CHARLOTTE, N.C.—Colonoscopies performed after abnormal fecal immunochemical DNA tests are associated with greater detection of lesions, longer withdrawal times and recommendations for shorter intervals after a normal exam compared with those done after positive results on the fecal occult blood test or those performed in average-risk people.
These results come from an analysis of a large database, presented at the 2022 annual meeting of the American College of Gastroenterology (ACG) by Jason A. Dominitz, MD, MHS, of VA Puget Sound Health Care System and the University of Washington, in Seattle (abstract S252).
“Despite lower specificity of FIT DNA versus FOBT, endoscopists seem to have greater concern for missed pathology” in negative colonoscopies after positive findings on the FIT DNA (multitarget stool DNA) test (Cologuard, Exact Sciences), “leading to significantly shorter recommended surveillance,” said Dr. Dominitz, the executive director of the Veterans Health Administration’s National Gastroenterology and Hepatology Program.
Risk-Related GI Care
Dr. Dominitz and his team aimed to determine the adenoma detection rate (ADR) and other lesion detection rates during follow-up colonoscopy and assess endoscopist behavior related to withdrawal time and recommendations after a negative colonoscopy.
They looked at three types of colonoscopy indications: screening for average-risk individuals, follow-up colonoscopy in patients who were FIT DNA-positive and follow-up after abnormal findings on the FOBT (guaiac or FIT).
“We hypothesized that when doctors are faced with a patient who has a history of a positive FIT DNA test, they behave differently—for example, they do a more careful exam,” Dr. Dominitz said.
The analysis was based on more than 1.8 million colonoscopies performed in 727 endoscopy suites, uploaded to the GI Quality Improvement Consortium database from 2019 to 2022. The analysis included 1,760,840 screening colonoscopies, 23,046 colonoscopies after FIT DNA positivity and 26,455 colonoscopies after FOBT positivity. The investigators restricted the analysis to high-quality exams (reaching the cecum, with adequate bowel preparation). The average ADR rate of the participating endoscopists was 39%.
Exams done in FIT DNA-positive patients were associated with a higher ADR than those done for average-risk screening (59.3% vs. 39.3%; P<0.0001) or in FOBT-positive patients (53.8%; P<0.0001). Colonoscopies after positive FIT DNA results also were associated with greater detection of advanced neoplasia compared with screening colonoscopies done in average-risk patients (22.2% vs. 7.6%; P<0.0001) or in patients with FOBT positive results (17.4%; P<0.0001). Significant differences also were observed for the detection of sessile serrated lesions and adenocarcinoma, Dr. Dominitz reported.
In addition, among patients without abnormal pathology on follow-up colonoscopy, withdrawal time was almost one minute longer for the FIT DNA-positive patients than for the other two groups (P<0.0001 for both). “They’re worried, so they are spending more time looking,” Dr. Dominitz said.
Inappropriate Recommendations After Negative Findings
Importantly, among patients 50 to 65 years of age without pathology and with few comorbidities, the appropriate 10-year colonoscopy interval was recommended for 80.1% of FIT DNA-positive patients compared with 87.2% of screening patients and 86.5% of FOBT-positive patients. Approximately 16% of the FIT DNA-positive group was told to return in four or five years, and almost 4% were asked to come back within three years.
“These were average-risk individuals, but the endoscopists’ behavior after a negative colonoscopy was different. When there is nothing found, we should recommend a follow-up exam at 10 years, but FIT DNA-positive patients were told to come back in 10 years only 80% of the time, versus 87% for the other groups. We don’t know why the providers recommended coming back sooner without findings. All I can imagine is that they are more worried about the FIT DNA-positive patients. These were all high-quality exams, but they apparently were not trusting them,” Dr. Dominitz said.
Implications for Care
A follow-up colonoscopy is only needed once every 10 years when the index exam is normal, “but we’re seeing that that doesn’t happen,” Dr. Dominitz said. Even in a screening situation, 13% of the time patients are told to come back sooner—and it’s a bigger problem in the FIT DNA-positive population,” he said. “We need to do a better job getting providers to be comfortable recommending that patients come back in 10 years. The results have downstream implications from a healthcare system—i.e., resource—perspective.”
Folasade (Fola) P. May, MD, PhD, MPhil, an associate professor of medicine at the David Geffen School of Medicine at the University of California, Los Angeles, and the director of the Melvin and Bren Simon Gastroenterology Quality Improvement Program, selected the poster for group viewing with members of her laboratory because of its importance.
Dr. May said the finding of associations between positive FIT DNA and ADR and with advanced neoplasia offer evidence that stool-based screening works. “It helps us find individuals with adenomas and cancers,” she told Gastroenterology & Endoscopy News.
“The finding that colonoscopists spent significantly longer time examining the colon of individuals with positive FIT DNA results is also consistent with what I would expect. When we know that a patient has an abnormal stool-based screening test result, we become quite concerned that there may be an adenoma or cancer, and paranoid that we might miss it,” she added.
“The other message I’m taking away from this study is that colonoscopists don’t yet feel comfortable with a 10-year interval recommendation after a negative colonoscopy,” Dr. May said. “We need to do better to avoid unnecessary procedures.”
—Caroline Helwick
Dr. Dominitz reported no relevant financial disclosures. Dr. May reported a financial relationship with Exact Sciences, Freenome and Medtronic.
This article is from the January 2023 print issue.