OBJECTIVES: HTA bodies are increasingly considering environmental impacts (EIs) in decision making to promote greater sustainability in healthcare. Methods such as information conduit, parallel evaluations and multicriteria decision analysis have been proposed, in addition to integrated assessments, where clinical, economic and environmental data are synthesized in a single quantitative analysis. This research assessed published methods for integrated assessments and the extent to which EIs could influence HTA decision making.

METHODS: Targeted searches in PudMed, Google Scholar and the ISPOR Presentations Database were conducted to identify published methods for integrated assessments of health technologies. Details extracted included outcomes used to quantify EIs and integration method. Where publications reported case studies, the impact of integrating EI was examined.

RESULTS: Of the 14 included studies, eight reported case studies and six proposed methods for integrating EI into economic evaluations. The most commonly reported outcome used to quantify EIs was carbon dioxide equivalent (CO₂e) emissions, particularly in studies examining the EIs of asthma inhalers. One study employed novel decision-making metrics (incremental carbon footprint effectiveness/cost ratios), four studies costed CO₂e emissions for subsequent use in economic evaluation, and two studies integrated EIs into incremental cost-effectiveness ratios (ICERs). The studies which costed CO₂e emissions indicated that carbon costs constitute a higher proportion of the total cost of inhalers (0.03–84.7%) versus non-inhalers (0.0–2.1%). Across the case studies reporting ICERs, integration of EIs resulted in a 0.2–15.7% change in magnitude of the ICER.

CONCLUSIONS: Evidence regarding the integration of EIs into economic evaluations is limited, but for technologies with a high carbon footprint, such as asthma inhalers, integrating EIs could be highly influential for decision making. The proportion of the total cost that CO₂e emissions constituted varied greatly depending on the technology and costing method(s) used. Therefore, further guidance on methodology to incorporate EIs into economic evaluation is warranted.