Do the Health Effects of a Social Pension Endure? Evidence Eight Years After Program Introduction in Vietnam (Lead author) - Under review by Economics and Human Biology

Non-contributory social pensions have expanded across low- and middle-income countries, yet little is known about whether their health benefits persist as programs mature and benefit values erode. This study examines Vietnam’s 2011 social pension reform, which lowered eligibility from age 85 to 80, eight years after implementation. Using the 2019 Survey on Older Persons and Social Health Insurance and a fuzzy regression discontinuity design at the age-80 threshold, we assess effects on a composite health index, depressive symptoms, and life satisfaction, and compare findings with earlier evidence from the 2011 Vietnam National Survey on Aging. Unlike the positive effects documented at program launch, 2019 instrumental-variable estimates are small and statistically insignificant across outcomes. Mechanism analyses suggest that cumulative inflation reduced the transfer’s real value, weakening financial security despite higher nominal income. These findings highlight the importance of benefit adequacy and cost-of-living indexation for sustaining health gains from social pensions.

Environmental Risks and Early Childhood Development: Evidence from Drinking Water contamination (Lead author) - Under review by World Development

We examine the causal effect of microbial drinking water contamination on early childhood development (ECD) using nationally representative data from 23 LMICs collected through the sixth round of the UNICEF Multiple Indicator Cluster Surveys. The 2SLS estimates indicate that exposure to contaminated drinking water reduces the probability of being developmentally on track by 4.5 percentage points (6.6%). The results are robust to a battery of robustness checks. The adverse effects are larger among children in rural areas, girls, and, to a lesser extent, older preschool-aged children. Mechanism analyses suggest that contaminated drinking water increases diarrhea and underweight, both of which are negatively associated with ECD. The findings identify microbiological water safety as an important environmental determinant of early human capital formation and suggest that investments in safe drinking water may generate developmental returns.

Geographic Accessibility to Healthcare and Child Undernutrition Across 24 Low- and Middle-Income Countries (Lead author) - Under review by International Journal  for Equity in Health

Geographic access to healthcare facilities is a key spatial determinant of child health in LMICs, yet large-scale, cross-national evidence linking travel time to child nutritional outcomes remains limited. Linking geo-referenced DHS data for 240,368 children under five in 24 LMICs with motorized travel-time estimates derived from global friction surfaces, we find that a one-standard-deviation increase in travel time, equivalent to approximately 16 additional minutes of travel beyond the sample average (24.5 minutes), is associated with a 2.73 pps (9.9%) increase in the probability of stunting and a 3.38 pps (17.2%) increase in the probability of underweight. Mechanism analyses suggest that geographic barriers operate through reduced antenatal care attendance, lower institutional delivery, incomplete vaccination, limited infant and young child feeding counselling, and higher maternal amenia. Policy simulations indicate that ensuring access to a health facility within 30 minutes would be associated with modest reductions in malnutrition prevalence overall, but substantially larger predicted gains among rural and low-income populations where geographic barriers remain most pronounced.

Income-Related Inequalities in the top Common Chronic Diseases Among Vietnamese Older People (Lead author with Prof. Long Giang, Dr. Thu Bui, Van Truong, and Anh To) - Under review by Ageing & Society

While multi-morbidity prevalence among older adults is high, research has primarily focused on its socioeconomic determinants, neglecting socioeconomic-related inequalities in the most common chronic diseases. This study aimed to address this gap by examining income-related inequalities in the top three chronic diseases (arthritis, blood pressure, and heart disease) among Vietnamese older adults. We used data from the 2019 Vietnam National Aging Survey (N=2,200) with concentration index (CI) and regression-based decomposition techniques. The prevalence of experiencing all three diseases was significantly higher among low-income individuals (CI=-0.069, p<0.05). Decomposition analysis revealed that income, self-rated health, and financial transfers from children were the main drivers of the observed inequality, contributing approximately 27.6%, 16.7%, and 14%, respectively. Findings of this study provides valuable evidence for policymakers aiming to address health inequalities in chronic diseases among older adults since such inequalities can lead to long-term challenges in accessing healthcare and potentially contribute to rising healthcare costs.

The effects of public health insurance on healthcare expenditures among older beneficiaries in Vietnam: RD-DID approach (Lead author with Prof. Rei Goto and Prof. Yoko Ibuka)

This paper evaluates the effects of changes in health insurance co-payment rates stipulated in the 2009 Health Insurance Law on healthcare expenditures and utilization by older pensioners in Vietnam. We adopt the most current appropriate econometric techniques in health economics to model healthcare data and then we exploit the enactment of the 2009 Law as a natural experiment to conduct a quasi-experiment study using RD-DID estimations. Using data from the Vietnam Household Living Standard Survey 2004-2014, we found that the effects of the 2009 Law, based on the best-fitting models for healthcare expenditure and utilization outcomes, were a significant increase in healthcare spending for both outpatient and the total healthcare expenditures, while the number of outpatient and inpatient visits were found to be significantly increased across levels of healthcare facilities. The results of this study suggest the ex-ante moral hazard in the use of healthcare whereby individuals who are offered a lower rate of co-payment tend to use more care.