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.