Cuff-assisted colonoscopy: Should you be riding the mechanical enhancement wave?

Abstract

Colonoscopy is our best tool to identify precancerous polyps in the colon and to hopefully prevent colon cancer in our patients. However, no examination is perfect, and studies have shown adenoma miss rates of up to 24%.1Rex D.K. Cutler C.S. Lemmel G.T. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.Gastroenterology. 1997; 112: 24-28Abstract Full Text PDF PubMed Scopus (1323) Google Scholar We strive to improve adenoma detection rates (ADRs) by adjusting bowel preparation recommendations and slowing down withdrawal to a minimum of 6 minutes.2Barclay R.L. Vicari J.J. Doughty A.S. et al.Colonoscopic withdrawal times and adenoma detection during screening colonoscopy.N Engl J Med. 2006; 355: 2533-2541Crossref PubMed Scopus (1007) Google Scholar Furthermore, technological advancements such as high-definition imaging and virtual chromoendoscopy (narrow-band imaging) are geared toward improving ADRs. In recent years, we have added mechanical enhancement attachments, including caps, cuffs, rings, and balloons, the sole purpose being to increase surface area exposure for blind spots, such as proximal colonic folds. Cuff-assisted colonoscopy (CAC) aims to make us all elite colonoscopists. Approved by the U.S. Food and Drug Administration in 2012, the Endocuff (Olympus America, Center Valley, Penn, USA) is a disposable device that attaches to the tip of the colonoscope. The original version had 2 horizontal rows of flexible arms that collapse on insertion but splay out on withdrawal to engage and flatten haustral folds and increase mucosal area exposure, leading to improved visualization. In 2016, a meta-analysis demonstrated a higher ADR associated with first-generation CAC compared with standard colonoscopy alone (50.4% and 43.3%, respectively; n = 4387, P < .01).3Chin M. Karnes W. Jamal M.M. et al.Use of the Endocuff during routine colonoscopy examination improves adenoma detection: a meta-analysis.World J Gastroenterol. 2016; 22: 9642-9649Crossref PubMed Scopus (34) Google Scholar However, the studies involved in this meta-analysis varied in design (both retrospective and prospective studies were included), and the results had moderate heterogeneity with I2 = 55%; the largest randomized control trial (RCT) involved (n = 1063) demonstrated no significant difference in ADR. This same meta-analysis also reported adverse events associated with use of the Endocuff, including mucosal injury (2.3%), patient discomfort requiring removal of the device (2.0%), and loss of the device during withdrawal (0.52%) requiring retrieval. Perhaps the arrival of the second generation of CACs was a response to these accumulated shortcomings because it is less bulky with only one row of longer and softer flexible arms. In this issue of Gastrointestinal Endoscopy, Patel et al4Patel H.K. Chandrasekar V.T. Srinivasan S. et al.Second-generation distal attachment cuff improves adenoma detection rate: meta-analysis of randomized controlled trials.Gastrointest Endosc. 2021; 93: 544-553Abstract Full Text Full Text PDF Scopus (3) Google Scholar should be congratulated on allowing the colonoscopy community to better understand where CAC fits in daily practice. Does the new second-generation CAC improve colon polyp metrics? And more importantly, which endoscopists will benefit from it? The meta-analysis argues that CAC improves ADR compared with standard high-definition colonoscopy alone, especially in the screening and surveillance population.4Patel H.K. Chandrasekar V.T. Srinivasan S. et al.Second-generation distal attachment cuff improves adenoma detection rate: meta-analysis of randomized controlled trials.Gastrointest Endosc. 2021; 93: 544-553Abstract Full Text Full Text PDF Scopus (3) Google Scholar Our own experience with both first- and second-generation CACs has been a positive one overall. The flexible arms live up to the hype of flattening folds, exposing more colonic surface area. Our previous study showed that CAC outperformed the EndoRing (Olympus America, Center Valley, Penn, USA), full-spectrum endoscopy, and standard colonoscopy in ADR (64%), even with a high baseline ADR for the control group (56%, P < .001).5Rex D.K. Repici A. Gross S.A. et al.High-definition colonoscopy versus Endocuff versus EndoRings versus full-spectrum endoscopy for adenoma detection at colonoscopy: a multicenter randomized trial.Gastrointest Endosc. 2018; 88: 335-344.e2Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar More recently, we have found that endoscopic inspection time and overall withdrawal time was significantly shorter with the second-generation CAC, without compromise of ADR.6Rex D.K. Slaven J.E. Garcia J. et al.Endocuff vision reduces inspection time without decreasing lesion detection: a clinical randomized trial.Clin Gastroenterol Hepatol. 