Conceptual Modelling For Health Economic Model Development

P Tappenden

Introduction

Health economic evaluation is a general framework for informing decisions about whether particular health technologies represent a cost-effective use of health care resources. Commonly, the evidence required to inform a decision about the cost-effectiveness of a given set of competing health technologies is not available from a single source. The use of mathematical modelling can be used to support this decision-analytic framework thereby allowing the full range of relevant evidence to be synthesised and brought to bear on the decision problem.1 The process of developing a decision- analytic model is generally seen as being iterative, and requires the model developer to make a substantial number of choices about what should be included in a model and how these included phenomena should be related to one another. These choices take place at every stage of the model development process, and include choices about the comparators to be assessed, choices about which health states and sequences of events will comprise the model’s structure, choices about which evidence sources should be used to inform the model parameters, and choices about statistical methods for deriving the model’s parameters, to name but a few. Importantly the absence of perfect information through which to comprehensively validate a model means that there is rarely a definitive means through which to prospectively determine whether these choices are right or wrong. Instead, model development choices are made on the basis of subjective judgements, with the ultimate goal of developing a model which will be useful in informing the decision at hand.