10.1055/a-1533-6183Cap-assisted colonoscopy first appeared in Japan in the 1990 s and since then, its
use for diagnostic colonoscopy has been slowly gaining acceptance, supported by technical
developments and new devices showing incremental benefit in terms of adenoma yield,
an established surrogate for colorectal cancer-related mortality [1]. While the first-generation Endocuff has not been shown to be effective in this
context [2] and aggregate gains from Endocuff-assisted colonoscopy (EAC) have been considered
to be equivocal in comparison to standard colonoscopy (SC) [3] and transparent cap-assisted colonoscopy (TAC) [4]
[5], recent high-quality evidence supports the utility of the next-generation Endocuff
Vision (ECV, Olympus Japan) in the context of colon cancer screening [6]
[7].
Endocuff Vision (ECV, Olympus Japan) is a single-use, add-on device that can be applied
to the tip of a standard colonoscope. It has multiple finger-like protrusions that
extend outside of the cap, are compressed on insertion of the colonoscope, and then
open on withdrawal to facilitate exposure of mucosal folds during inspection.
In the current issue of EIO, Forbes et al. [8] present a real-world evaluation of ECV and its utility and uptake in an uncontrolled
environment within a large screening-based colonoscopy practice in Canada. While any
non-randomized study is open to risk of bias, this observational cohort study included
a large sample and its results are broadly consistent with data from previous randomized
controlled trials (RCTs). The authors employed several statistical approaches to minimize
these limitations and their results are broadly consistent across the primary outcome
(adenoma detection rate [ADR]) and a range of relevant secondary outcomes. Importantly,
there appears to have been no adverse impact on procedure- and patient-related performance
measures.
The study design related to a 1-year period in which ECV use in a single high-volume
center was incorporated into daily practice, focusing on a selected cohort of screening-related
indications for colonoscopy. The study considered two time periods: a baseline period
during which ECV use was discretionary, followed by a 1-month training period (data
not analyzed from this period) and then an ECV period, during which use of ECV was
the default (caps applied by endoscopy unit staff in all cases) but remained at the
discretion of the endoscopist (high uptake > 70 %). The study included a high number
of endoscopists (40 total, gastroenterologists and colorectal surgeons) with varying
degrees of volume, subspecialty, and baseline ADRs.
While the use of ECV was associated with an increased likelihood of detecting at least
one adenoma (AOR 1.24, CI 1.1–1.4), the likelihood of detecting sessile serrated lesions
(SSLs) was not statistically significant (AOR 1.13, CI 0.97–1.31) but did seem to
improve in subgroup analyses (non-FIT positive). Further, the benefit in terms of
ADR appears to be confined to polyps < 10 mm. A propensity score analysis (ECV group
only) did see a maintained benefit in terms of ADR and SSL detection rate, although
with wider confidence intervals approaching unity in both subgroups.
Notwithstanding the benefit in terms of diagnostic yield, procedural parameters (cecal
intubation, withdrawal times, procedure duration, sedation use, and patient comfort)
were not affected adversely by ECV use. Removal of the ECV was required in 4.6 % of
cases, an acceptable level and predominantly in the left colon, thus presumably not
affecting procedure times significantly for patients in whom ECV removal was necessary.
Existing data tell us that ADR varies widely among endoscopists and this point is
highlighted by the authors in their discussion. While low-cost quality bundles [9] and cheaper adjuncts such as narrow-band imaging [10] are proven to improve ADR, widescale adoption of these measures can prove challenging
outside of specialist settings [11]. Like any quality improvement intervention, the greatest benefit for ADR is expected
by improving detection rates for low detectors, rather than adding small increments
to endoscopists already performing at a high level. ECV further appears to improve
ADR while reducing inspection times, suggesting more detection per unit time and potentially
leading to enhanced efficiencies in endoscopy units.
We expect newer adjuncts, such as artificial intelligence (AI) detection software,
to support ADR in general endoscopic practice in the near future. However, these tools
are still limited by the level of mucosal exposure presented to them by the endoscopist.
Mucosal exposure percentages are now quantifiable by AI software and are likely to
become a relevant measure of quality for colonoscopy as AI systems become more widely
applied. Due to its mechanism of action, ECV has the potential to increase mucosal
exposure and it is, therefore, possible that the addition of simple adjuncts like
ECV to traditional quality bundles and supported by AI systems will provide the optimal
setup to ensure high-level ADRs across the next generation of endoscopists.
Other questions remain to be answered for ECV-assisted colonoscopy. Therapeutic procedures
were not analyzed in this study and planned advanced polypectomy/EMRs were excluded.
While this was done for valid reasons in line with the study design, it remains unknown
if ECV is useful in a therapeutic setting, either in terms of shortening procedure
time or improving technical/procedural outcomes. The authors did not present any data
on ileal intubation, an area in which ECV may import some limitations, and it is likely
due to the nature of the cohort (screening) and lack of clinical indication for ileal
intubation. Finally, the role of ECV-assisted colonoscopy in supporting detection
of SSLs remains unclear, although conclusions from RCT data guard against its application
in surveillance of serrated polyposis syndrome [12]. ECV application may need to be considered carefully in a more diverse endoscopic
practice than that presented in this study.
Given the consistent benefit for ECV in terms of ADR in RCTs and now supported by
this well-designed, large, real-world cohort analysis, the established benefits of
enhanced ADR in relation to reducing CRC mortality [1] and notwithstanding some remaining questions over advanced adenomas, ECV use across
screening programs should prove cost-effective. Further study is clearly needed in
this regard and is likely to be subject to jurisdiction with varying costs of ECV,
colonoscopy tariffs, and surveillance guidelines, as shown in other cost-effectiveness
studies for colonoscopy [13].
