A Special Issue Honoring the Legacy of Adam Wagstaff

This Special Issue of Health Systems & Reform is a collection of articles focused on some of the dominant themes that defined the legacy of one of the most influential international health economists of our time, Adam Wagstaff. The final paper of this issue presents a series of short reflections about different aspects of Adam’s contributions, showing how Adam cast long and supportive shadows in his professional career, which was cut short by his passing in May 2020. His passing triggered a number of us, lucky to have worked and published with him, to put together an issue of original research around topics that Adam cared about and extensively wrote about, namely inequity and health systems. The academic and development communities reacted quickly to Adam’s passing. Reflections about his deep contributions to a range of issues within the health sector came out shortly after his passing. His incredible scholarly impact on his field has already been recognized through plaudits in top health academic journals that have republished some of Adam’s research: Editors’ Selection: the best of Adam Wagstaff in the Journal of Health Economics https://www.sciencedirect.com/journal/journal-ofhealth-economics/special-issue/10MM8GC4TLZ The virtual legacy of Adam Wagstaff in Health Economics https://onlinelibrary.wiley.com/doi/toc/10.1002/ (ISSN)1099-1050.Adam-Wagstaff Less well known about Adam’s career, likely eclipsed by his amazing volume and quality of empirical research, but probably more important than his notable H-index (indicating his work has been frequently cited), was his focus on policy relevance and building a community of practice. Adam’s move from academia, where he had established an impressive career at an early age, to the World Bank, was in large part a yearning to bring evidence to policy. He did so through his own work and research choices as well as by encouraging his research team to link their research to World Bank operations and related policy issues. The second, and longer term, objective, was to recruit, train, encourage, and support young researchers focused on equity in the health sector. This Special Issue of Health Systems & Reform honors Adam’s body of work and achievements by publishing original research on the topic of health systems and equity by researchers who worked with Adam before and since joining the World Bank. We reached out to prominent researchers who wrote papers with Adam, and to his colleagues and mentees at the World Bank, to ascertain interest in submitting papers for consideration. Within days we received an overwhelmingly positive response, including all the papers in this issue.

This Special Issue of Health Systems & Reform is a collection of articles focused on some of the dominant themes that defined the legacy of one of the most influential international health economists of our time, Adam Wagstaff. The final paper of this issue presents a series of short reflections about different aspects of Adam's contributions, showing how Adam cast long and supportive shadows in his professional career, which was cut short by his passing in May 2020. His passing triggered a number of us, lucky to have worked and published with him, to put together an issue of original research around topics that Adam cared about and extensively wrote about, namely inequity and health systems.
The academic and development communities reacted quickly to Adam's passing. Reflections about his deep contributions to a range of issues within the health sector came out shortly after his passing. His incredible scholarly impact on his field has already been recognized through plaudits in top health academic journals that have republished some of Adam's research: Editors Less well known about Adam's career, likely eclipsed by his amazing volume and quality of empirical research, but probably more important than his notable H-index (indicating his work has been frequently cited), was his focus on policy relevance and building a community of practice. Adam's move from academia, where he had established an impressive career at an early age, to the World Bank, was in large part a yearning to bring evidence to policy. He did so through his own work and research choices as well as by encouraging his research team to link their research to World Bank operations and related policy issues. The second, and longer term, objective, was to recruit, train, encourage, and support young researchers focused on equity in the health sector.
This Special Issue of Health Systems & Reform honors Adam's body of work and achievements by publishing original research on the topic of health systems and equity by researchers who worked with Adam before and since joining the World Bank. We reached out to prominent researchers who wrote papers with Adam, and to his colleagues and mentees at the World Bank, to ascertain interest in submitting papers for consideration. Within days we received an overwhelmingly positive response, including all the papers in this issue.

Themes and Organization of This Issue
As the title of the Special Issue suggests, the two main themes are health sector inequalities and empirical health sector research in the service of health system strengthening and reform. The range of papers covered in this issue also reflects some of the topics and objectives covered in Adam's impressive publications record. In staying with the overall focus on this journal, however, we did not cover papers that focused on measurement issues, one of the areas of health economics research that Adam excelled at. The focus is instead on another of Adam's strengths as a health economist, bringing data into policy and decision making and learning from country experiences.
In reaching out to the potential authors, which took place in June and July of 2020, the guest editors explained that we are looking for original research that is reflective of the two main themes, equity and health systems, and that is either empirical or empiricist in nature. In addition to the high quality of the papers, there was a high degree of heterogeneity. Not surprising, a majority of the papers had a country focus, bringing empirical data to identify potential policies or to learn from a country's experience. Other papers took on a broader scope by examining multiple countries or regions, or taking a global perspective. The final order of papers reflects the scaling of data sources and analysis from a subnational to country, regional and global purview. Since the invited authors had either published with Adam, learned from him, or worked with him in various capacities, it is not surprising that each paper used some of Adam's publications as central references or launch points. As we preview the papers in this special issue in the next section, we cite the Wagstaff papers they cited in these articles, and by doing so we create a list of some of Adam's most influential papers.
