Reduction of serum bilirubin levels after endoscopic biliary drainage in patients with extrahepatic biliary obstruction and its significance

BACKGROUND Endoscopic retrograde cholangiopancreatography remains the primary modality for biliary decompression in extrahepatic biliary obstruction (EHBO). There are scarce data on the rate of fall in bilirubin after endoscopic biliary drainage (EBD) in EHBO. AIM To evaluate the rate and determinants of serum bilirubin decline after EBD in patients with EHBO and their impact on patient outcomes. METHODS This prospective observational study enrolled adults with EHBO and a serum total bilirubin level greater than 6 mg/dL who underwent endoscopic retrograde cholangiopancreatography from May 2023 to October 2024. Liver function tests were recorded at baseline and on days 1, 2, 7, and 15, and monthly thereafter. The primary outcome was the proportion of patients achieving a ≥ 50% decrease in bilirubin by day 7. Secondary outcomes included time to bilirubin < 3 mg/dL, predictors of biochemical response, need for reintervention, and 3-month mortality. RESULTS Among 101 patients, 60.4% had malignant EHBO. Overall, 80.2% achieved ≥ 50% bilirubin reduction by day 7, and 70.3% achieved bilirubin < 3 mg/dL by day 15. Benign etiology [adjusted odds ratio (aOR): 4.30; P = 0.038] and younger age (aOR: 0.95; P = 0.032) independently predicted an early response (day 7). Baseline bilirubin (aOR: 0.79; P < 0.001) and alkaline phosphatase levels (aOR: 1.002; P = 0.043) predicted bilirubin < 3 mg/dL by day 15. Reintervention was required in 15.8%, and 3-month mortality was 14.8%, predominantly in malignant EHBO. Failure to achieve > 50% reduction in bilirubin by day 7 was an independent predictor of reintervention, while failure to achieve bilirubin < 3 mg/dL by day 15 and acute kidney injury were independent predictors of mortality. CONCLUSION Failure to achieve ≥ 50% fall by day 7 predicts reintervention, while inability to reach bilirubin < 3 mg/dL by day 15 predicts mortality. Bilirubin kinetics following EBD serve as reliable indicators of drainage adequacy and short-term prognosis in EHBO.