571 Diagnostic Accuracy of Narrow Band Imaging on Endoscopy in Detection of Duodenal Villous Atrophy Using Histopathology as a Gold Standard in Patients Presenting With Chronic Diarrhea

Abstract

INTRODUCTION: Celiac disease and tropical sprue are common causes of chronic diarrhea & duodenal villous atrophy (DVA). Narrow band imaging (NBI) is chromoendoscopic technique which facilitates detailed visualization of the mucosal surface & allows targeted biopsy and thus increases the diagnostic yield of the biopsy specimen. Hence, we aimed to determine the diagnostic accuracy of NBI in detection of DVA using histopathology as a gold standard in chronic diarrhea patients. METHODS: All patients with diarrhea for >4weeks were enrolled. Endoscopy was performed in all the patients to take duodenal biopsy and simultaneously NBI villous pattern was noted. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV), and diagnostic accuracy of NBI were calculated comparing histopathology. RESULTS: Baseline characteristics are shown in Table 1. NBI findings of total patients were finger shaped (normal villi), gyriform (partial villi atrophy) and flat surface (complete villous atrophy) mucosa as 22.6%, 59.7% and 17.7% respectively. NBI has sensitivity, specificity; PPV, NPV, and diagnostic accuracy were 84.9%, 45.2%, 82.3%, 50.0%, and 75% respectively for the detection of DVA as depicted in Table 2. CONCLUSION: This study showed 93 (75%) of participants had DVA in contrast to another study from Pakistan which revealed DVA in 49.8% of patients. This disparity is likely due to difference in study population. Our patients had normal villi, partial and complete villous atrophy in 31 (25%), 72 (58.1%) & 21 (16.9%) respectively with P value 0.001. Dutta AK et al. found that NBI has sensitivity 81-87%, specificity 93%, NPV 96% and PPV 68-77% to detect DVA. We found sensitivity 85%, specificity 45%, NPV 50% & PPV 82.3%. In our study specificity & NPV were lower than in others as we included mild villous atrophy while most of the studies had a greater proportion of patients with moderate to severe villous atrophy. We found that duration of diarrhea is associated with presence of villous atrophy, as disease duration of >5 months had sensitivity 92.1% and specificity 60% while 5 months had sensitivity & specificity 80% & 31.3% respectively. This association was not observed in previous studies. So we conclude NBI is a promising technique for assessment of duodenal mucosal details in patients with longstanding chronic diarrhea.