The last two essays in this issue are not original research. The first is a commentary about Adam and the World Bank penned by the Vice President for Human Development and the Senior Director for Health at the World Bank. The second is a compilation of short reflections on Adam that cover various parts of Adam's career: prior to his joining the World Bank; as a thought leader on equity in health; as a research manager; as the president of the International Health Economics Association; as a producer of countryfocused research; and as a mentor to young economists and researchers.

The Original Research Papers
In the paper titled "Going Granular: Equity of Health Financing at the District and Facility Level in India," Chatterjee and Smith build on methodologies developed and taught by Adam and colleagues at the World Bank, 1-5 with a focus on one state in India. The paper innovates in the use of standard benefit incidence analysis by decentralizing the analysis to the district level (as an administrative function), linking it to budget availability, and needs. The paper exposes weak links at the district level between resources and needs and highlights the pro-rich nature of budget allocation and execution.
The paper by Wang, Chukwuma, Comsa, Dmytraczenko, Gong, and Onofrei, "Generating Political Priority for Primary Health Care Reform in Romania," employs a qualitative approach to examine the passage of reforms intended to address the access, quality and efficiency of primary health care provided as part of social health insurance in Romania. Primary health care services lie at the heart of the universal health coverage, for which Adam helped to develop a measurement approach 6 and monitor as part of global stocktaking of progress on the Sustainable Development Goals. 5 This paper also reminds us of some of Adam's earlier research on social health insurance in Eastern Europe, which also included Romania. 7 Among the authors of this paper are colleagues of Adam's at the World Bank, including some with whom he collaborated on equity analysis in other middle-income countries. 8 In the paper on "Changing Inequalities in Health-Adjusted Life Expectancy by Income and Race in South Africa," Bredenkamp, Burger, Jourdan, and van Doorslaer examine the extent to which South Africa has overcome its legacy of socioeconomic-related inequalities in health outcomes. Their analysis employs research methods pioneered and applied by Adam and colleagues, including the use of the concentration index, quality-adjusted life expectancy and an asset index to measure health-related inequalities. 1,9 The inclusion of this paper in the Special Issue serves to highlight Adam's collaboration between 2016 and 2020 with researchers working in and on South Africa, especially at the University of Stellenbosch 10 where Burger is faculty. Bredenkamp is one of Adam's World Bank colleagues, and worked extensively with him on health equity monitoring at the World Bank. 11,12 Van Doorslaer had a long-standing friendship and collaboration that originated from their time together as students at the University of York in the early 1980s. In a series of more than 25 joint published scientific articles as well as two books, they pioneered much of the work on measuring and analyzing equity in health and health care in health economics, with applications to countries in both the developed and developing world.
The paper by Capuno, Kraft, and O'Donnell, "Filling Potholes on the Road to Universal Health Coverage in the Philippines," examines the extent to which social health insurance provides financial protection to its members and how pro-rich or pro-poor the distribution of PhilHealth benefits are. The theoretical measurement of financial protection, 1 its empirical estimation, 13 and the impact of social health insurance programs 9,14,15 are areas on which Adam worked on extensively in middleincome countries. The authors of this paper previously collaborated with Adam from 2009 to 2013 as members of the Health Equity and Financial Protection Asia (HEFPA) network which Adam co-led, including examining other questions related to PhilHealth insurance coverage, such as how to incentivize enrollment. 16 O'Donnell is a long-time collaborator of Adam's with their first joint publication more than 20 years ago.
In the paper titled "Economic Consequences of Ill-Health in Rural Ethiopia," the authors Debebe, Mebratie, Sparrow, Dekker, Alemu, and Bedi, build on Adam's work on the consequences of ill health in Laos, 17 Vietnam, 18 and China. 19 The context is understanding the causal chain from ill-health to household economic status including poverty traps. Three waves of a household survey (panel) are used to deliver a comprehensive analysis of different channels through which household economic welfare is affected in rural Ethiopia, primarily through impact on labor supply and health expenditure. The paper's findings highlight the value that social safety nets and health financing reforms that promote prepayment schemes may have on the economic welfare of households.
In the paper "Measuring Financial Protection in Health in Brazil: Catastrophic and Poverty Impacts of Health Care Payments Using the Latest National Household Consumption Survey," Araujo and Coelho provide new evidence on financial protection in health in Brazil. Using consumption survey data from 2017/18, they use the methods pioneered by Adam with Eddy van Doorslaer to look at the prevalence of catastrophic and impoverishing health expenditures among Brazilian households. 20 The paper represents a contribution to the steadily growing literature on country trends in and patterns of out-of-pocket health spending. It provides updated estimates for Brazil relative to the existing literature, including Adam's multi-country paper from 2008, 21 and shows how, despite progress toward universal health coverage in Brazil, financial protection remains a salient challenge, in particular for the poor.
