Patients with higher fecal hemoglobin levels or a history of smoking were more likely to require conversion from colon capsule endoscopy to conventional colonoscopy or flexible sigmoidoscopy, according to a large prospective study conducted in the United Kingdom.
The study included 603 adults who underwent colon capsule endoscopy (CCE) for gastrointestinal symptoms or postpolypectomy surveillance. All had fecal hemoglobin (f-Hb) levels up to 100 µg/g, per NHS England criteria. Researchers evaluated pre- and intraprocedural factors associated with conversion to conventional endoscopy.
Overall, 54.1% of patients required follow-up endoscopy, primarily due to polyp detection. Colonoscopy accounted for 32.9% of these cases, while 21.2% underwent flexible sigmoidoscopy.
“Log f-Hb level (odds ratio [OR] = 1.48, 95% confidence interval [CI] = 1.18–1.86, P < .001) and current smoker (OR = 1.44, 95% CI = 1.01–2.11, P = .047) were found to be significantly associated with CCC in both univariate and multivariate analyses,” wrote the authors, led by Ian Io Lei of the Institute of Precision Diagnostics & Translational Medicine at the University Hospital of Coventry and Warwickshire.
CCE completion—defined as full capsule excretion before battery depletion and adequate bowel cleansing—was achieved in 71.4% of patients. Male sex was associated with higher excretion rates (OR = 2.22, 95% CI = 1.10–4.58, P = .024), though this finding did not reduce the overall conversion rate because men also had higher polyp detection rates.
Diabetes was independently associated with poor bowel preparation (OR = 0.40, 95% CI = 0.18–0.87, P = .022) which was consistent with prior evidence that linked diabetes to delayed gastrointestinal transit.
Alcohol use, smoking, and psychological conditions were significantly associated with higher polyp counts. Antidepressant use was linked to larger polyp size, while beta-blocker use was associated with smaller polyps. These findings were not interpreted as causal.
Incomplete procedures, often due to inadequate bowel preparation or incomplete transit, frequently led to conversion. Bowel prep was inadequate in 22.9% of cases. When this occurred, clinicians typically opted for conventional colonoscopy rather than repeating CCE, given the ability to irrigate and visualize the mucosa.
The researchers emphasized the role of patient selection in optimizing CCE. While f-Hb is widely used in triage, its predictive accuracy in this study was limited. The area under the curve for f-Hb alone was 0.59, though it improved to 0.62 after adjusting for smoking status and bowel prep quality.
These findings suggest that smokers and patients with elevated f-Hb may benefit from direct referral to colonoscopy. The authors propose that further research could support the development of a risk stratification score to guide CCE use.
The authors reported no competing interests.
Source: BMC Gastroenterology
