Ritter 1994.

Methods	A randomised, prospective study of participants undergoing primary total hip or total knee replacement over a six‐month period. Method of randomisation and allocation concealment were not described.
Participants	415 participants undergoing primary total hip or total knee replacement were randomly allocated to one of two groups: Drain group (Autotransfusion group): n = 215 No drain group (Control group): n = 200 Demographic data were not reported.
Interventions	Drain group: autotransfusion group received unwashed, filtered autologous blood processed by the Solcotrans autotransfusion system. No drain group: control group had no drainage system.
Outcomes	Outcomes reported: number of participants transfused allogeneic blood, amount of transfused blood, adverse events, knee flexion
Notes	Transfusion protocol: allogeneic blood was transfused if the haemoglobin level fell below 9.0g/dL. Prospective registration status: it is not clear whether the study was prospectively registered. Ethical approval: it is not clear whether the study received ethical approval from an ethics committee or institutional review board. Language: the study is published in English. Reason for awaiting classification status: there is a lack of detail regarding the intervention and comparison methods.