Exploring the Generalizability of Foreign Cost-Effectiveness Analysis to Spain Using Data From a Scoping Review of Multinational Studies.

Objective: This study examines the generalizability of foreign economic evaluations to the Spanish healthcare system. The research aims to describe the cross-country adaptation methods identified in a scoping review of multinational cost-utility analyses and to examine the probability of concordant funding decisions between Spanish and foreign results, as well as to identify factors influencing generalizability.

Methods: First, a scoping review of multinational studies reporting cost-utility analyses for at least two countries, including Spain, was conducted using MEDLINE, PubMed, Embase and Web of Science in April 2025. Data related to transferability were extracted and a narrative synthesis was performed. Second, a dataset of case comparisons-each defined as a technology against a comparator in a specific population-was developed from the identified studies. Each foreign comparison was matched to its Spanish equivalent within the same study. Incremental cost-effectiveness ratios (ICERs) were converted to 2024 Spanish Euros and compared against a threshold of €30,000 per quality-adjusted life year (QALY). A multilevel logit model was used, with a binary variable indicating decision concordance between Spanish and foreign ICERs/dominance as the dependent variable. We also analysed the distances in the incremental costs and incremental QALYs between countries using a log-normal bivariate model. Country-specific and other study-related factors were considered as independent variables in both models.

Results: The review included 57 studies. Most were funded by drug manufacturers and conducted in Europe. The majority of authors did not specify their reasons for selecting countries. All but three studies attempted to use local costs, probabilities and/or epidemiological data. Twelve studies incorporated country-specific utilities. A total of 644 comparisons were analysed; 142 were Spanish results and 502 were foreign results with their Spanish equivalents. The cost-effectiveness plane quadrant of the foreign result matched the Spanish result in 84% of cases. Assuming a threshold of €30,000 per QALY, the funding decisions were the same in 93% of cases. The probability of decision concordance was higher when the study was conducted in a Eurozone country or in the United Kingdom. Sensitivity analysis showed the variability of decisions depending on the selected cost-effectiveness threshold. Similar variables were found as relevant factors explaining the distance in the incremental QALYs analysis.

Conclusion: Foreign cost-effectiveness results of those studies analysing drugs from Eurozone countries such as France, Germany, Italy, or from the United Kingdom can often be generalizable and provide meaningful insights for decision making in Spain. However, these findings should not be used as a reason to avoid country-specific studies if they are feasible. Further research is needed to determine if these findings apply to other health technologies. Limitations of the study include the lack of a formal assessment of the methodological quality of the selected studies and the potential risks of bias.