Thesis Title: Disease prevention, control, and treatment
Thesis Committee:
Dr. Pinar Keskinocak (advisor), ISyE, Georgia Institute of Technology
Dr. Joel Sokol (advisor), ISyE, Georgia Institute of Technology
Dr. Lauren N. Steimle, ISyE, Georgia Institute of Technology
Dr. L. Beril Toktay, Scheller College of Business, Georgia Institute of Technology
Dr. Yao-Hsuan Chen, Health Economic and Decision Sciences, MSD (UK) Limited
Date and Time: Tue 5/30/2023, 12:30 PM - 2:00 PM ET
Abstract:
This thesis focuses on the applications of operations research in disease prevention, control, and treatment. In particular, it encompasses the following four topics: i) vaccine pricing across a group of countries considering equity (in particular, ability and willingness to pay); ii) personalized childhood immunization schedule recommendations; iii) the impact of diagnostic testing capacity and compliance with self-isolation on the spread of an infectious disease; and iv) utilization and post-transplant survival of whole liver transplantation versus split liver transplantation.
Chapter 1 considers the vaccine pricing and subsidy allocation problem within group purchasing organizations, where members' purchasing power is combined to streamline the procurement process for certain products and benefit from volume discounts. However, the disparities in members' "ability to pay" and/or "willingness to pay" can be wide. In this work, we propose an optimization model that incorporates proxies for each country's willingness to pay and ability to pay. We conduct case studies based on data from Gavi (Gavi, the Vaccine Alliance) and PAHO (the Pan American Health Organization) member countries. The results show that the adjusted unit price disparity is non-increasing in the number of price tiers allowed. However, the biggest decrease in the adjusted price disparity occurs when switching to two-tier pricing from uniform pricing. Moreover, the benefit of tiered pricing in the Gavi group is more significant compared with that in the PAHO group.
In Chapter 2, we develop a generalized discrete optimization model to recommend personalized childhood immunization schedules. The model inputs include information about the diseases under consideration, a child's age and existing immunization history, and candidate vaccines being considered. The model can be used to solve both de novo scheduling (for newborns without any immunization history) and catch-up scheduling (for children under 18 years of age but late on one or more vaccinations), including the vaccine formulary selection considerations, in order to achieve a balanced combination of the following two goals: 1). to maximize the total immunization effectiveness of all recommended vaccines, and 2). to minimize the total number of clinic visits required to complete all the recommended pediatric vaccines.
When there are no available vaccines for a rapidly spreading infectious respiratory disease, diagnostic testing and self-isolation are important in reducing the transmission. Chapter 3 investigates the impact of diagnostic testing capacity and compliance with self-isolation on infectious diseases. The impact can depend on the interplay of the following factors: 1) how soon testing becomes available after the beginning of the pandemic, and 2) at what capacity; 3) compliance with isolation after testing positive; 4) compliance with isolation when experiencing symptoms, even in the absence of testing. We develop a compartmental model and simulate numerous scenarios using the dynamics of COVID-19 as a case study. The results highlight the benefits of the early start of testing and high compliance with isolation.
Chapter 4 focuses on liver transplantation. Split liver transplantation (SLT), where a single donor liver is divided to permit transplantation into two recipients, can expand the supply of donor organs available to adult patients and increase the availability of size-matched livers for pediatric candidates. In this study, we characterize the differences in donor/recipient features, analyze the matching dynamics, and compare the survival following split versus whole liver transplantation (WLT). The results in this study show that post-transplant survival of SLT and WLT recipients is similar (controlling for other factors that may impact patient survival), highlighting the importance of SLT for increasing the liver supply and potential benefits for both pediatric and adult candidates.