Methods	Prospective, randomised controlled study was performed to determine the haematological and biochemical changes, and clinical safety of post-operative autotransfusion in patients undergoing elective, non-emergency spinal surgery. A random number table was used to assign patients in equal numbers to two groups. Method of allocation concealment was not described
Participants	50 patients undergoing elective spinal surgery were randomly assigned to one of two groups: Group 1 (Autotransfusion group): n=25; M//F=7//18; mean (sd) age = 52 (16) years Group 2 (Control group): n=25; M//F=12//13; mean (sd) age = 52 (17) years
Interventions	Group 1: Autotransfusion group had their post-operatively drained blood collected into a Solcotrans Orthopedic Plus system. The salvaged blood was considered for re-infusion. No anticoagulation was added to the Solcotrans system. The duration of drainage was limited to the first 5-hours of the post-operative period. At the end of this period, patients from the Solcotrans group whose drained blood volume was greater than 200mls had this blood re-infused. Group 2: Control group had their post-operatively drained blood collected into a Solcotrans Orthopedic Plus system but the salvaged blood was not considered for reinfusion.
Outcomes	Outcomes reported: amount of blood re-transfused from the cell saver, amount of allogeneic blood transfused, number of patients transfused allogeneic blood, haematological variables
Notes	Transfusion threshold: blood transfusion (allogeneic and/or autologous) was given if the haematocrit level was below 25% during the peri-operative period
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Method used to generate allocation sequences was adequate.
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear.
Blinding (performance bias and detection bias) All outcomes	High risk