From the Journals

Few poorly prepped colonoscopies repeated within 1 year



Approximately one-third of colonoscopies with inadequate bowel preparation were repeated within 1 year despite current guidelines, according to data from a new study of more than 260,000 procedures.

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Previous studies have shown that poor bowel prep, which occurs in approximately 25% of colonoscopies, can lead to lesion miss rates of as much as 42%-48%, Audrey H. Calderwood, MD, an associate professor of medicine at Dartmouth-Hitchcock Medical Center, Lebanon, N.H., and colleagues wrote. However, factors affecting recommendations for repeat colonoscopies following poor bowel prep have not been examined.

In the study, published in Gastrointestinal Endoscopy, the researchers conducted a cross-sectional retrospective analysis of 260,314 colonoscopies reported to the GI Quality Improvement Consortium (GIQuIC) from 2011 to 2018. The review included adults aged 50-75 years in whom bowel preparation was deemed inadequate. The GIQuIC database defines adequate bowel preparation as “sufficient to accurately detect polyps greater than 5 mm in size,” the researchers noted. The procedures in this study were performed at 672 sites by 4,001 endoscopists, and the primary outcome was a recommendation for a repeat colonoscopy within 1 year.

In 31.9% of the procedures, the recommended follow-up interval for repeat colonoscopy was within 1 year, and there were no significant differences according to indication for the procedures (32.3% of screening and 31.2% of surveillance). Of these, 54.9% of patients received a follow-up interval of 1 year and 24.7% a follow-up interval within 3 months. Only 2.4% were advised they required no follow-up procedure.

The researchers found that patients with more severe disease had a higher likelihood of receiving a recommendation for follow-up colonoscopy within 1 year – 84% with adenocarcinoma, 51.8% with advanced lesions, and 23.2% with one to two small adenomas.

In the multivariate analysis, there were specific patient factors significantly associated with 1-year follow-up recommendations. The researchers found patients aged 70-75 years were less likely than younger patients (adjusted odds ratio, 0.96; 95% confidence interval, 0.93-0.98) to receive a 1-year follow-up recommendation; men were more likely than women (aOR, 1.04; 95% CI, 1.02-1.06) to receive a 1-year follow-up recommendation; and patients with adenocarcinoma findings more likely to receive a 1-year follow-up recommendation compared to those with no adenocarcinoma (aOR, 10.43; 95% CI, 7.77-13.98). In addition, they found patients residing in the Northeast and those whose procedure was performed by an endoscopist with an adenoma detection rate of at least25% were more likely to receive recommendations for a repeat colonoscopy within 1 year.

“The recommendation for repeat screening or surveillance colonoscopy within 1 year when the index colonoscopy has an inadequate bowel preparation is currently a quality measure in gastroenterology,” the researchers noted. “Although our study period started in 2011, when we looked at the time period of 2014 to 2018, which is after publication of guidelines of when to repeat colonoscopy after inadequate bowel preparation, there were still low rates of guideline-concordant recommendations.”

These overall low rates, which are consistent with other studies, may be due uncertainty on the part of the endoscopist in determining inadequate bowel prep based on evolving guidelines, the researchers noted. However, the higher frequency of recommendations for repeat procedures within 1 year for patients with advanced disease suggests that endoscopists are taking pathology into account.

The study findings were limited by several factors, including the lack of standardized assessment of bowel prep quality, variation in descriptions of bowel cleanliness, and lack of information on the primary factor in follow-up recommendations. However, the results were strengthened by the large sample size, the inclusion of multiple sites and providers, and the low volume of timely repeat procedures, which has clinical implications in terms of missed lesions, “including potential interval CRC [colorectal cancer],” the researchers said.


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