Spatial Associations between Measures of Public Transportation and Diabetic Foot Ulcer Outcomes in the State of Georgia – 2016-2019 Restricted; Files Only

Abstract

Background: Diabetic foot ulcers (DFUs) are the leading cause of preventable limb loss in the United States. Timely access to multidisciplinary care for DFUs is crucial for preserving limbs, and transportation plays a pivotal role in ensuring such access. This study aims to investigate the association between transportation vulnerability and DFU-related amputations in the state of Georgia, focusing on the use and availability of public transportation at the ZIP code level in combination with socio-economic (SES) measures.

Methods: Visit-level data from the Healthcare Cost and Utilization Project (HCUP) database in Georgia from the years 2016-2019 were obtained, and we defined DFUs and amputations through ICD-10 diagnosis and procedure codes. Transportation variables were obtained from publicly available sources and aggregated to the ZIP code level. Bayesian spatial-temporal models were employed to assess the associations between transportation exposures and DFU- related amputations within each quartile of SES indicators at the ZIP code level.

Results: Within the HCUP database, there were 3,315,384 total encounters, 114,606 cases of DFUs, 21,388 cases of DFU-related amputations between the years 2016-2019 in the state of Georgia. Analysis revealed spatial disparities in DFU-related amputations, with higher risks observed in areas with more limited transportation resources. Specifically, a 261-meter increase in distance to transit stop was associated with higher amputation risk among ZIP codes in the highest quartile of vehicle non-ownership (RR = 1.12, 95% CI: 0.89-1.40) and in the highest quartile of percentages of poverty status (RR = 1.37, 95% CI: 0.94- 2.00). Conversely, an $0.06 increase in per capita expense on public transportation was associated with a lower amputation rate overall (RR = 0.65, 95% CI: 0.59-0.72) and across all stratifications of SES.

Conclusion: This study contributes to the understanding of transportation accessibility in managing diabetes care and reducing the burden of DFU-related amputations. Improving transportation infrastructure, particularly in socioeconomically disadvantaged areas, may help alleviate disparities in health outcomes. Future research should explore longitudinal study designs to further explain these relationships and examine interventions to improve healthcare access.

Table of Contents

Table of Contents

Introduction.................................................................................................................................... 1

Methods .......................................................................................................................................... 2 

Georgia State-Wide Hospital Billing Databases....................................................................... 2

Transportation and Socio-Economic Status Variables............................................................. 3

Statistical Analysis................................................................................................................... 4 

Results ............................................................................................................................................ 6

Discussion ...................................................................................................................................... 9

References .................................................................................................................................... 12

Tables and Figures....................................................................................................................... 14

Supplemental Materials ............................................................................................................... 18 

Supplemental Figures........................................................................................................... 18

Supplemental Tables ............................................................................................................ 24

Appendix....................................................................................................................................... 36

About this Master's Thesis

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• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Rollins School of Public Health
Department	Biostatistics
Subfield / Discipline	Biostatistics - MPH & MSPH
Degree	M.S.P.H.
Submission	Master's Thesis
Language	English
Research Field	Biology, Biostatistics Health Sciences, Epidemiology Health Sciences, Public Health
Keyword	Diabetic Foot Ulcers Transportation Vulnerability
Committee Chair / Thesis Advisor	Howard H. Chang, Emory University
Committee Members	Marcos C. Schechter, Emory University

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