PTU-019 Methadone use is associated with the development of common bile duct dilatation among patients with hepatitis C: results of a retrospective cohort study

Abstract

Introduction Methadone is a synthetic opioid widely used in the treatment of opioid dependence. Opioids induce sphincter of Oddi spasm and increase common bile duct (CBD) pressures. A previous study has shown an association between maintenance methadone therapy (MMT) and asymptomatic CBD dilatation. We aimed to establish rates of CBD dilatation amongst hepatitis C patients on MMT at initial assessment and on longitudinal follow up, versus control group. Methods We identified chronic HCV patients attending liver clinics at our institution between January 2003 and August 2010 from Scottish HCV Database. Age, gender, use of methadone, prior cholecystectomy, liver enzymes, CBD dilatation (>8mm) identified on initial and follow up abdominal ultrasound scan (AUS) were recorded. Hospitalization data regarding hepatobiliary complications was obtained from Scottish Information Services Division. Statistical analysis was performed to compare those prescribed MMT, versus controls not on MMT. Results 580 patients were identified, 287 (49.5%) on MMT and 293 (50.5%) controls. Mean age (42.3 v 48.5, p=0.99) and gender (71.5% male v 69.2%, p= 0.53) were similar between two groups. CBD dilatation on initial AUS was significantly higher amongst the MMT group (42/287(14.6%) v 18/293 (6%), p=0.0008). Few patients in either group had identifiable cause of CBD dilatation at the time of initial AUS (7/42 (17%) v 5/18 (28%), p =0.32). None of remaining 35 patients on MMT with dilated CBD developed hepatobiliary complications or identifiable pathology over a mean follow up of 31 months. Of those with a normal initial CBD, 109/246 (44.3%) MMT patients and 113/274 (41.2%) controls underwent an interval scan. Over similar durations of follow up (37.3v 38.2 months, p=0.7), MMT was associated with a higher rate of CBD dilatation (15/109(13.8%) v 5/113(4.4%), p=0.01). An obstructive cause was found in all controls who developed CBD dilatation but infrequently found in the MMT group (4/15 v 5/5, p=0.008). No significant pathology was found in those with a normal alkaline phosphatase. Conclusion Our study confirms the association between MMT and presence of CBD dilatation. For the first time we have demonstrated an increased rate of de novo CBD dilatation amongst MMT users on longitudinal follow up. MMT is associated with high prevalence of CBD dilatation, and infrequently associated with significant pathology. No patient with normal ALP demonstrated significant pathology in our cohort. Further work is required to establish and validate algorithms to identify patients receiving MMT in whom further investigation can be safely omitted.