A Population-Based Study of Colon Cancer Treatment Quality in Georgia: Race, Residential Segregation and Rural-Urban Residence Open Access

Hopson, Sari De'Ann (2012)

Permanent URL: https://etd.library.emory.edu/concern/etds/9019s268p?locale=en
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Abstract

Abstract
A Population-Based Study of Colon Cancer Treatment Quality in Georgia:
Race, Residential Segregation and Rural-Urban Residence

Prognosis of colorectal cancer, the third most common invasive malignancy in the US,
depends on timely diagnosis and on the receipt of appropriate treatment. Clinical factors strongly
influence treatment; however, studies also demonstrate the impact of non-clinical factors. This
dissertation examined the role of non-clinical factors (patient race and residential characteristics)
in the receipt of quality colon cancer treatment. Treatment quality was assessed in terms of
surgeon training and experience and the receipt and completion of adjuvant chemotherapy.
Three questions motivated this project:
1. Are the qualifications of colon cancer surgeons associated with characteristics of their
Medicare patient population?
2. Do patient race and/or rural-urban residence influence the receipt of adjuvant
chemotherapy among Medicare patients with stage III colon cancer; if so, are these
associations explained by residential segregation?
3. Is patient race associated with the receipt and completion of adjuvant chemotherapy
among stage III colon cancer patients in predominantly rural Southwest Georgia
(SWGA)?
For question one, we found that percentages of black patients were higher for less qualified
surgeons and lower for most qualified surgeons. The patients of most qualified surgeons resided
in less racially segregated census tracts. These findings indicate that non-clinical patient factors
may affect the quality of colon cancer care among Medicare patients.
For question two, neither patient race nor residential segregation measures were associated
with receipt of adjuvant chemotherapy among Georgia Medicare colon cancer patients. Receipt
of chemotherapy was less common among patients who were older, non-married and had co-
morbid illnesses. These findings suggest that receipt of chemotherapy is more strongly
influenced by possible contraindications to chemotherapy (advanced age and comorbidities) than
by social factors.
For question three, race was not a significant predictor of chemotherapy receipt among
Southwest Georgia colon cancer patients; however, white patients completed adjuvant
chemotherapy less often than black patients. Chemotherapy receipt was higher among younger
patients and those receiving therapy at accredited cancer facilities. Chemotherapy completion was
more common among married patients and those with private insurance. The observed racial
disparity in treatment completion may be explained by differences in chemotherapy tolerance,
toxicity and patient support.


A Population-Based Study of Colon Cancer Treatment Quality in Georgia:
Race, Residential Segregation and Rural-Urban Residence

By
Sari De'Ann Hopson
B.S.P.H & B.A., University of North Carolina, Chapel Hill, 2003
M.S.P.H., Emory University, 2005
Advisor: Michael Goodman, MPH, MD
A dissertation submitted to the Faculty of the
James T. Laney School of Graduate Studies of Emory University
in partial fulfillment of the requirements for the degree of
Doctor of Philosophy in Epidemiology
2012

Table of Contents



Table of Contents

Table of Contents .............................................................................................................. vii
List of Tables ................................................................................................................. xii
List of Figures .............................................................................................................. xiii
Introduction ......................................................................................................................... 1
Chapter 1: Understanding Colorectal Cancer ..................................................................... 5
Epidemiology of Colorectal Cancer ................................................................................ 5
Etiology of Colorectal Cancer ......................................................................................... 7
Anatomy and Physiology of the Large Intestine ............................................................. 8
Diagnosis and Staging of Colorectal Cancer ................................................................... 9
Colon Cancer Treatment ............................................................................................... 10
Chapter 2: Measures and Determinants Of Treatment Quality: A Literature Review ..... 12
Evaluating Health Care Quality .................................................................................... 12
Residential Segregation ................................................................................................. 13
Segregation and Cancer Care ........................................................................................ 16
Defining Rural-Urban Status for Epidemiology Research ............................................ 17
Rural-Urban Disparities in Colon Cancer Care ............................................................. 19
Black-White Racial Disparity in Receipt of Colorectal Cancer (CRC) Adjuvant
Therapy .......................................................................................................................... 20



Clinical and Non-Clinical Determinants of Adjuvant Therapy for Colon Cancer ........ 25
Physician Characteristics, Residential Characteristics and Patient Demographics ....... 27
Physician Characteristics, Cancer Treatment and Outcomes ........................................ 29
Hospital Characteristics, Patient Characteristics, Cancer Care and Outcomes ............. 30
Quality of Adjuvant Chemotherapy Data Reported by Cancer Registries Medicare ... 30
Chapter 3: Source Population ........................................................................................... 34
Residential Segregation ................................................................................................. 34
Rural-Urban Residence ................................................................................................. 34
Racial Distribution ........................................................................................................ 35
Chapter 4: Overview of Data Sources .............................................................................. 36
Chapter 5: Is the level of training and/or experience of colon cancer surgeons associated
with characteristics of their patient population? ............................................................... 38
Abstract: ........................................................................................................................ 38
Introduction ................................................................................................................... 39
Methods ......................................................................................................................... 39
Results ........................................................................................................................... 48
Discussion ..................................................................................................................... 50
References: .................................................................................................................... 53
Appendix ........................................................................................................................... 63



Surgery Claims Codes ................................................................................................... 63
Variable Categorization Descriptions ........................................................................... 67
Modeling Strategy ......................................................................................................... 69
Chapter 6: Receipt of Chemotherapy among Stage III Colon Cancer Patients: Race,
Rural-Urban Residence and Residential Segregation ....................................................... 72
Abstract ......................................................................................................................... 72
Introduction ................................................................................................................... 73
Methods ......................................................................................................................... 73
Results ........................................................................................................................... 81
Discussion ..................................................................................................................... 82
References ..................................................................................................................... 86
Appendix ......................................................................................................................... 100
Chemotherapy Claims Codes ...................................................................................... 100
Modeling Strategy ....................................................................................................... 103
Multivariate GEE Logistic Models ............................................................................. 103
Chapter 7: Racial Differences in Receipt and Completion of Adjuvant Chemotherapy
among Stage III Colon Cancer Patients in Southwest Georgia ...................................... 110
Abstract ....................................................................................................................... 110
Introduction ................................................................................................................. 111



Methods ....................................................................................................................... 112
Results ......................................................................................................................... 116
Discussion ................................................................................................................... 118
References ................................................................................................................... 122
Appendix ......................................................................................................................... 132
Definitions and calculations of segregation indices .................................................... 132
Modeling Strategy ....................................................................................................... 134
Multivariable Logistic Models .................................................................................... 135
Chapter 8: Dissertation in Context, Limitations, Strengths and Recommendations for
Future Studies ................................................................................................................. 138
Health Care Quality and Patient Race ......................................................................... 139
Health Care Quality and Rural/Urban Residence ....................................................... 140
Health Care Quality and Segregation (Racial and Income) ........................................ 140
Limitations .................................................................................................................. 141
Strengths ...................................................................................................................... 142
Recommendations for Future Studies ......................................................................... 143
References ................................................................................................................... 143
Appendices ...................................................................................................................... 147
A: Anatomy of the Large Intestine ................................................................................. 148

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