Date of Award


Document Type

Open Access Dissertation


Health Services and Policy Management

First Advisor

Sudha Xirasagar


Colorectal cancer (CRC) is the 3rd most prevalent cancer and 2nd leading cause of cancer death in the U.S. Colonoscopies have been recommended as the preferred screening method to prevent cancer by removing polyps before they transform into cancer. Although colonoscopy every 10 years is considered to be the preferred screening method, it is not perfect mainly owing to the variable quality of screening colonoscopy under community-based practice conditions. Although the effectiveness of colonoscopy in preventing CRC is documented, screening colonoscopy coverage in the US population remains low. This is partly due to low colonoscopy capacity due to a shortage of gastroenterologists (GIs), the major physician type performing screening colonoscopies. When the supply of GIs is limited, trained primary care physicians (PCPs) could be a solution to address the gap, especially for underserved populations and regions (including rural areas). Another reason for low uptake of colonoscopy could be perceptions of colonoscopy as an invasive and potentially painful procedure, particularly concerns about partially or unsedated colonoscopy, limiting its protective potential.

In this study, our setting is a community-based facility, which has followed a uniform protocol for almost all but not all physicians for 12 years. In order to evaluate the protocol elements, we explore the association between the 2-person technique pioneered by this center, and sedation type and the quality of colonoscopy outcomes.

The aim of this study was to evaluate the quality of colonoscopies. We hypothesized that colonoscopy quality may be enhanced by applying the 2-person technique protocol relative to solo technique performance, and with deep sedation by propofol relative to the conventional Midazolam-meperdine combination.

Our findings suggest that an innovation of a hands-on 2-person technique is highly associated with superior colonoscopy performance and lesion detection outcomes, and that by every discriminating measure, the results with the 2-person technique are superior, and consistent across measures. Propofol sedation might have improved the colonoscopy quality though not significantly when modified by the bowel preparation status. What we found is the bowel preparation actually plays an essential role in the colonoscopy performance and outcome quality indicators.


© 2013, Yi Jhen Li