2020; 18: 158-162.e1Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar Although the addition of the cuff can lead to some minor resistance through the sigmoid colon, usually in the setting of diverticulosis, it is still easily traversable through the colon and has a comparable cecal intubation time with standard colonoscopy.6Rex D.K. Slaven J.E. Garcia J. et al.Endocuff vision reduces inspection time without decreasing lesion detection: a clinical randomized trial.Clin Gastroenterol Hepatol. 2020; 18: 158-162.e1Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar Thus, it was not surprising that the results of Patel et al’s meta-analysis mirror our own findings. Patel et al’s4Patel H.K. Chandrasekar V.T. Srinivasan S. et al.Second-generation distal attachment cuff improves adenoma detection rate: meta-analysis of randomized controlled trials.Gastrointest Endosc. 2021; 93: 544-553Abstract Full Text Full Text PDF Scopus (3) Google Scholar meta-analysis looks at 6 published articles and 2 abstracts from 7 countries. All studies were RCTs comparing the second-generation CAC with standard colonoscopy alone; both single- and multicenter studies were included. Patient populations varied. In some studies, only patients with a positive result for a fecal occult blood test (FOBT) were recruited, whereas others enrolled all adult patients who presented for elective colonoscopy. In 4 of the studies, ADR was the primary outcome; for the others, ADR was included in the secondary outcomes. The meta-analysis itself focused on ADR as the primary outcome and found that CAC was associated with a 4.2% increase in pooled ADR with a 1.12 risk ratio (P = .02) when compared with standard colonoscopy alone. Although there was moderate heterogeneity (I2 = 53%) and only 2 of the studies demonstrated a significant benefit of CAC, a few explanations are offered. The first is more straightforward; some of the studies had different primary outcomes (ie, withdrawal time, polypectomy time) and thus were not powered to detect differences in ADR. Second, a high baseline ADR may make it difficult to detect improvement even with CAC. This applies directly to the Bhattacharyya study, which evaluated 534 patients with positive results for the FOBT and included 4 endoscopists with an average baseline ADR (before the study) of 58.9%.7Bhattacharyya R. Chedgy F. Kandiah K. et al.Endocuff-assisted vs. standard colonoscopy in the fecal occult blood test-based UK Bowel Cancer Screening Programme (E-cap study): a randomized trial.Endoscopy. 2017; 49: 1043-1050Crossref PubMed Scopus (34) Google Scholar Although this explanation is plausible, we should also note that this study looked at polyp detection rate, not ADR, as the primary outcome. Given the endoscopists’ high baseline ADR, the study would have likely needed at least 2- to 3-fold more patients to be powered adequately to detect ADR differences, reverting back to the first explanation. The 2 studies that were able to detect significant differences were the 2 largest studies included in the meta-analysis with 2058 and 1772 patients; the patient populations in the other studies ranged from 170 to 820 patients (mean, 382; median, 285). The third factor is that some studies included patients with a positive result for the FOBT; this may inherently yield higher ADRs from which it is harder to detect improvements with CAC. Patel et al4Patel H.K. Chandrasekar V.T. Srinivasan S. et al.Second-generation distal attachment cuff improves adenoma detection rate: meta-analysis of randomized controlled trials.Gastrointest Endosc. 2021; 93: 544-553Abstract Full Text Full Text PDF Scopus (3) Google Scholar investigated this theory in an analysis looking at studies that involved only screening and surveillance colonoscopies but excluded patients with a positive result for the FOBT. They found an increased risk ratio of 1.21 and increased homogeneity of results (I2 = 3%) once those with a positive result for the FOBT were excluded from the metanalysis (P = .0004), supporting the idea that the FOBT population may be a confounder when investigating the efficacy of CAC. It is possible, however, that this variable can be overcome by increasing the sample size to provide adequate power. One of the most interesting parts of the meta-analysis is its stratification and analysis of studies based on endoscopists’ baseline ADRs from the standard colonoscopy control group (ADR <30%, <40%, <50%, ≥50%). What we see is an inverse relationship between endoscopists’ baseline ADR and their likely benefit from CAC (the lower ADR groups are associated with higher risk ratios and lower number needed to treat); Patel et al’s Supplementary Table 5 for screening and surveillance colonoscopies (patients with a positive result for the FOBT were excluded). This negative association is capped at an ADR of 50%, the level at which Patel et al defines as a very high detector. The idea that CAC may be beneficial for low detectors, and not high detectors, is echoed in Williet et al’s8Williet N. Tournier Q. Vernet C. et al.Effect of Endocuff-assisted colonoscopy on adenoma detection rate: meta-analysis of randomized controlled trials.Endoscopy. 