CEAs
Failure to compare all available options
A truncated time horizon
Lack of relevance to the jurisdiction of interest
Failure to incorporate all evidence the most damning criticism
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ContextAn example: OPTIMAL trial in COPD
• Mono, double, and triple inhaler therapy in COPD (T1, T2, T3)
• N=442• Follow-up 1 year• Primary outcome: exacerbation rate• Prospective economic evaluation component• Results
– RR of T2 v. T1: 1.01 (0.59 – 0.73)– RR of T3 v. T1: 0.84 (0.47 – 1.49)
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ContextOPTIMAL CEA
• Sequence of imputation, regression, outcome calculations within a bootstrap envelope
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Trialist versus economist
Treatment effects (RR=0.84, NS) ICER=243K
Pooled estimate
Regression-based methods Bootstrap methods
OPTIMAL trial
Trialist Economist
Decision maker
Welte et. al. T3 v. T1
RR=0.38 (0.28 – 0.57)
Meta-analyst
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CONTEXTReconciling external evidence in RCT-based CEAs
Desist RCT-based CEA and resort to model-based evaluation Paradigm shift
Switch to parametric Bayesian evidence synthesisMCMC using WinBUGS (technical, lots of programing, model
convergence etc) Off-putting
Stay with the bootstrap-based methods, incorporate external evidence
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MethodsRCT-CEA without external evidence
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MethodsRCT-CEA with external evidence
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ResultsCase study in COPD
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ResultsCase study in COPD
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Conclusions
• Theoretically, possible to use trials as ‘vehicle’ for evidence synthesis, yet avoid the ‘most damning criticism’
• Practically, with too many parameters, it can be computationally prohibitive
• Best use is in sensitivity and secondary analyses• What if we incorporate the results of the study by xyz?
• The experts in our team believe it is almost impossible that chemo+radiation increases the risk of metastasis ->half-flat priors
FacultyMohsen SadatsafaviJ Mark FitzGeraldStirling BryanLarry Lynd
Research StaffHamid TavakoliTania ConteRoxanne Rousseau
StudentsZafar ZafariWenjia Chen
Thank You!
Respiratory Evaluation Sciences Program (resp.med.ubc.ca)