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Updated: May 21, 2026

An R-Based Landscape Validation of a Competing Risk Model
Published on: September 16, 2022
Risk-adjusted cumulative sum (RA-CUSUM) method for real time monitoring of surgical units performance
Andrea Baldo1, Miho Akabane2, Jun Kawashima3
1Department of Surgery, The Ohio State University Wexner Medical Center and James Comprehensive Cancer Center, Columbus, OH, USA; Department of Surgery, Oncology and Gastroenterology, University of Padua, Padua, Italy.
Background:
This cross-sectional study evaluated risk-adjusted cumulative sum (RA-CUSUM), a tool for real-time monitoring of perioperative outcomes, in liver surgery across an international multicenter cohort.
Methods:
Patients undergoing curative-intent hepatectomy for hepatocellular carcinoma (31%), intrahepatic cholangiocarcinoma (29.7%), or colorectal liver metastases (39.3%) across 25 centers (2000-2023) were analyzed. RA-CUSUM curves were generated for operative time, intraoperative blood loss, major complications (Clavien-Dindo ≥ III), and length of stay (LOS). Mixed-effects models were used for overall curves and center-specific regressions for institutional analyses. Secondary outcomes included R1 resection and 1-year recurrence comparing the first 50 and subsequent cases at each center.
Results:
Among 5880 cases 38.2% were major hepatectomies, while 15.1% were minimally invasive. Median operative time was 240 min (IQR 150-356), median blood loss 300 mL (IQR 100-600), and median LOS 9 days (IQR 6-14). Major complications occurred in 35.1% of patients. RA-CUSUM curves demonstrated a biphasic pattern, with deterioration coinciding with the spread of minimally invasive surgery, and subsequent improvement. Center-level curves revealed marked heterogeneity. Secondary outcomes demonstrated no uniform early-period disadvantage.
Conclusions:
RA-CUSUM offers a real-time visualization of surgical performance and can guide quality review and support targeted quality-improvement initiatives in liver surgery units.
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