RCT retransfusion system vs. regular drain
D ISCUSSION In this study we have shown that patients treated with a postoperative retransfusion system (Bellovac) after TKA or THA had a significant reduction in allogeneic blood transfusions compared to controls treated with regular postoperative low-vacuum drains (Abdovac). This was shown by a significant absolute risk reduction of 13 percent (19% to 6%) in allogeneic blood transfusions (Table 4). Table 4. Risk reduction (%) of receiving at least one allogeneic blood transfusion*
Group Total group TKA THA
ARR 13 (19-6) 14 (16-2) 10 (21-11)
p Value 0.015 0.040 0.204
RRR 68% 88% 48%
NNT 7.7 7.1 10
* Significant differences between both groups are given. ARR = absolute risk reduction; RRR = relative risk reduction; NNT = numbers needed to treat
Nowadays most hospitals use restrictive transfusion triggers due to the awareness of risks and complications of allogeneic blood transfusions.1,2 This awareness and restrictive policy might be the most important factor in reducing allogeneic blood transfusions. The liberal policy with variable Hb transfusion triggers used in the past is a major confounding factor in retrospective studies or studies with historical cohorts. Owing to the many recent developments in blood management, new prospective randomised studies are needed. Therefore our prospective randomised clinical trial provides valuable information without the previously mentioned confounding factor. Patients in our study were transfused according to hospital transfusion policy, which is based on current Dutch consensus in blood management policy. Recently, the efficacy of a retransfusion system was shown by Str端mper and coworkers.11 Compared to a historical cohort, they reported a reduction from 35 to 22 percent for patients treated with a postoperative retransfusion system (Bellovac). This reduction was most pronounced in TKA (19% to 6%). We also noticed a significant reduction in allogeneic blood transfusions. Our reduction is in accordance with their findings; the overall results are not. The transfusion rate in our control group is even below the transfusion rate in the intervention group reported in the study of Str端mper and coworkers.11 The low
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