Optimal Preoperative Biliary Drainage in Malignant Hilar Biliary Obstruction: A Multicenter Observational Study Adjusted by IPTW

Background
For malignant hilar biliary obstruction (MHBO) requiring lobar resection, unilateral drainage (UD) is recommended to enhance future liver remnant (FLR) hypertrophy after portal vein embolization (PVE). However, UD's effect on cholangitis remains unclear, while bilateral drainage (BD) may potentially reduce cholangitis. We compared UD and BD in terms of cholangitis incidence and FLR hypertrophy, using inverse probability of treatment weighting (IPTW).
Methods
Between 2011 and 2023, 163 patients (Bismuth > II) underwent preoperative biliary drainage -UD (n=106) or BD (n=57)- at five institutions. Six covariates (Bismuth classification, disease, pre-drainage status, stent type, cholangitis at PBD, PVE status) were used for propensity-score generation and IPTW. We evaluated time to cholangitis and changes in %FLR (DeltaFLR) after PVE.
Results
Age, disease type, and Bismuth classification were similar between groups. PVE was performed in 46% (UD) vs. 70% (BD). Median waiting time was 35 vs. 48 days. Cholangitis occurred in 36% vs. 28%. After IPTW, time to cholangitis was 63 vs. 107 days. Because 80 days approximated the upper quartile of waiting, the 80-day cholangitis-free rates were 29.3% vs. 59.8%. Median DeltaFLR was +7.7% vs. +11.7%.
Conclusion
BD extended the cholangitis-free interval without adversely affecting FLR hypertrophy, suggesting it may be a more suitable drainage strategy than UD for resectable MHBO.