Abstract
Objectives: To develop methodology for the analysis of individual patient level data from multicentre/multinational randomized controlled trials with the aim of estimating locationspecific parameters to populate decision models for locationspecific decision making.
Methods: Multilevel or hierarchical modelling is the analytical framework used to handle hierarchical costeffectiveness data. Hierarchical modelling was developed in a Bayesian framework and Bayesian shrinkage estimation procedures were used to obtain locationspecific costeffectiveness estimates.
Results: Using data from a recently conducted economic analysis of the RITA 3 trial, locationspecific costeffectiveness measures were obtained and compared to the trialwide results. For the analysed centres, the centrespecific costeffectiveness planes showed higher variability in mean differential cost and mean differential QALY estimates compared to the trial wide results, with the latter having longer left tail estimate distribution. The majority of the locationspecific incremental costeffectiveness ratio results show higher cost per QALY for the intervention strategy compared to the trial wide results (approx. £41,400/QALY). With respect to centrespecific costeffectiveness acceptability curves, the curves for the selected centres display great variability across centres in costeffectiveness for given values of the threshold, λ. If the decision maker is willing to pay £50,000 for an additional QALY, the probability that the intervention strategy is costeffective is, for instance, 0.34 for centre 37, compared to the 0.65 for the trial wide results.
Conclusions: This thesis shows how Bayesian hierarchical modelling can be used to estimate more appropriate clusterspecific parameters for use in decision analytic models where individual patient level data from a multilocation trial are available. Bayesian hierarchical modelling estimates can be used to explore correctly the variability between centres/countries of the costeffectiveness results allowing the correct quantification of uncertainty by adjusting the standard errors to reflect the estimates variability both within and between locations.
Methods: Multilevel or hierarchical modelling is the analytical framework used to handle hierarchical costeffectiveness data. Hierarchical modelling was developed in a Bayesian framework and Bayesian shrinkage estimation procedures were used to obtain locationspecific costeffectiveness estimates.
Results: Using data from a recently conducted economic analysis of the RITA 3 trial, locationspecific costeffectiveness measures were obtained and compared to the trialwide results. For the analysed centres, the centrespecific costeffectiveness planes showed higher variability in mean differential cost and mean differential QALY estimates compared to the trial wide results, with the latter having longer left tail estimate distribution. The majority of the locationspecific incremental costeffectiveness ratio results show higher cost per QALY for the intervention strategy compared to the trial wide results (approx. £41,400/QALY). With respect to centrespecific costeffectiveness acceptability curves, the curves for the selected centres display great variability across centres in costeffectiveness for given values of the threshold, λ. If the decision maker is willing to pay £50,000 for an additional QALY, the probability that the intervention strategy is costeffective is, for instance, 0.34 for centre 37, compared to the 0.65 for the trial wide results.
Conclusions: This thesis shows how Bayesian hierarchical modelling can be used to estimate more appropriate clusterspecific parameters for use in decision analytic models where individual patient level data from a multilocation trial are available. Bayesian hierarchical modelling estimates can be used to explore correctly the variability between centres/countries of the costeffectiveness results allowing the correct quantification of uncertainty by adjusting the standard errors to reflect the estimates variability both within and between locations.
Original language  English 

Qualification  Master of Science 
Awarding Institution 

Award date  1 Oct 2008 
Publication status  Published  2008 