Equity in Disease Transmission Modelling

Written by Gabriela Gomez and Graham Medley

September 12, 2018

The overarching principle of the Sustainable Development Goals is to leave no one behind. This applies especially to health– a fundamental right underpinning this agenda for change. Maximising health benefits and value for money remains a priority in resource allocations. However, countries and funders consider equity a priority  as well. To inform and facilitate these decisions, economists have recently developed methods for equity-informative economic evaluations. However, applying these methods to infectious disease control presents different conceptual and methodological challenges. These issues mainly relate to the dynamic nature of disease transmission models used for priority settings in global health.

Disease Transmission Models

By definition, disease transmission models are based on heterogeneities (of risk and disease) within populations. Since populations differ in multiple ways transmission models create subgroups. These subgroups are defined by behaviours and/or other determinants of risk. We then model transmission between groups. The transmission outcomes subsequently provide us with a framework to explore the role of heterogeneity in the distribution of health, healthcare utilisation, and healthcare financing. These form the basis of equity considerations. 

Equity, economic evaluation, and disease transmission modelling

At the end of March 2018, we held a workshop on ‘Equity, economic evaluation, and disease transmission modelling’. We organised the workshop under the umbrella of the International Decision Support Initiative, a global initiative to support decision makers in priority-setting for universal health coverage. It was supported by the Bill & Melinda Gates Foundation, the UK Department for International Development, and the Rockefeller Foundation. And it was co-convened by the TB Modelling and Analysis Consortium and the Centre for the Mathematical Modelling of Infectious Diseases at the London School of Hygiene and Tropical Medicine.

The workshop linked the economic, modelling, and policy communities to encourage the exchange of methods. We were also concerned to identify opportunities and challenges that researchers and professionals face when using disease transmission modelling to evaluate the equity of global health interventions. 

During the workshop meeting, we reviewed the theoretical foundations of equity. We also considered the variety of approaches for incorporating them in economic evaluations. Furthermore, we provided an overview of heterogeneity approaches in disease transmission modelling and examined the added value of disease transmission models for equity analyses. In addition, we outlined the methodological challenges to, and opportunities for the inclusion of equity considerations in disease transmission model-based economic evaluations.

Key outcomes

Key conclusions from this workshop included a call for promotion of transparency in the reporting of processes. This will help to identify and engage appropriate decision makers. Outcomes also involved the definition of policy-relevant equity questions and the choice of equity frame; methods; implicit assumptions; and uncertainty. We pointed out major concerns regarding data gaps in the correlation between equity, risk dimensions and social mixing.

Further details about key discussion points and main outcomes of the meeting will be published shortly in a forthcoming report. The report will be available on the website of the International Decision Support Initiative. We furthermore expect to issue a joint statement from meeting participants to inform data and methods specifications related to the Reference Case for Economic Evaluation in Global Health by the end of 2018. The strengthening of methods will benefit the progress towards the Sustainable Development Goals and universal health coverage targets.

About the author

Gabriela Gomez is an Associate Professor of Economics of Infectious Diseases and a member of the Centre for Health Economics in London. Graham Medley is a Professor of Infectious Disease Modelling and the Director of the Centre for the Mathematical Modelling of Infectious Diseases. Both work in the Department for Global Health and Development at the London School of Hygiene and Tropical Medicine.