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Title: Expected survival time as a summary statistic in economic analysis and evidence synthesis
Author: Guyot, Patricia Danielle Marie
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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The objective of this thesis was to explore and contribute to improve the use of studies reporting survival outcomes in cost-effectiveness analysis and evidence syntheses. A review of the literature was undertaken to compare and contrast methods commonly used to assess effectiveness and cost-effectiveness for survival outcomes. A method that re-creates sufficient statistics from published Kaplan-Meier curves was developed to allow re-analysis of published survival results. Finally, a new approach to modelling that allows external information on various different survival metrics to be combined with trial data were developed and illustrated with an example. The literature review highlighted that in numerous health technology assessments, survival outcomes were not analysed in a single, coherent analysis, but instead by two separate models: a parametric model was fitted to the standard treatment and a hazard ratio estimated from another model was then applied to this baseline in order to generate the treatment arm. To improve this current state of methodology, we found that KM data for each arm of the RCT could be reliably reconstructed from the published survival curves, by using a simple algorithm based on the inverted KM equations and the information on numbers at risk reported alongside KM curves and/or the total number of events reported. The KM data of one RCT on patients with head and neck cancer were re-created and then used to illustrate the new methods developed for the extrapolation of RCT data using external data. A US cancer database (SEER), mortality statistics from the general population and expert opinion were used to impose constraints on overall survival, conditional survival, and hazard ratio. We obtained fitted survival curves consistent with both the RCT and external evidence, therefore increasing our confidence in the extrapolations and resulting estimated mean survival differences between the arms.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available