S3053 Effect of Small Bowel Transit Time on Diagnostic Yield in Small Bowel Capsule Endoscopy

Introduction: Small bowel capsule endoscopy (SBCE) is considered to be a first line diagnostic modality for evaluation of suspected small bowel bleeding after nondiagnostic upper endoscopy and colonoscopy. Several factors have been found to influence diagnostic yield. We investigated the influence of small bowel transit time (SBTT) on diagnostic yield in order to determine the predictive ability and optimum cutoff. Methods: We performed a retrospective cohort study of all SBCE in adults at an academic center from July 2015 through August 2022. We collected data on patient demographics and findings of SBCE. Unpaired t-tests, logistic regression, and receiver operating characteristic curve (ROC) analyses were carried out. The predictive ability was summarized with the area under the curve (AUC). Results: A total of 513 unique SBCE patients in whom the capsule reached the cecum were included in the study. There were 303 females (59.1%) and 365 Hispanic (71.2%) patients with a mean age of 59.9 years and body mass index of 29.9 kg/m2. Setting was outpatient in 263 (51.3%). The most common indications were obscure iron deficiency anemia (54.8%) and gastrointestinal bleed (39.2%), with a diagnostic yield of 203 (39.6%). The most common significant findings were angioectasia (17.2%), ulcer/erosion (12.9%), inflammation (11.5%), blood (6.2%), and active bleeding (3.9%). The average (SD) of SBTT was 259.3 (135.6, range: 10-847) min without any difference by patient demographics, except for age (58.8 vs 63.6, P = 0.001) between significant and non-significant SBCE findings. Longer SBTT (min) was associated with overall significant SBCE findings (275.8 vs 248.5, P = 0.026), and active bleeding (356.4 vs 255.4, P = 0.001). In adjusted analysis, SBTT (hr) was associated with higher odds of significant SBCE findings (OR, 1.08; 95%CI: 1.00, 1.17, P = 0.049). This correlation was stronger in patients found to have active bleeding (OR, 1.30; 95%CI: 1.10, 1.53, P = 0.002). The probability of finding significant lesions was only 0.5% at 35 min and 2.96% at 1 hour, indicating the minimum cutoff of SBTT should be at least 35 min-1 hr. An optimum cutoff of 4-5.5 hrs for SBTT yielded greater predictive ability for detecting significant lesions. Conclusion: In this retrospective cohort study of patients undergoing SBCE, we found that SBTT significantly affects diagnostic yield. At least 35 minutes was the minimum SBTT and 4 to 5.5 hours was the optimum time to detect significant findings.