Preoperative Conversion Risk Score for Acute Calculous Cholecystitis: Does TG18 Add Value?

Area of Science:

• Surgical Oncology
• Gastroenterology
• Medical Decision Making

Background:

• The 2018 Tokyo Guidelines (TG18) are standard for acute calculous cholecystitis but lack predictive value for laparoscopic to open cholecystectomy conversion.
• Individualized preoperative risk assessment is crucial for surgical planning and patient outcomes.

Purpose of the Study:

• To develop and validate a practical preoperative model and point-based score for predicting conversion risk.
• To compare the predictive performance of the new score against TG18 alone.

Main Methods:

• A retrospective cohort study of 183 patients undergoing laparoscopic cholecystectomy for acute calculous cholecystitis.
• Multivariable Firth penalized logistic regression identified predictors: age, diabetes mellitus, WBC, LDH, and gallbladder wall thickness.
• A point-based conversion risk score was derived from the final model.

Main Results:

• Conversion occurred in 18.0% of patients.
• The developed clinical and hybrid models demonstrated high discrimination (AUC 0.927-0.931).
• The derived score showed good discrimination (AUC 0.893), outperforming TG18 (AUC 0.576) and not significantly improved by its addition.

Conclusions:

• A simple preoperative score using age, diabetes, WBC, LDH, and gallbladder wall thickness offers superior patient-level prediction for conversion risk.
• TG18 is more useful for interpreting within-grade heterogeneity than for global discrimination of conversion risk.