Impact of Regional Supply Factors on the Geographic Variation of Early-Stage Breast Cancer Surgical Use Open Access

Zhou, Jing (2015)

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Breast conservation therapy (BCT) and mastectomy are the two primary surgical treatments for early-stage breast cancer. In 1990, the National Institutes of Health Consensus Development Conference recommended BCT as the primary surgical treatment for early-stage breast cancer, due to the similar survival rate and higher quality of life of BCT, compared to mastectomy. However, BCT is underutilized and remarkable disparity in surgical rate exists across regions in the U.S.. Neither hospital factors nor patient-level factors such as patient age, race/ethnicity, education, hospital size, and teaching hospital, explain the geographic variation as examined by prior studies. This study aims to examine the association between hospital referral region (HRR)-level supply factors, particularly HRR-level supply of radiation oncologists and plastic/reconstructive surgeons, and the rate of mastectomy use for early-stage breast cancer at inpatient settings in HRRs. Multiple data sources were used to establish study samples: 2002-2011 Nationwide Inpatient Sample, 2000 Census, 2008-2012 5-year estimates American Community Survey, and 1996, 2006, and 2011 Dartmouth Health Atlas data. We employed a multivariate linear regression model for statistical analysis and conducted sensitivity analyses to examine the impact of using different years of HRR-level supply factors on the study results. The results showed that each additional radiation oncologists per 100,000 residents in HRRs can result in a 7.16 decrease in the rate of mastectomy use for early-stage breast cancer at inpatient settings in HRRs (P<0.05). Further, the supply of plastic and reconstructive surgeon is not associated with the rate of mastectomy use for early-stage breast cancer at inpatient settings in HRRs. This study contributes to existing literatures on examining early-stage breast cancer inpatient surgical care disparity from regional market supply perspective. Our findings also suggest that the supply disparity on radiation oncologists across regions may lead to the geographic variation on early-stage breast cancer surgical care at inpatient settings.

Table of Contents

Introduction --------1

Literature Review --------2

Early-stage Breast Cancer Surgical Care and its Geographic Variation in the U.S. --------2

Impact of Hospital and Patient Level Factors on the Geographic Variation ---------3

Impact of the Area-Level Market Supply Factors on the Geographic Variation --------4

Methodology --------6

Conceptual Framework --------6

Sample --------7

Data Sources --------7

Study Sample --------9

Measures --------9

Data Analysis --------13

Research Questions and Hypotheses --------13

Statistical Analysis --------14

Sensitivity Analysis --------14

Results --------16

Descriptive Analysis --------16

Statistical Analysis --------18

Sensitivity Analysis --------19

Discussion --------22

Summary of Findings --------22

Policy Implications --------22

Limitations --------24

Future Research --------26

Conclusion --------27

References --------28

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