Out of Date or Best Before? A Commentary on the Relevance of Economic Evaluations Over Time

Abstract

The impact of time on the applicability and relevance of historical economic evaluations can be considerable. Ignoring this may lead to the use of weak or invalid evidence to inform important research questions or resource allocation decisions, as historical economic evaluations may have reached different conclusions compared to if a similar study been conducted more recently. There are multiple factors that contribute towards evidence becoming outdated including changes to the relevant decision problem (e.g., comparators), changes to parameters (such as costs, utilities, and resource use) and methodological updates (e.g., recommendations on uncertainty analysis). Researchers reviewing economic evaluations need to consider whether changes over time would influence the study design and results if the evaluation were repeated, to the extent that it is no longer helpful or informative. In this paper we summarise these key issues and make recommendations about how and whether researchers can future-proof their economic evaluations. Key points Economic evaluations invariably become less relevant to the present day over time, as data availability, preferred methods, clinical pathways, and costs continue to change.  In this commentary we reflect on the range of issues which affect the timeliness of an economic evaluation and reflect on steps that individuals conducting economic evaluations could take to improve the future relevance of their studies.  The shelf-life of an economic evaluation is highly dependent on a range of factors and will differ greatly across contexts (such as by disease areas and intervention type), reviewers and decisionmakers need to carefully consider this when evaluating economic evaluation evidence.

Economic evaluation of a water fluoridation scheme in Cumbria, UK

“…Fifth, while costs and outcome data are presented at 2014 values, it is recognized that parameters within cost‐effectiveness studies go out of date so decision‐makers need to be aware that if a study was repeated today there may be differences in costs and health outcomes 38 …”

“…Fifth, while costs and outcome data are presented at 2014 values, it is recognized that parameters within cost-effectiveness studies go out of date so decision-makers need to be aware that if a study was repeated today there may be differences in costs and health outcomes. 38 Sixth, the current work only considers the benefits of water fluoridation and has not considered the only broadly accepted risk of water fluoridation, fluorosis. This is due to the birth cohort examinations concluding at 5 years of age, whereas fluorosis examinations are typically conduction around 12 years of age when the anterior permanent teeth are erupted.…”

Living Health Technology Assessment: Issues, Challenges and Opportunities

“…The model structural assumptions and the model inputs can become out-of-date over time, as well as the methods used to estimate the cost effectiveness [ 10 ]. Examples of changes related to the model structure include a new technology becoming standard of care, or additional knowledge around the clinical condition that would influence either the model health states or structural assumptions.…”