Supplementary Material for: Transfusion risk in open, laparoscopic and robotic-assisted surgery: A Propensity Score Matched Case-Control Study Across Surgical Disciplines

Introduction: Robotic-assisted surgery is increasingly performed in various surgical disciplines demonstrating improved oncological and functional outcomes compared to conventional surgery.
Problem/objective: Unclear is how robotic-assisted surgery affects perioperative anemia and the need for blood products.
Methods: In this case-control study 15,009 matched patient pairs undergoing urological, visceral or thoracic surgery were included. Pairwise comparisons between robotic-assisted surgery, laparoscopic surgery and open surgery were performed with propensity score matching.
Main results and conclusions: Robotic-assisted surgery compared to open surgery was associated with a risk reduction of allogeneic red blood cell transfusion by RR 0.32 (95% CI 0.27-0.37) and a limited reduction of perioperative hemoglobin (Perioperative hemoglobin difference of 0.40 g/dl, 95% CI 0.31-0.49). Robotic-assisted surgery was associated with a shorter length of hospital stay by 4.29 days (95% CI 3.74-4.84). Compared to laparoscopic surgery, robotic-assisted surgery had no significant effect on red blood cell transfusions (RR 0.94, 95% CI 0.75-1.18), perioperative hemoglobin (0.27 g/dl, 95% CI 0.16-0.38), or length of hospital stay 0.53 days (95% CI -0.14- 1.19).
Implications: Robotic-assisted and laparoscopic procedures are associated with reduced blood transfusions compared to open surgery and, thus the advancement of minimally-invasive procedures constitutes an important measure to improve patient outcomes.

引言：机器人辅助手术（robotic-assisted surgery）目前在各外科领域的应用日益广泛，相较传统手术，其展现出更优的肿瘤学与功能学预后效果。
问题与研究目标：目前尚不明确机器人辅助手术对围手术期贫血（perioperative anemia）以及血液制品（blood products）输注需求的影响。
研究方法：本病例对照研究（case-control study）纳入了15009对匹配患者，这些患者均接受泌尿、内脏或胸外科手术。研究采用倾向得分匹配（propensity score matching）法，对机器人辅助手术、腹腔镜手术与开放手术进行两两比较。
主要结果与结论：相较于开放手术，机器人辅助手术可使异体红细胞输注（allogeneic red blood cell transfusion）风险降低相对风险（Relative Risk，RR）0.32（95%置信区间（95% Confidence Interval，CI）：0.27~0.37），同时可小幅降低围手术期血红蛋白（hemoglobin）水平（围手术期血红蛋白差值为0.40g/dl，95%CI：0.31~0.49）；此外，机器人辅助手术可使患者住院时长（length of hospital stay）缩短4.29天（95%CI：3.74~4.84）。与腹腔镜手术相比，机器人辅助手术对红细胞输注（RR 0.94，95%CI：0.75~1.18）、围手术期血红蛋白（差值0.27g/dl，95%CI：0.16~0.38）及住院时长（0.53天，95%CI：-0.14~1.19）均无显著影响。
研究启示：相较于开放手术，机器人辅助手术与腹腔镜手术均可减少血液输注，因此微创手术（minimally-invasive procedures）的推广是改善患者预后的重要举措。