In a prospective study of almost 1,000 patients, this benefit was not influenced by polyp size, electrocautery setting, or concomitant use of antithrombotic medications, reported Heiko Pohl, MD, of Geisel School of Medicine at Dartmouth, Hanover, N.H., and colleagues.
“Endoscopic resection has replaced surgical resection as the primary treatment for large colon polyps due to a lower morbidity and less need for hospitalization,” the investigators wrote in Gastroenterology. “Postprocedure bleeding is the most common severe complication, occurring in 2%-24% of patients.” This risk is particularly common among patients with large polyps in the proximal colon.
Although previous trials have suggested that closing polyp resection sites with hemoclips could reduce the risk of postoperative bleeding, studies to date have been retrospective or uncontrolled, precluding definitive conclusions.
The prospective, controlled trial involved 44 endoscopists at 18 treatment centers. Enrollment included 919 patients with large, nonpedunculated colorectal polyps of at least 20 mm in diameter. Patients were randomized in an approximate 1:1 ratio into the clip group or control group and followed for at least 30 days after endoscopic polyp resection. The primary outcome was postoperative bleeding, defined as severe bleeding that required invasive intervention such as surgery or blood transfusion during follow-up. Subgroup analysis looked for associations between bleeding and polyp location, size, electrocautery setting, and medications.
Across the entire population, postoperative bleeding was significantly less common among patients who had their resection sites closed with clips, occurring at a rate of 3.5%, compared with 7.1% in the control group (P = .015). Serious adverse events were also less common in the clip group than the control group (4.8% vs. 9.5%; P = .006).
While the reduction of bleeding risk from clip closure was not influenced by polyp size, use of antithrombotic medications, or electrocautery setting, polyp location turned out to be a critical factor. Greatest reduction in risk of postoperative bleeding was seen among the 615 patients who had proximal polyps, based on a bleeding rate of 3.3% when clipped versus 9.6% among those who went without clips (P = .001). In contrast, clips in the distal colon were associated with a higher absolute risk of postoperative bleeding than no clips (4.0% vs. 1.4%); however, this difference was not statistically significant (P = .178).
“[T]his multicenter trial provides strong evidence that endoscopic clip closure of the mucosal defect after resection of large ... nonpedunculated colon polyps in the proximal colon significantly reduces the risk of postprocedure bleeding,” the investigators wrote.
They suggested that their study provides greater confidence in findings than similar trials previously conducted, enough to recommend that endoscopic techniques be altered accordingly. “[O]ur trial was methodologically rigorous, adequately powered, and all polyps were removed by endoscopic mucosal resection, which is considered the standard technique for large colon polyps in Western countries,” they wrote. “The results of the study are therefore broadly applicable to current practice. Furthermore, conduct of the study at different centers with multiple endoscopists strengthens generalizability of the findings.”
The investigators also speculated about why postoperative bleeding risk was increased when clips were used in the distal colon. “Potential explanations include a poorer quality of clipping, a shorter clip retention time, possible related to a thicker colon wall in the distal compared to the proximal colon,” they wrote, adding that “these considerations are worthy of further study.”
Indeed, more work remains to be done. “A formal cost-effectiveness analysis is needed to better understand the value of clip closure,” they wrote. “Such analysis can then also examine possible thresholds, for instance regarding the minimum proportion of polyp resections, for which complete closure should be achieved, or the maximum number of clips to close a defect.”
The study was funded by Boston Scientific. The investigators reported additional relationships with U.S. Endoscopy, Olympus, Medtronic, and others.
SOURCE: Pohl H et al. Gastroenterology. 2019 Mar 15. doi: 10.1053/j.gastro.2019.03.019.