Structured cost analysis of robotic TME resection for rectal cancer: a comparison between the da Vinci Si and Xi in a single surgeon’s experience

Background: Robotic-assisted surgery by the da Vinci Si appears to benefit rectal cancer surgery in selected patients, but still has some limitations, one of which is its high costs. Preliminary studies have indicated that the use of the new da Vinci Xi provides some added advantages, but their impact on cost is unknown. The aim of the present study is to compare surgical outcomes and costs of rectal cancer resection by the two platforms, in a single surgeon’s experience. Methods: From April 2010 to April 2017, 90 robotic rectal resections were performed, with either the da Vinci Si (Si-RobTME) or the da Vinci Xi (Xi-RobTME). Based on CUSUM analysis, two comparable groups of 40 consecutive Si-RobTME and 40 consecutive Xi-RobTME were obtained from the prospectively collected database and used for the present retrospective comparative study. Data costs were analysed based on the level of experience on the proficiency–gain curve (p–g curve) by the surgeon with each platform. Results: In both groups, two homogeneous phases of the p–g curve were identified: Si1 and Xi1: cases 1–19, Si2 and Xi2: cases 20–40. A significantly higher number of full RAS operations were achieved in the Xi-RobTME group (p < 0.001). A statistically significant reduction in operating time (OT) during Si2 and Xi2 phase was observed (p < 0.001), accompanied by reduced overall variable costs (OVC), personnel costs (PC) and consumable costs (CC) (p < 0.001). All costs were lower in the Xi2 phase compared to Si2 phase: OT 265 versus 290 min (p = 0.052); OVC 7983 versus 10231.9 (p = 0.009); PC 1151.6 versus 1260.2 (p = 0.052), CC 3464.4 versus 3869.7 (p < 0.001). Conclusions: Our experience confirms a significant reduction of costs with increasing surgeon’s experience with both platforms. However, the economic gain was higher with the Xi with shorter OT, reduced PC and CC, in addition to a significantly larger number of cases performed by the fully robotic approach.