Colorectal cancer (CRC) is the third-most diagnosed cancer after breast and lung cancer, and is the second leading cause of global cancer related deaths. 1 In 2023 in the United States, > 150,000 individuals were diagnosed with CRC and 52,000 died. 2
Colonoscopy is an effective CRC screening method and the lone method recommended for polyp surveillance. Inadequate bowel preparation (IBP) has been estimated to occur in about 6% to 26% of colonoscopies. 3,4 The prevalence varies based on a variety of comorbidities, including immobility, diabetes mellitus, neurologic disorders, and use of opioids, with more occurrences of IBP noted in older adult, non-English speaking, and male individuals. 4-6
The quality of bowel preparation is integral to the effectiveness of screening and surveillance colonoscopies. IBP has been associated with missed adenomas and significantly lower adenoma detection rates. 7-9 In particular, IBP is independently associated with an increased risk of CRC in the future. 3 Accordingly, the US Multisociety Task Force recommends repeat colonoscopies for individuals with IBP within 1 year. 10 Ensuring that these individuals receive repeat colonoscopies is an essential part of CRC prevention. The benefit of repeat colonoscopy after IBP is highlighted by a retrospective analysis from Fung and colleagues that showed 81% of repeat colonoscopies had adequate bowel preparation, with higher numbers of adenomas detected on repeat compared to initial colonoscopies. 11
Given the impact of bowel preparation quality on the diagnostic capability of the colonoscopy, adherence to guidelines for repeat colonoscopies in cases of IBP is paramount for effective CRC prevention. This study aims to measure the frequency of repeat colonoscopy after IBP and the factors associated with adherence to recommendations.
METHODS
Individuals who underwent colonoscopy at the Minneapolis Veterans Affairs Medical Center (MVAMC) from January 1, 2016, to October 19, 2021, were identified to allow for 400 days of follow-up from the index colonoscopy to the data collection date. During the COVID-19 pandemic, the colonoscopy procedure capacity was reduced by 50% from June 1, 2020, to December 1, 2020, delaying nonurgent procedures, including screening and surveillance colonoscopies.
Individuals who underwent colonoscopy for CRC screening or polyp surveillance, or following a positive fecal immunohistochemistry test (FIT) or virtual computed tomography colonoscopy were included. Patients with colonoscopy indications for iron deficiency anemia, gastrointestinal bleeding, disease activity assessment of inflammatory bowel disease, abdominal pain, or changes in bowel movement pattern were excluded. IBP was defined as recording a Boston Bowel Preparation Scale (BBPS) score of < 6, or < 2 in any segment, or described as poor or inadequate using the Aronchick scale.
Age, sex, race, marital status, distance to MVAMC, smoking status, comorbidities, and concurrent medication use, including antiplatelet, anticoagulation, and prescription opiates at the time of index colonoscopy were obtained from the Veterans Health Administration (VHA) Corporate Data Warehouse (CDW) using structured query language processing of colonoscopy procedure notes to extract preparation scores and other procedure information. The CDW contains extracts from VHA clinical and administrative systems that contain complete clinical data from October 1999. 12 Current smoking status was defined as any smoking activity at the time the questionnaire was administered during a routine clinic visit within 400 days from the index colonoscopy.