Sociodemographic Disparities in Colorectal Cancer Screening, Interval Colorectal Cancers and Quality of Colonoscopy Open Access

Fedewa, Stacey Ann (2016)

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Use of recommended colorectal cancer (CRC) screening tests in the United States is well below nationwide goals, especially among racial/ethnic minorities and individuals with lower socioeconomic status (SES). Recent changes in health insurance policy and increasing use of organized screening approaches are expected to improve CRC screening coverage; however how these changes affect socioeconomic and racial/ethnic disparities in receipt of screening is not known. In addition, some screened persons may develop the so-called "interval CRCs", which are defined as cancers that develop after a negative colonoscopy but before the next recommended test. Little is known if the risk of interval cancers differs by race/ethnicity. The goal of this dissertation was to examine CRC screening utilization and interval CRC occurrence by sociodemographic factors. This goal was achieved addressing three specific aims. Aim 1 was to examine CRC screening prevalence before and after the enactment of an Affordable Care Act (ACA) provision that removed costs for CRC screening tests. Aim 2 was to evaluate the time to receipt of CRC screening in newly age-eligible adults within Kaiser Permanente Northern California's (KPNC) organized screening program. Aim 3 was to assess variations in interval CRC incidence according to race/ethnicity. Data from the National Health Interview Surveys (NHIS, 2008,2013), KPNC medical records (2007-2012), and Surveillance Epidemiology and End Results (SEER)-Medicare linked data (2002-2011) were used in this dissertation. Three different study designs (cross-sectional for Aim 1, retrospective cohort for Aim 2, matched case-control for Aim 3) with multivariable statistical models were used to examine research questions. Increases in CRC screening after the ACA removed cost-sharing were observed in only blacks and whites, but not in Hispanics; changes were modest and not statistically significant after adjusting for other sociodemographic factors. Among adults newly eligible to be screened in KPNC's organized screening program, over 70% of enrollees initiated screening within 2 years of their 50th birthday and relative to whites and the likelihoods of completing CRC screening were similar in blacks, 5% lower in Hispanics and 13% higher in Asians. In terms of interval CRCs, compared to whites, interval CRC incidence was significantly higher in blacks, after accounting for a quality of colonoscopy metric and other sociodemographic factors. These studies suggest that policies aimed at increasing CRC through waiver of costs have only marginally improved CRC screening overall and may not have eliminated sociodemographic disparities, though racial disparities in CRC screening initiation among newly eligible adults within an organized program were modest. Furthermore, even if equitable rates of screening rates are achieved, the incidence of blacks may be greater than whites as a result of interval CRCs.

Table of Contents

Chapter 1 Introduction. 11

Chapter 2 Literature Review. 17

Chapter 3 Data Sources and Study Framework. 51

Chapter 4 Changes in CRC screening before and After the Affordable Cancer Act (Aim 1). 66

Chapter 5 Time to Colorectal Cancer Screening by Race/Ethnicity in Kaiser Permanente California (Aim 2). 90

Chapter 6 Interval Colorectal Cancers, Race/Ethnicity and Physician Polyp Detection Rate in Medicare Enrollees (Aim 3). 120

Chapter 7 Conclusions and Future Directions. 153

References. 159

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