Using mathematical modelling to make a difference

Shocking difference

He says, “The shocking difference in access to healthcare between rich and poor countries is widely known, and great attention is paid to the issues in funding and developing effective medicines, but it seems that far less attention is paid to one of the key contributing factors to the situation: the design and management of health systems.

“I realised then that the academic community interested in health systems in low-income countries was mostly composed of public-health experts, health economists, epidemiologists and clinical researchers, even though many of the key challenges I was seeing on the ground were clearly related to operations and supply-chain management. That was my motivation to work on health-delivery systems in low-income countries.”

Begun in 2010 and supported by a partnership that ultimately included the Zambian Ministry of Health, the World Bank, the UK Government’s Department for International Development, UNICEF/UNDP and computer giant IBM, his research into the impact of inventory management on stockouts of essential drugs in Sub-Saharan Africa, known as the eZICS (Enhanced Zambia Inventory Control System) project, improved access to essential medicines for under-privileged populations in Zambia through a hi-tech inventory distribution system. The first such system to be deployed in the public sector in sub-Saharan Africa, eZICS drew wide acclaim from policymakers and operators in the field alike. Dr Bonface Fundafunda, then Managing Director of the Zambian government agency managing the project, said it had enabled the country “to start seeing assured healthcare service provision”, and had contributed greatly to “positive health outcomes for Zambia”. The model may also be adopted by other countries with similar problems in accessing essential medicines, while the initiative continues to create impact in Zambia through the Wheeler Institute (see panel). 

It was not the last of Professor Gallien’s studies to use mathematical modelling techniques to help solve global health challenges. Another groundbreaking piece of research, ‘Improving HIV early infant diagnosis supply chains in sub-Saharan Africa: Models and application to Mozambique operations research’, used the lessons of operations management to improve population health by identifying opportunities in the structure of the supply chain itself.

With Jonas Oddur Jonasson, Associate Professor at the MIT Sloan School of Management (then a student of the LBS PhD programme in Management Science and Operations) and Sarang Deo from the Indian School of Business, Professor Gallien developed a modeling framework to generate operational improvements in the assignment of clinics to laboratories and the allocation of capacity across laboratories to improve EID significantly. A seminal piece of research (it was the first to look at improving supply chains in HIV EID), it won a number of prestigious awards, including making the Financial Times list of top 100 business school papers with positive societal impact.

Optimising the use of funds

The fact that Professor Gallien spends as much time in the field as in the classroom is down to the insights stemming from his interest in the intersection of theory and practice. This also explains why he is profoundly concerned with how resources are used in improving global healthcare. 

That was the motivation to study the relationship between the Global Fund to Fight AIDS, Tuberculosis and Malaria and its grant recipients. In a 2016 paper, Professor Gallien and his coauthors built a model to predict the joint impact of procurement and grant disbursement processes on drug availability for the fund’s recipient countries in Africa. 

Its findings showed that interventions to shift some fund disbursements upfront could protect against disbursement-timing uncertainty and thus prove more effective (and cost-efficient) than other interventions. 

Equally significantly, the research showed that the use of larger upfront disbursements (known as cash buffers) was the most effective intervention – a key insight given that the Global Fund invests US$4 billion a year to strengthen health systems in more than 100 countries.

The desire to have real-world impact continues to inform Professor Gallien’s research choices. The project he is currently “most excited about” is a study on the design of maternity waiting-homes networks. He says, “One of the big challenges here is that many pregnant women who live in remote areas deliver babies without any medical assistance. An alternative is to provide them with the option to travel to a facility where they can stay for a number of days before their due date and safely deliver their baby, instead of risking delivering then in dangerous or unsanitary situations when their labour starts. I’m developing mathematical models and analysing data in order to develop rigorous, data-driven recommendations to design such a system.”

Leveraging technology 

Another area of particular interest, and the subject of a forthcoming paper, is how Community Health Workers (CHWs) can be deployed to optimal effect in sub-Saharan Africa. Increasingly important in ensuring access to healthcare for under-served populations in many countries, CHW programmes are being rapidly scaled up and integrated into national healthcare-delivery systems. The key policy question is how best to deploy CHWs to different regions, given differences in disease burden, population density and limited resources. Based on CHW data from Ghana and existing disease-progression models, Professor Gallien’s research demonstrates that current practice, which uses a rule-of-thumb ratio of 500 patients per CHW, is not optimal. In fact, an optimal deployment strategy would adjust the ratio based on both epidemiological factors and operational ones, with the optimal patients-to-CHW ratio varying from 368 (low patient density) to 823 (high patient density) in areas of low disease burden, and from 227 to 399 in areas of high disease burden.

Meta motivation

Besides its utility in the field, Professor Gallien reveals a ‘meta’ motivation behind the project. “After I completed my degree, I didn’t want to be a pure mathematician, because I missed connecting with the real world and having a practical impact. I’ve always been interested in real-world problems that require analytical skills or mathematical modelling to be resolved.”

There were also more directly personal reasons for the path he chose: “My social and family circles included many physicians, and all three countries I’ve lived in have benefited from colonisation and slavery at some point in history. Working on health-delivery systems in low-income countries is one way, however humble, to do something about the problems of that legacy.”