The paper by Patenaude, Rao, and Peters, "An Empirical Examination of the Inequality of Forgone Care in India," uses an equity lens to examine a relatively neglected issue concerning those who forgo care for priority maternal and child health services. They apply Adam's methods of standardized concentration indices at national level and various sub-populations 22,23 and in common with Adam's observations in other studies, 24,25 demonstrate how national level findings often mask important variations in inequalities at subnational levels. The authors also used Adam's regressionbased decomposition analyses to identify the drivers of observed inequalities, 26 in this case highlighting how wealth, maternal education, rural location, and state level per capita health spending are associated with the observed inequalities in forgone care.
The paper titled "A Comparative Case Study: Does the Organization of Primary Health Care in Brazil and Turkey Contribute to Reducing Disparities in Access to Care?" by Özçelik, Massuda, Castro, and Barış considers the lessons from Brazil and Turkey's experience with primary health care reform. In both countries, reforms were motivated in large part by inequities in access to health care, which Adam had a hand in documenting. 27 Using a comparative case study approach, the paper connects to the broader literature on the distributional impacts of health system reform, including work by Adam and others to assess progress toward universal health coverage. 28,29 The papers shows that PHC reforms can indeed help address inequities, but that the extent to which that happens depends on complex design and institutional factors.
In the article titled "Making Health Insurance Pro-Poor: Lessons from 20 Developing Countries," Watson, Yazbeck, and Hartel build on previous work by Adam in two ways. The article is a first attempt of knowledge synthesis around health policies to address inequalities in health since the Reaching the Poor Program that was co-directed by Adam with Davidson Gwatkin and Abdo Yazbeck. [30][31][32] The article also links to Adam's publications about health insurance and the extent to which it is or can be equitable and efficient. 15,33,34 The authors find health insurance to be the most popular health financing instrument used in the last 15 years in attempting to address inequality in health, but that the popularity is not matched or justified by the results. More importantly, the authors use the successful examples of health insurance schemes that were pro-poor to identify design elements that can be used in the future to tackle inequality.
In "Identifying Major Health-System Challenges in Developing Countries using PERs: Equity is the Elephant in the Room," Gaudin and Yazbeck develop and use a new data base for health systems analysis from existing analytical studies conducted by the World Bank over a 10-year period. Public Expenditure Reviews are instruments that have been used to address countryspecific needs, but as this article shows, common themes, like issues with inequality and primary health care, appear to be a challenge all over the world regardless of region or level of national income. The article builds on Adam's work 31,32,35 on generating equity-focused data and ensuring that equity concerns and challenges are front and center in global health system performance measurement.
In the paper by Eozenou, Neelsen, and Lindelow on "Trends and Inequalities in Child Health Outcomes," three of Adam's long-time collaborators and fellow World Bank staff come together to examine trends in within-country inequalities in under-five mortality and stunting across the world. Their analysis uses a collection of over 300 household surveys across 102 countries, which Adam, Eozenou and others were instrumental in assembling. 36 Inequalities are measured using the concentration index whose theoretical extensions (such as the achievement index that is used in this paper) 1,3,37 and application to health outcomes (including child mortality 27 and malnutrition 26 ) has been one of the hallmarks of Adam's research.
The authors of "Financial Protection in Health Among the Elderly-A Global Stocktake" (Eozenou, Neelsen, and Smitz) consider themselves both colleagues and mentees of Adam, having worked closely with him over the past 5 years on health equity and financial protection monitoring. Together, they created a large database of household surveys that is used to measure global progress on financial protection goals. 4,38 In this paper, they use that database and build on the previous analyses of financial protection undertaken with Adam 13,39 to examine the specific question of financial protection among elderly households. The idea of analyzing the relationship between aging and financial protection with this database stemmed from the work that Adam led with his colleagues in the context of UHC monitoring, and its completion in time for inclusion in this Special Issue is a tribute to that collaboration and their commitment to continue global analysis of financial protection.
In "Will the Quest for UHC be Derailed?" Sparks, Eozenou, Evans, Kurowski, Kutzin, and Tandon explore the global look at the impact of COVID-19 on the prospects for UHC. The authors, staff of the WHO and the World Bank, who worked with Adam, build on and update some of his earlier work on poverty and inequality, 12,24 on social health insurance, 14,15 and on tracking UHC. 5,40,41 The paper explores the various channels that the economic shock due to the pandemic will impact UHC, and identifies mechanisms that countries can implement to prioritize the poor and marginalized for ensuring improved access to care.