THE CURRENT DIAGNOSTIC ACCURACY AND INTER-OBSERVER AGREEMENT OF VISUAL IMPRESSION WITH DIGITAL SINGLE-OPERATOR CHOLANGIOSCOPY FOR THE DIAGNOSIS OF INDETERMINATE BILIARY STRICTURES

Aims Digital single-operator cholangioscopy (d-SOC) with cholangioscopic biopsy has shown promise in the evaluation of indeterminate biliary strictures (IBS). Some studies have suggested higher sensitivity for visual impression versus biopsies, however assessors were not blinded to previous investigations. We aimed to investigate the diagnostic accuracy and inter-observer agreement (IOA) of d-SOC in the visual appraisal of biliary strictures when blinded to history and previous results.

Methods A multicentre, international cohort study was performed. Cholangioscopic videos in patients with a known final diagnosis (based on pathology or at least 1 year of follow-up) were systematically scored. Anonymised videos were reviewed by 19 experts in 2 steps: 1: blinded for patients’ history and investigations and 2: unblinded. Cholangioscopic features were scored on a standard proforma.

Results Forty-four videos were reviewed (59% male, mean age 62 years) of 19 benign and 25 malignant strictures. The sensitivity and specificity for the diagnosis of malignancy was 74.1% and 47.1% (blinded) and 72.8% and 63% (unblinded). When primary sclerosing cholangitis (PSC) cases were excluded (n=11), sensitivity and specificity was 73.4% and 47.1% (blinded) and 75.1% and 61.1% (unblinded). The IOA for the presence of malignancy was fair for both the blinded (Fleiss’ kappa (F’k) 0.243) and unblinded assessment (F’k 0.325). For individual visual features, the IOA ranged from slight to moderate for both the blinded and unblinded assessment (F’k 0.058 - 0.401 versus F’k 0.030 - 0.450). There was moderate agreement for circumferential lesions (F’k 0.401) when blinded and for villous projections (F’k 0.450) when unblinded.

Conclusions This study shows low sensitivity and specificity for blinded and unblinded d-SOC video appraisal of IBS, with considerable interobserver variation. There remains a need to establish consensus opinion on the optical features of biliary strictures and their individual importance in the diagnosis of cholangiocarcinoma.