Heiss 1993.

Methods	Design: Randomised controlled trial. Setting: Germany.
Participants	N = 120 patients undergoing colorectal surgery. Intervention group = M/F = 30/28; mean age ± SD = 58.9 ± 10.2 years Control group = M/F=31/31; mean age ± SD = 60.5 ± 10.0 years Inclusion criteria: intention of curative tumour resection and eligibility for enrolment in an autologous blood donation programme (Hb concentration ≥12.5 g/dL). Exclusion criteria: Acute infections, aged 75 years and over, history of seizures, unstable coronary disease, severe morbidity, or a likelihood that the tumour could not be resected.
Interventions	PAD (n = 58) Control group (n = 62) Timing of autologous blood collection/retransfusion: patients were scheduled to deposit two units of blood 7 and 10 days before surgery. Each unit was separated and stored as RBC concentrate preserved in citrate‐phosphate‐dextrose‐adenine (CPDA‐1) and fresh frozen plasma. The RBC concentrates were buffy coat poor, but not leukocyte‐depleted. Before every donation, a complete blood cell count was performed, and if the Hb value was less than 11.0g/dL, a second unit was not obtained. The predeposited units were matched and made ready. Additionally, 2 units of standard allogeneic leukocyte‐poor RBC concentrates were routinely kept in reserve in the transfusion centre. If more blood was needed, allogeneic blood was used. Iron supplementation: Iron supplementation was given to the intervention group as ferrous sulphate 100 mg orally twice daily. Transfusion thresholds: Transfusions were recommended at a haemoglobin concentration below 10.0 g/dL, based on measured blood loss. Other active intervention given to both arms: Decisions about the use of colloid and crystalloid fluids and blood transfusion were made by each patient's attending anaesthetist or surgeon.
Outcomes	Outcomes reported: Number of subjects exposed to allogeneic blood (n), allogeneic blood transfused (units), blood loss (mL), haemoglobin levels, postoperative infections (n), DTH responses.
Notes	Period of study: November 1987 and March 1991. Length of study: Participants were followed up for 3 months. A priori sample size: Not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	No information.
Allocation concealment?	Unclear risk	No information.
Blinding? All outcomes	Unclear risk	No information.
Intention‐to‐treat analysis?	Low risk	Data were analysed on an intention‐to‐treat basis.