Diagnostic Values and Outcomes of Patency Capsule in Patients With Known or Suspected Intestinal Strictures

Abstract

Introduction: Video capsule endoscopy (VCE) is a standard tool for evaluating small bowel (SB) diseases. The most common complication of VCE is capsule retention. The most common cause of retention is SB stricture. Patency capsule (PC) is a self-dissolving capsule used to assess functional patency of the SB before VCE. However, data on the predictive values of PC are scarce. The purpose of our study was to evaluate the performance of PC in patients with known or suspected SB strictures and to identify predictive parameters of PC failure. Methods: At our institution, a tertiary academic center, we perform more than 1,000 VCEs each year. Inclusion criteria for this study included 306 patients with known or suspected SB strictures between 2009 and 2015 who had a PC study. Data on passage and failure of PC study and the clinical, imaging and laboratory parameters of these patients were collected. The patients with retained VCE (n=15) and/or surgery (n=4) were considered the reference standard for clinically significant luminal strictures. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, positive (PLR) and negative (NLR) likelihood ratios, and ROC curve with 95% confidence intervals (CI) were calculated. A p value < 0.05 was considered statistically significant. Results: Among the 306 patients, 43 patients (14%) failed to pass PC. Of the 43 patients, 21 (48.8%) had prior abdominal surgeries, 10 (23.3%) had chronic use of NSAIDs, and 8 (18.6%) had suspected or known Crohn's disease. 7 patients (16.3%) reported abdominal symptoms with PC failure, while the other 36 reported no symptoms. There were no statistical differences in the clinical parameters, including concurrent opioid use and diabetes, and laboratory parameters, including CRP and ESR, between the patients who passed (n=263) and who failed to pass PC (n=43). The sensitivity, specificity, PPV, NPV, PLR and NLR with their respective CIs for PC examination are detailed in Table 1. The AUC estimate of ROC curve was 0.51. Conclusion: While the sensitivity is low, the high specificity and NPV of the PC examination suggests that patients with suspected or known SB strictures can undergo VCE safely if PC has passed, thereby making it a useful test prior to VCE.Table 11