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Dissertation
Spatial accessibility to healthcare in the COVID-19 era: a relational approach to the effects of context on disparities in infection and mortality
Doctor of Philosophy (Ph.D.), Drexel University
Jun 2025
DOI:
https://doi.org/10.17918/00011052
Abstract
Background: The COVID-19 pandemic disrupted healthcare systems, exposed and magnified long-standing health inequities in the United States. While substantial research has addressed individual risk factors for COVID-19 outcomes and disparities, the role of spatial access to healthcare infrastructure remains underexamined. This dissertation investigates how spatial accessibility to healthcare facilities shaped disparities in infection and mortality, applying a relational approach that considers multilevel risks across various geographic and temporal scales. Methods: This dissertation comprises three interrelated studies. Study 1 employed county-level data and overdispersed Poisson models to identify specific types of healthcare facilities predictive of COVID-19 mortality rates in 3,106 U.S. counties (2020-2021). Study 2 used individual-level data from 10,089 REGARDS participants nested within the C4R cohort to examine associations between healthcare facility access and COVID-19 infection risk via logistic regression. Study 3 leveraged 20 years of longitudinal mortality data (2003-2022) from REGARDS (N = 28,361) and applied Poisson models with spline and interaction terms to assess whether the timing of pandemic onset modified associations between healthcare access and all-cause mortality. Results: Across studies, the absence of specific healthcare facility types, including pharmacies/drugstores, offices & clinics of health practitioners, urgent care, and residential care, was associated with elevated risk of infection and mortality. These associations intensified post-pandemic onset, with evidence of effect modification on both additive and multiplicative scales. Diverging mortality trends by accessibility suggest that spatial inequities in infrastructure contributed to widening health disparities during the COVID-19 era. Discussion: This dissertation highlights the structural role of spatial accessibility in shaping pandemic-related outcomes and demonstrates the value of integrating fine-scale, time-varying exposure measures with rigorous methods and analytic designs. Findings support the use of spatial access metrics as equity-relevant indicators and reinforce the need for place-based health policies that ensure healthcare resources are equitably distributed in anticipation of future public health crises.
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Details
- Title
- Spatial accessibility to healthcare in the COVID-19 era
- Creators
- Edwin M. McCulley
- Contributors
- Usama Bilal (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xii, 135 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Dana and David Dornsife School of Public Health; Epidemiology and Biostatistics; Drexel University
- Other Identifier
- 991022058734204721