Center for Health Equity Research and Promotion

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Yu-Xiao Yang, MD, MSCE, CHERP Core Investigator and Attending Physician at the Crescenz VA Medical Center in Philadelphia, is also Associate Professor of Medicine and Associate Professor of Epidemiology in Biostatistics and Epidemiology, University of Pennsylvania Perelman School of Medicine and Attending Physician at the Hospital of the University of Pennsylvania.

Dr. Yang leads VA-funded research:

Comparative Effectiveness of Split-Dose Colonoscopy Bowel Preparation Regimens

The objective of this large-scale investigation is to compare the real-world effectiveness of the two most commonly used split-dose colonoscopy bowel preparation regimens in the US (i.e., 4L PEG and 2L MiraLAX/Gatorade) with respect to the completion rate of scheduled colonoscopies, adenoma detection rate and secondarily preparation quality, cancellation/no-show rate and patient-oriented outcomes (e.g., willingness to repeat the preparation).

By identifying a colonoscopy bowel preparation regimen which is the most effective in real-world VA practice and can be immediately implemented on a VA-wide scale, the proposed study will maximize the effectiveness of colonoscopy in reducing colorectal cancer (CRC) risk among veterans, increase veteran satisfaction, and reduce VA healthcare cost.

Colorectal cancer (CRC) is a leading cause of cancer-related death among Veterans. Colonoscopy can effectively reduce CRC incidence and mortality. However, non-adherence to screening colonoscopy substantially undermines this benefit. Existing evidence indicates that a disagreeable bowel preparation is a leading barrier to completing a colonoscopy from the patients' perspective. The taste and the volume of the bowel preparation determine patient tolerability and compliance to the preparation instructions, which in turn affects the incompletion (e.g., cancellation/no-show/reschedule) rate of scheduled colonoscopies as well as the effectiveness of the completed colonoscopies and patient satisfaction. The two most commonly used preparations currently in the US are the split-dose 4L polyethylene glycol (PEG) and the split-dose 2L MiraLAX/Gatorade preparations. While a high-volume regimen may in theory be more effective than a lower volume one, it may be associated with lower tolerability and adherence in real-world practice. Three small trials have compared these two preparations. However, data from these explanatory trials cannot inform policy decisions because they were conducted under artificial conditions, restricted among narrow patient populations, and most importantly not designed to capture the full impact of bowel preparation on the completion rate or effectiveness of colonoscopy. This VA trial is designed to address this critical knowledge gap.

Dr. Yang's research program focuses on gastrointestinal cancer epidemiology, pharmacoepidemiology and gastrointestinal epidemiology. He has several ongoing R01-level studies, funded by the National Institutes of Health and Veteran's Administration, which reflect these themes. These issues have far-reaching implications for cancer prevention for the enormous population of diabetes patients.