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This section is currently being updated

ETA end of March 2024!

Research

Summary

My research analyses healthcare systems and disparities in access to care through the lens of organ failure, donation, and transplantation, with a focus on solid organs and cardiovascular disease in the US.

I use quantitative research methods to answer three research questions: 1) why do people reach organ failure, therefore necessitating organ transplants?; 2) can patients who need organs access them?; 3) how do the determining factors of access to care relate to outcomes? Across the three questions, I try to understand what health systems can do to improve care for these populations.

Featured Research

Machado SR, Vargas-Lopes F (2023) “Medicaid Expansion and the Mechanics of Increased Access to Organ Transplantation” with Francisca Vargas Lopes (Erasmus U) - in preparation for submission to American Journal of Health Economics

Using the universe of US-based organ transplant candidates and recipients, we measure the causal effect of Medicaid expansion on transplantation. We quantify the impact on a range of outcomes that relate to how expanding Medicaid coverage affects access to care and other payers, in a setting where patient ex ante and ex post moral hazard are minimized.

 

Current draft available here

Publications

Barros, PP, Machado, SR, (2010) “Money for Nothing: The Net Costs of Medical Training”, Health Care Management Science, 13(3): 234-255. https://doi.org/10.1007/s10729-010-9126-7 (available here)

 

DeFillipis, EM, Vaduganathan, M, Machado, SR, Stehlik, J, Mehra, MR (2018) “Emerging Trends in Financing of Adult Heart Transplantation in the United States”, JACC: Heart Failure. Dec 2018, 969; DOI: 10.1016/j.jchf.2018.10.001

Media Coverage: Cardiovascular Business

 

Vaduganathan, M, Machado, SR, DeFilippis, EM, Bajaj, N, Stehlik, J, Mossialos, E, Jarcho, JA, Mehra, MR (2019) “Organ Donation and Drug Intoxication-Related Deaths in the United States”, New England Journal of Medicine. Feb 2019, 380(6): 597-599; DOI: 10.1056/NEJMc1810758. [co-first author]      

Selected Media Coverage:  Drugs.com, MedicalXPress, Medscape, Medscape Podcast, US News

 

Machado, SR, Vaduganathan, M,  Mehra, MR (2019) “Adoption of hepatitis C virus–infected donor hearts: A “middle child” no more.” The Journal of Heart and Lung Transplantation, 38(9), 918-919. DOI: 10.1016/j.healun.2019.07.005

 

Buckley LF, Vaduganathan M, Lauffenburger JC, Machado SR, Fanikos J. (2020)  “Unintended Impact of US Food and Drug Administration Recalls on the Use of Contaminated and Non-Contaminated Angiotensin Receptor Blockers Among Medicaid Beneficiaries.” Ann Pharmacother. 2020;54(6):615-616. https://doi.org/10.1177/1060028019897388

 

Aslam S, Grossi P, Schlendorf KH, et al. (2020) “Utilization of hepatitis C virus–infected organ donors in cardiothoracic transplantation: An ISHLT expert consensus statement.” The Journal of Heart and Lung Transplantation. 2020;39(5):418-432.2020 [working group member]  https://doi.org/10.1016/j.healun.2020.03.004

 

Vasey B, Shankar AH, Herrera BB, Becerra A, Xhaja K, Echenagucia M, Machado, SR et al. (2020) “Multivariate time-series analysis of biomarkers from a dengue cohort offers new approaches for diagnosis and prognosis.” PLoS Negl Trop Dis 14(6): e0008199. https://doi.org/10.1371/journal.pntd.0008199

 

Sumarsono A, Buckley LF, Machado SR, Vaduganathan M, et al. (2020) “Medicaid Expansion and Utilization of Antihyperglycemic Therapies”. Diabetes Care. doi:10.2337/dc20-0735

 

Sinnenberg L, Machado SR, Ostrominski JW, Stehlik J, Mehra MR, Vaduganathan M. (2020) “Citizenship Status and Cardiothoracic Organ Transplantation in the United States”. Circulation: Heart Failure. 0(0)doi:10.1161/CIRCHEARTFAILURE.120.007788 [Co-first author]

 

Machado, SR, Jayawardana, S, Mossialos, E, Vaduganathan, M (2021). “Physician density by specialty type in urban and rural counties in the US, 2010 to 2017”, JAMA network open, 4(1), e2033994-e2033994. doi:10.1001/jamanetworkopen.2020.33994 [First author]

 