2018; 50: 846-860Crossref PubMed Scopus (32) Google Scholar 2018 meta-analysis comparing CAC with standard colonoscopy. This meta-analysis differs from Patel et al’s because it includes (1) both retrospective and prospective studies and (2) both first- and second-generation CACs. Williet et al ran separate meta-analyses for studies where operators had ADRs <35% or >45% in the standard colonoscopy group. They found that studies with ADRs <35% have a higher risk ratio of 1.51 (P < .001), suggesting an increased ADR with CAC; in contrast, studies with ADRs >45% have a risk ratio of 1.01 (P = .87), indicating no difference in ADR between CAC and standard colonoscopy.8Williet N. Tournier Q. Vernet C. et al.Effect of Endocuff-assisted colonoscopy on adenoma detection rate: meta-analysis of randomized controlled trials.Endoscopy. 2018; 50: 846-860Crossref PubMed Scopus (32) Google Scholar The idea that CAC may benefit endoscopists with baseline ADRs up to 45% or 50% (depending on the meta-analysis of your choice) is quite provocative! In the United States, ADRs ≥30% for men and ≥20% for women have been established as a quality benchmark for colonoscopies.9Rex D.K. Schoenfeld P.S. Cohen J. et al.Quality indicators for colonoscopy.Am J Gastroenterol. 2015; 110: 72-90Crossref PubMed Scopus (246) Google Scholar In a 2014 retrospective study of patients in the Kaiser Permanente North California health system, ADRs for 314,872 colonoscopies performed by 136 gastroenterologists ranged from 7.4% to 52.5%. When separated into quintiles, about 80% of endoscopists had ADRs less than 33.5%.10Corley D.A. Jensen C.D. Marks A.R. et al.Adenoma detection rate and risk of colorectal cancer and death.N Engl J Med. 2014; 370: 1298-1306Crossref PubMed Scopus (909) Google Scholar Does this mean that most gastroenterologists should be converting to CAC? Although Patel et al’s4Patel H.K. Chandrasekar V.T. Srinivasan S. et al.Second-generation distal attachment cuff improves adenoma detection rate: meta-analysis of randomized controlled trials.Gastrointest Endosc. 2021; 93: 544-553Abstract Full Text Full Text PDF Scopus (3) Google Scholar study is encouraging, it is still based on RCTs with low-quality evidence according to the Grading of Recommendations, Assessment, and Evaluation (GRADE) guidelines. Because the flexible arms of the Endocuff are visible during CAC, endoscopists cannot be blinded and are susceptible to performance bias. Randomized crossover studies with back-to-back tandem colonoscopies with CAC versus standard colonoscopy may reduce some of this noise. However, the choice of whether to use the same endoscopist (who will be aware of the first colonoscopy’s findings and may become fatigued during the second colonoscopy) versus a different endoscopist (who may have different techniques and different baseline ADRs) presents new challenges. Another approach is to trend endoscopists’ ADRs throughout the study to ensure consistency is maintained. Lastly, studies evaluating long-term follow-up, based on surveillance colonoscopies, may be more applicable to our clinical practice. There is no one-size-fits-all rule in colonoscopy. Endoscopists should make sure that split-dose bowel preparation is done and that there is adequate withdrawal time. CAC shows the importance of increased colon surface area exposure, which is critical to improve lesion detection. However, the endoscopist must be aware of subtle mucosal changes, so as not to miss the lesion right in their field of view. Although we feel optimistic about incorporating CAC in screening and surveillance colonoscopies, further studies are needed to elucidate its role in improving ADR for this specific indication. Colonoscopy is changing, but will you? All authors disclosed no financial relationships. Second-generation distal attachment cuff improves adenoma detection rate: meta-analysis of randomized controlled trialsGastrointestinal EndoscopyVol. 93Issue 3PreviewMultiple randomized controlled trials (RCTs) using the second-generation distal attachment cuff device (Endocuff Vision; Olympus America, Center Valley, Pa, USA) have reported conflicting results in improving adenoma detection rate (ADR) compared with standard high-definition colonoscopy without the distal attachment. We conducted a systematic review and meta-analysis of RCTs to compare outcomes between second-generation cuff colonoscopy (CC) versus colonoscopy without the distal attachment (standard colonoscopy [SC]). Full-Text PDF