Introduction: Globally, resources for health spending, including HIV and tuberculosis (TB), are constrained, and a substantial gap exists between spending and estimated needs. Optima is an allocative efficiency modelling tool that has been used since 2010 in over 50 settings to generate evidence for country-level HIV and TB resource allocation decisions. This evaluation sought to assess the determinants and outcomes of using modelling to inform financing priorities from the perspective of country stakeholders and their international partners. Methods: In October-December 2021, the World Bank and Burnet Institute led 16 small-group virtual interviews with representatives from national governments and international health and funding organizations. Interviewed stakeholders represented nine countries and 11 different disease program country contexts where Optima modelling work had been undertaken. Interview notes were thematically analyzed to evaluate determinants of research translation into policy and practice. Results: Common factors that facilitated or inhibited the application of Optima findings broadly encompassed the perceived validity of findings, health system financing mechanisms, the extent of stakeholder participation, engagement of funding organization, socio-political context, and whether the analysis was timed to suit data and stakeholder needs. Key reported outcomes of Optima analyses related to improved understanding of data and allocative efficiency, support for strategic planning, financial planning, funding advocacy and grant proposals, and influencing investment shifts between interventions or their delivery modalities. Conclusion: Allocative efficiency modeling has supported evidence-informed decision making in numerous contexts and enhanced the conceptual and practical understanding of allocative efficiency. Most immediately, greater involvement of country stakeholders in modelling studies and tying the timing of such studies to key strategic and financial planning decisions may increase the impact on decision making. To further improve relevance and acceptance of modelling findings, there needs to be greater consideration given to integrated disease modelling, equity goals, and financing constraints.

The authors have declared no competing interest.

This work was funded by the World Bank, who contributed to study design, implementation, analysis, interpretation and manuscript review. The authors gratefully acknowledge the contribution to this work of the Victorian Operational Infrastructure Support Program received by the Burnet Institute.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The original QA exercise was not subject to ethics review. The Alfred Hospital Ethics Review Committee approved the collation and analysis of the program QA data (project number:158/22).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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Data from this evaluation is not available for sharing as per ethics agreements. Data and reports for underlying country models are published and openly available in the World Bank Open Knowledge Repository and through Optima.

https://openknowledge.worldbank.org/

http://optimamodel.com/