COSTS ANALYSIS OF ROBOTIC RECTAL RESECTION WITH TME: A COMPARISON BETWEEN THE DA VINCI SI AND XI

Background While several studies have been published regarding clinical and surgical benefits of robot-assisted colorectal surgery since the da Vinci Surgical System was introduced, to date few studies have reported a structured cost analysis, and none have analyzed the possible differences in costs between da Vinci Si and new da Vinci Xi. The aim of this study is to compare surgical parameters and costs of robotic surgery in rectal cancer with the use of da Vinci Si and Xi surgical system. Methods From April 2010 to April 2017, 90 robotic rectal resections were performed at our Institute with the da Vinci Si (Si-RobTME), or with the da Vinci Xi (Xi-RobTME). Based on CUSUM analysis, two comparable groups of 40 consecutive Si-RobTME and 40 consecutive Xi-RobTME were identified, and data of the prospectively collected database were retrospectively compared. Costs of the two procedures were collected and analyzed against the device specific robotic learning curve. Results The CUSUM learning curves of the two groups were identical, and were divided into two phases: Si1 and Xi1: cases 1–19; Si2 and Xi2: cases 20–40. No differences in the preoperative data, surgical procedure and pathological data were documented. A hybrid laparoscopic/robotic approach was used in 17 cases (42.5%) in the Si-RobTME group, in contrast to the full robotic approach used in all cases of Xi-RobTME group (p<0.001). Overall median operative time (OT) was significantly lower in Xi-RobTME than in Si-RobTME (275 vs 312.5 min, p = 0.021). A statistically significant change in OT by phase of robotic experience was detected (p <0.001), and median OT of phase Xi2 was lower than phase Si2 (265 vs 290 min, p=0.052) with a reduction of personnel costs (1151.6 vs 1260.2, p=0.052). Statistically significant reductions in overall variable costs were found between robotic phases (p < 0.001), and resulted lower in the Xi2 phase respect to the Si2 phase (7983 vs 10231.9, p=0.009). A statistically significant reduction in consumable costs by robotic phase was detected (p<0.001), and consumable costs of the Xi2 phase were significant lower than Si2 phase (p<0.001). Discussion The similar learning curve for both groups were likely due to a ‘proficiency-gain effect’ related mainly to the use of a new robotic technology, and not to the surgical operation itself. In fact, facing the new technology the surgeon must deal with new trocar dispositions, robotic cart position, new functions (pointing, targeting, camera hopping, etc.), new docking system and robotic arms regulation. Nevertheless, we found a significant optimization of costs with surgeon’s experience, and shifting from the old to new technology as well. We found this result as mainly due to the shorter OT, personnel costs and to the reduction of the consumable costs because of the higher number of full robotic approach registered with the da Vinci Xi