Clinical implications of assumptions in cost-effectiveness analyses of systemic therapies for metastatic colorectal cancer.

Abstract

e16021 Background: Considerable variation is observed in model-based cost-effectiveness analyses of systemic therapies for metastatic colorectal cancer (mCRC). This review provides a comprehensive and detailed discussion of structural and methodological assumptions in such analyses, and how those might impact health and economic outcomes. Methods: Five databases (EMBASE, MEDLINE, Cochrane Library, Health Technology Assessment, and National Health Service Health Economic Evaluation Database) were searched for model-based health economic evaluations of systemic mCRC treatment. Study selection, appraisal using the Consolidated Health Economic Evaluation Reporting Standards checklist, and data extraction was performed by two reviewers independently. Data extraction included general study characteristics, economic methods and assumptions, model structures and modelling technique, evidence used, extrapolation methods, validation efforts, and analyses performed. Economic outcomes were indexed to 2019 US$. Results: The search yielded 1,418 publications of which 54 were included, representing 51 unique studies. Most studies focused on first-line treatment (n = 29, 57%), followed by third-line treatment (n = 13, 25%). Although most studies mentioned consideration of further treatments (n = 29, 57%), this was typically only done by means of a lumpsum treatment cost (n = 21). Studies used varied modelling techniques and model structures, and different control strategies were adopted by studies aiming to estimate the cost-effectiveness of the same treatment. Only 15 studies (29%) reported some sort of model validation. Health economic outcomes for specific strategies differed substantially between studies. For example, survival following first-line treatment with fluorouracil, leucovorin, and oxaliplatin ranged from 1.21 to 7.33 years, with treatment costs ranging from US$8,125 to US$126,606. Conclusions: Model-based cost-effectiveness analyses of systemic mCRC treatments have adopted varied modelling methods and structures, which has resulted in substantial different health economic outcome estimates between studies, for example in terms of overall survival and average treatment cost per patient. Models generally focus on first-line treatment without considering the use of downstream treatments, suggesting these studies likely present biased results. This may impact the uptake of new systemic therapies.