Review for 10.1186/s12876-025-03828-9 (2025)

Title: Factors predicting conversion from Colon Capsule Endoscopy to Conventional Optical
Endoscopy - findings from the CESCAIL Study
Version: 4 Date: 07 Mar 2025
Reviewer:  Anwar Ashraf Abouelnasr
Reviewer's report:
Dear Authors, please address the following points below
-While the inclusion of retrospective data adds to the sample size, it may introduce some bias,
as the retrospective cohort may have different characteristics from the prospective cohort. A
discussion on how this might affect the results or a sensitivity analysis to account for potential
differences would strengthen the study.
-Although the NHS England CCE criteria are mentioned, there is no detailed description of
other inclusion or exclusion criteria, especially concerning comorbidities, medications, or prior
gastrointestinal history. These factors could potentially influence the success or failure of CCE
and conversion to CCC.
-The study is based in the UK and uses NHS England CCE criteria, which may limit the
generalizability of the findings to other healthcare systems or countries with different practices
and patient demographics. It would be beneficial to discuss how these results might apply
internationally or in different settings.
-Although the study briefly mentions intra-procedural factors (e.g., bowel preparation quality,
capsule excretion rates, pathology detection), these could be explored more comprehensively.
For example, factors such as procedure duration, technical difficulties, or patient tolerance
during the CCE could be further addressed to understand the full scope of potential predictors
for conversion.
-The study excludes patients with missing data (e.g., BMI, smoking history, alcohol
consumption), which may reduce the statistical power and introduce bias. A sensitivity analysis
to explore the impact of missing data or the use of imputation methods could help address this
limitation.
-The study uses a cutoff of f-Hb # 100 µg/g, but does not thoroughly discuss the potential
limitations or nuances of using this specific cutoff, especially given that FIT has known
limitations for detecting advanced polyps. A deeper exploration of the trade-offs of this cutoff
(and perhaps a comparison with other diagnostic markers) could provide valuable insights into
the study's design and findings.
-While the study focuses on clinical and procedural outcomes, patient satisfaction is briefly
mentioned but not a core outcome of the study. Since patient dissatisfaction was a key issue
identified in previous studies (e.g., the SCOTCAP study), it would be beneficial to explore this
aspect in greater depth, perhaps through surveys or other measures.
-While the discussion acknowledges that f-Hb has been identified as a predictor for CCC, it also
highlights the suboptimal predictive ability of the test (AuROC of 0.59). This may be considered
a limitation in its utility, especially since a threshold of # 100 µg/g was used in the cohort, which
may be more appropriate for low-risk populations. It would be beneficial to expand on potential
alternative diagnostic markers or thresholds that might yield better predictive accuracy for CCC.
-While the discussion provides a good rationale for why males may have a better capsule
excretion rate (e.g., differences in colonic length and pelvic structure), there is limited
exploration of the implications of gender differences for overall CCE performance. It
might be worth discussing whether the performance differences between genders affect the
generalizability of CCE or if specific interventions should be considered for females to improve
capsule excretion or video analysis.
-The study mentions a positive association between psychological conditions and polyp number,
though the interpretation is somewhat speculative. The assertion that the relationship might
reflect an anxious cohort under post-polypectomy surveillance is interesting, but it would benefit
from a more in-depth discussion of the potential mechanisms linking psychological conditions
with polyp formation or detection.
-Given that psychological conditions are frequently linked with chronic disease management,
further exploration of this aspect, including a better understanding of the mechanisms behind
this association, could enhance the findings.
-While the relationship between diabetes and inadequate bowel preparation is well supported,
other potential factors influencing bowel cleansing are not fully explored. For instance, the type
of bowel preparation used, patient adherence to instructions, or the timing of the procedure
relative to the bowel preparation could influence its quality.
-Since poor bowel preparation was a major factor in conversions to CCC, a more detailed
discussion of how to address this issue in practice could be valuable, such as recommendations
for better bowel prep protocols or patient education.
-The association between antidepressant use and larger polyp size is intriguing but not fully
explained. Although the discussion references studies suggesting a potential link between
depressive symptoms and CRC diagnoses, it would be helpful to explore the biological
mechanisms underlying these associations, as well as the potential impact of antidepressants
on polyp growth. Additionally, the claim that beta-blockers are linked to smaller polyp sizes
remains speculative, and further discussion on the possible mechanisms would be useful.