Costa-Font, J, Machado, SR (2021). “How Can Policy Interventions Encourage Pro-Social Behaviours in the Health System?”, LSE Public Policy Review. 2021; 1(3): 6, pp. 1–10. https://doi.org/10.31389/lseppr.17  

Machado SR, Sumarsono A, Vaduganathan M. (2021) “Midlife Wealth Mobility and Long-term Cardiovascular Health”. JAMA Cardiology. Published online June 30, 2021. doi:10.1001/jamacardio.2021.2056 [First author]

Selected media coverage: Yahoo!news, tctMD, Eat this not that, FAZ, The Straits Times

Preprint, submitted, and in preparation

Machado SR, Vargas-Lopes F (2023) “Medicaid Expansion and the Mechanics of Increased Access to Organ Transplantation” with Francisca Vargas Lopes (Erasmus U) - in preparation for submission to American Journal of Health Economics

Using the universe of US-based organ transplant candidates and recipients, we measure the causal effect of Medicaid expansion on transplantation. We quantify the impact on a range of outcomes that relate to how expanding Medicaid coverage affects access to care and other payers, in a setting where patient ex ante and ex post moral hazard are minimized.

 

Current draft available here

 

Santos C, Costa E, Machado SR (2021) “Uncovering Competitive Forces in Prescription Drug Markets - Evidence from Statins”, with Carolina Santos (Nova SBE) and Eduardo Costa (Nova SBE) – in preparation for  submission to Journal of Health Economics

We analyse the relationship between price caps and pharmaceutical companies' market power. We define distance to price cap as companies' strategic variable. We then use fixed effects models to estimate the relationship between this variable, multimarket interaction, and ownership structure. We further investigate the effect of generic entry in a separate but related market, using synthetic control methods.

 

Costa-Font J, Salyga H, Machado SR (2021) "Pro-Social Behavioural Spillovers and Altruism Budgets Across Domains", submitted to Oxford Economics Papers

We use a unique longitudinal survey on prosocial behavior, from the Netherlands, to measure spillovers of tax incentives for cultural philanthropy and of humanitarian aid campaigns on health-related prosocial behavior (monetary and blood donations). Our findings highlight the importance of trade-offs in prosocial behaviors across domains.

Machado SR (2020) “Estimating the Blood Supply Elasticity: Evidence from a Universal Benefit Scheme” - in preparation for submission to Review of Economics and Statistics

I estimate the blood supply semi-elasticity to a change in quasi-monetary incentives for blood donors. I use the Chaisemartin and D'Haultefoeuille differences-in-differences estimator to quantify unconditional and conditional elasticity of blood supply. Since the demand for blood is endogenous, I instrument for the number of blood drives using variation in the number of weekend days per month and a county's propensity to host blood drives on weekends. I find large elasticities of supply, particularly in face of benefit decreases.

Gilbert O, Lefebvre C, Hanchate A, Machado SR, Mahler S (2021) “Cost Effectiveness of Chest Pain Triage with the HEART Pathway” – submitted to American Heart Journal

 

Machado SR, Perez BP, Papanicolas IN (2021) “Crowdfunding for transplants: the role of race and ethnicity” [First author] – in preparation for submission to Health Affairs

Perez BP, Machado SR, Andrews JT, Kourtellis N, (2020) “I call BS: Fraud Detection in Crowdfunding Campaigns” arXiv:2006.16849v1 - submitted to WSDM’22

Manuscripts and preprints available upon reasonable request.

Coming up next

“Crowdsource funding and organ transplantation in the United States”, with Beatrice Perez, Muthiah Vaduganathan, and Mandeep R. Mehra [First author]

"Association between kidney allocation policy and payer-specific provider decision-making"

"Effect of donation time on blood donor retention: a population-wide retrospective study"

 

“Firearm Injury Associated Deaths and Organ Transplantation” with Ersilia M. DeFilippis, Muthiah Vaduganathan, Elias Mossialos, and Mandeep R. Mehra [First author] 

“Contemporary Racial/Ethnic Differences in Deceased Donation in the United States”, with John W. Ostrominski, Muthiah Vaduganathan, Elias Mossialos, and Mandeep R. Mehra [First author] 

 

“Marketplace Plan Designs for Cardiometabolic Therapies in Rural and Urban Counties in the US”, with Zachary Hermes, David A Bunn, Duaa AbdelHameid, Zainab Jaji, and  Muthiah Vaduganathan  [Senior author] 

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