The benefits and harms of visual cancer screening exams for adults can’t be adequately assessed with current evidence, according to new recommendations from the U.S. Preventive Services Task Force. The recommendations were published online July 26 in JAMA.

“Several recent prospective studies of one-time colonoscopies have demonstrated an association between higher BBPS (Boston Bowel Preparation Scale) scores and higher polyp and adenoma detection rates,” wrote Matthew A. Kluge, MD, of Boston University Medical Center, and his colleagues.

“We hypothesized that the BBPS could predict the likelihood of missed polyps based on initial BBPS segment scores among a large consortium of gastroenterology practices throughout the United States, thereby providing evidence to inform recommendations for repeat colonoscopy after less-than-perfect bowel preparation,” they said.

The researchers reviewed data from 335 pairs of colonoscopy exams in which the second exam (C2) was performed within 3 years of the first exam (C1). The primary endpoint was the detection of polyps and advanced polyps among colon segments at C2 stratified by BBPS scores at C1 (Gastrointest Endosc. 2017 Jun 22. doi: 10.1016/j.gie.2017.06.012 ).

Overall, patients with inadequate bowel prep were significantly more likely than those with adequate prep to be male (71% vs. 60%) and younger (average age, 59 years vs. 61 years). In addition, patients with inadequate prep at C1 were significantly more likely to have C2 for an indication of screening, while patients with adequate prep at C1 were significantly more likely to undergo C2 for surveillance.

In a multivariate model, the risk of advanced polyps at C2 was significantly higher for patients who had advanced polyps at C1 (odds ratio, 3.5), but inadequate BBPS scores at C1 had no significant impact on advanced polyp risk at C2. The risk of advanced polyps at C2 increased slightly with each year of age (OR, 1.1), but was not impacted by sex or time between C1 and C2 visits.

In addition, polyps at C2 were significantly more likely in patients with inadequate examinations at C1 vs. adequate C1 exams (18% vs. 7%).

The study’s strengths include the use of a large database, but limitations include lack of information about pathology and the use of surrogate measures of polyp size, the researchers noted. However, the results highlight the importance of proper bowel prep and support previous observations that “individuals with a BBPS segment score of 0 and 1 may be at increased risk for missed polyps, especially if advanced polyps are detected,” they said.

The study was supported in part by the Clinical Outcomes Research Initiative (CORI) and by the National Institutes of Health, and CORI has received infrastructure support from companies including AstraZeneca, Bard International, Endosoft, Ethicon, GIVEN Imaging, Pentax USA, and ProVation. Lead author Dr. Kluge had no financial conflicts to disclose.