Supplementary Material for: Risk factors for premature exchange of percutaneous biliary drainage in benign and malignant biliary strictures - a retrospective single-center study

Introduction: Treating biliary obstruction remains a common clinical problem. Endoscopic retrograde cholangiopancreatography (ERCP) with stent insertion remains the gold standard. If ERCP fails, percutaneous transhepatic biliary drainage (PTBD) is one treatment option. Despite a high success rate, early- and late onset complications occur frequently ranging from 20-70%. With this study we aimed to provide further insights on possible risk factors for PTBD-related complications. Methods: All cases with PTBD placement at our institution over the past 13 years were retrospectively analyzed and median premature exchange rate (mPER) as well as procedural associated complications were determined. Results: A total of 976 PTBDs were inserted in 194 patients. In 853 cases (87%) only one PTBD was inserted. Most patients had a benign disease as an indication for the PTBD insertion (n=558 cases, 56.9%). A premature PTBD exchanged occurred in 246 cases (26%). The most common reason for a premature PTBD exchange or extraction was a dislocation (n=98/39.5%) followed by cholangitis in 70 cases (28.6%). A malignant indication (multivariate p=0.001 OR=1.69 95% CI=1.23-2.30), female sex (multivariate p<0.001 OR=2.21 95% CI=1.56-3.12) and a PTBD ≥14Fr (multivariate p<0.03 1.50 (1.04-2.11) were associated with a premature stent exchange in the mixed multivariate regression analysis. Conclusion: Premature exchanges occur frequently in patients treated with PTBD. Especially in patients with malignancy, other interventional bile drainage interventions should be discussed. In case PTBD is chosen, earlier exchange rates than twelve weeks should be considered