The potential application of cost consequence analysis to public health interventions to increase accessibility of health economic evidence to decision makers

Trueman, Paul (2020) The potential application of cost consequence analysis to public health interventions to increase accessibility of health economic evidence to decision makers. Doctoral thesis (PhD by Published Works), Manchester Metropolitan University.

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Abstract

This thesis explores the application of economic evaluation to public health interventions. The motivation for the thesis was experience gained through a number of applied research programmes on which the author was the lead investigator or co-lead investigator. The experience gained over the course of these programmes highlighted that cost utility analysis has significant shortcomings when applied to public health interventions. Many of these shortcomings stem from fundamental uncertainties around the attributable effect of the public health interventions which is more difficult to estimate in tightly controlled studies than other healthcare interventions, such as pharmaceuticals. In addition, where data are available they typically report easilymeasured,short-term, behaviour change such as an increase in physical activity, rather than the resulting longterm health outcome, such as a reduction in cardiovascular disease. By adopting long-term (even lifetime) time horizons in economic models, health economists are often required to make heroic assumptions about the longevity and reproducibility of the short-term effects observed in studies and their relationship with health outcomes. There are also concerns with cost utility analysis that go beyond the data inputs to the core principles of the philosophical approach that underlies this method. The foundation of cost utility analysis is extra-welfarism, which assumes that population health is the maximand in policy decisions and that presenting outcomes in a cost per quality adjusted life year (QALY) format is accessible to all relevant decision makers. In many cases, public health interventions have impacts beyond health outcomes and the decision makers for determining whether an intervention should be made available may include non-healthcare stakeholders. Environmental interventions to promote physical activity included in this thesis are a good example of this. Investment to support this intervention is unlikely to be sourced entirely from healthcare budgets, so it is important that evalutions of such programmes adopt an appropriate perspective and report outcomes in an accessible format for all decision makers. A final concern about the application of cost utility analysis is the requirement to aggregate costs and outcomes into a composite ratio, typically the incremental cost per QALY. Whilst this provides a common denominator for decision making purposes allowing interventions to be directly compared, the use of a ratio can mask the magnitude of absolute changes in outcomes. Rather than rely on a composite ratio, decision makers would be advised to consider the absolute changes in outcomes, whether these are clinically meaningful and the degree of uncertainty around them. The over-arching objective of this thesis is to critically assess the commonly applied methods of economic evaluation to public health interventions, with a particular focus on cost utility analysis. Rather than undertake a methodological critique, the thesis considers a series of applied economic evaluations conducted by the author, the lessons learned throughout these and the methodological preferences that resulted. These applied 6 studies provided the impetus to explore alternative approaches to economic evaluation, including the application of cost benefit analysis in the evaluation of environmental interventions to promote physical activity and interventions to promote breastfeeding. However, like cost utility analysis, the outcomes of cost benefit analyses aggregate costs and outcomes into a composite ratio (the cost benefit ratio) which may continue to mask uncertainty around the absolute changes in outcomes. By necessity, cost benefit analysis also excludes any outcomes which can’t be quantified in monetary terms. In light of this, cost consequence analysis was applied to subsequent economic evaluations as a means of addressing some of the shortcomings presented above. By presenting outcomes in a disaggregated format, decision makers from multiple sectors can determine how they would benefit from an intervention and the degree to which they may want to contribute to funding. Reporting outcomes in this way also eliminates the need to utilise a narrow health perspective, as in cost utility analysis, or to quantify all outcomes in monetary units as in cost benefit analysis. On the basis of the applied research presented in this thesis, the author suggests that cost consequence analysis should be the preferred method of economic evaluation for public health interventions, particularly those that have inter-sectoral costs and effects. The thesis concludes with some reflections on alternative methods of economic evaluation and the final chapter includes a simple framework to guide the choice of economic evaluation methods. These are intended to inform future evaluatuions of public health interventions to ensure that they adopt pragmatic methods and present outcomes in an accessible format for decision makers. By doing so, researchers can increase the influence of health economics on public health service provision and contribute to more efficient use of scarce resources.