785 Real World Application of the “Prometheus IBD Sgi Diagnostic” as a Baseline Test at a Tertiary Care IBD Referral Center

Abstract

INTRODUCTION: Prometheus IBD sgi Diagnostic (SGI) is an Inflammatory Bowel Disease (IBD) advanced diagnostic test developed by Prometheus Laboratories. It employs a diagnostic algorithm combining serologic, genetic, and inflammatory markers to help with clinical decision making in determining the accuracy of a diagnosis of IBD in patients suspected to have the disease. Moreover, among those it identifies as having IBD, it also seeks to assist in distinguishing those with Crohn's vs. those with ulcerative colitis (UC). In this observational clinical decision making study, we sought to examine the real world application of the SGI at a single tertiary care IBD practice especially in correctly identifying those with Crohn's vs. those with UC. METHODS: We included all adult IBD patients seen at a single tertiary IBD center practice from 2014 to 2017 that had baseline SGI done and during care at the practice, had a diagnosis of IBD (Crohn's or UC) established. We calculated sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and area under the curve based on results of SGI at baseline visit and the eventual established diagnosis of UC or CD. RESULTS: Of a total of 275 patients, there were 96 (34.9%) male patients and 179 (65.1%) female patients. The median age of these patients was 45.8. There were a total of 201 patients with biopsy proven CD. Of these, 104 were identified as having CD based on the baseline SGI and 97 who were identified as not having CD. Based on these data, the sensitivity of the SGI for CD at the practice was 52%, specificity was 88%, PPV was 92%, NPV was 40.1%, diagnostic accuracy was 61.5%, and Area under ROC was 70%. There were 66 patients with biopsy proven UC. Of these, 44 were identified as having UC based on the baseline SGI and 22 were identified as not having UC. Based on these data, the sensitivity of the SGI for UC at the practice was 67%, specificity was 85%, PPV was 58%, NPV was 89%, accuracy was 80%, and Area under ROC was 76%. CONCLUSION: Based on the results of this study, we conclude that the SGI is not a robust initial test in identifying those with Crohn's or those with UC. However, in a cohort of IBD patients seen at a tertiary care IBD practice, it is reasonably specific and accurate when it comes to correctly confirming Crohn's and even more so UC in patients with a caveat that the results should be interpreted in the proper clinical context and with the backing of other clinical indicators.