Cumulative Sum Analysis of the Operator Learning Curve for Robot-Assisted Mayo Clinic Level I–IV Inferior Vena Cava Thrombectomy Associated with Renal Carcinoma: A Study of 120 Cases at a Single Center

BACKGROUND: This study aimed to use cumulative sum analysis of the operator learning curve for robot-assisted Mayo Clinic level I–IV inferior vena cava (IVC) thrombectomy associated with renal carcinoma, and describes the development of an optimized operative procedure at a single center. MATERIAL/METHODS: A retrospective study included 120 patients with Mayo Clinic level I–IV IVC thrombus who underwent robotic surgery between 2013 and 2018. Points in the learning curve were identified using cumulative sum analysis, and their impact was assessed by multiple regression analysis. Perioperative indicators analyzed included operative time, estimated blood loss, early complications, and the 90-day progression rate. RESULTS: Cumulative sum analysis identified three phases in the learning curve of robot-assisted IVC thrombectomy. The median operative time decreased from 265 min (range, 212–401 min) to 207 min (range, 146–276 min) (p=0.003), the median estimated blood loss decreased from 775 ml (range, 413–1500 ml) to 300 ml (range, 163–813 ml) (p=0.006), and the early complication rate decreased from 52.5% to 15.0% (p<0.001). Multivariate analysis showed that for an initial 40 cases and a further 80 cases, the learning phase, the affected side, the Mayo Clinic level, and the surgical method were independent factors that affected operative time, estimated blood loss, and the rate of early complications. CONCLUSIONS: Experience from an initial 40 cases and a further 80 cases of Mayo Clinic level I–IV IVC thrombectomy associated with renal carcinoma were found to provide acceptable surgical and clinical outcomes.