Blood Transfusion Rates as a Primary Outcome Measure: The Use of Predetermined Triggers and Display of Clinical Indications in Providing Accurate Comparative Transfusion Rates: To the Editor

on the efficacy of saline-coupled bipolar sealing devices in simultaneous bilateral total knee arthroplasty (TKA). The use of bipolar sealing and conventional electrocautery was compared in 71 consecutive patients who underwent bilateral TKA. Unfortunately, it must be noted that there are discrepancies in the reported transfusion rates. It was stated in the results section of the abstract that patients treated with the bipolar sealer were 35% less likely to require a transfusion when compared with patients treated with conventional electrocautery. The same percentage (35%) was presented in the conclusion section of the article. In contrast, the authors state that in their discussion that the blood transfusion rates were 33% lower in the experimental bilateral group when compared with the control group. The results section of the article and Table 2 claim that 55% (16 of 29) of patients in the experimental cohort required a blood transfusion, while the rate was 83% (35 of 42) in the control group. Therefore, the difference in transfusion requirements between the two groups would be 28% and not the 35% or 33% stated elsewhere in the paper. The need for blood transfusion was determined in the study based upon clinical need as determined by the surgeon and medical co-management team. This included consideration of pertinent medical comorbidities (e.g., strong history of cardiac disease), clinical symptoms such as lethargy, and hemodynamic parameters such as tachy-cardia and/or hypotension refractory to initial fluid resuscitation. In general, patients without cardiac history were not transfused for a haemoglobin level greater than 8 g/dL. Fixed, predetermined transfusion triggers were not employed , allowing the need for transfusion to appear vague in nature. As stated as a limitation, the staff and surgeons were not blinded and therefore there was a possibility of bias in the decision making process but the authors state that the criteria for transfusing symptomatic patients was used consistently. It is interesting to note that patients who were treated with the bipolar sealing device when compared with patients in the control group had: matched demographics, similar preadmission haemoglobin level (13.5 g/dL vs. 13.3 g/dL), similar estimated blood loss (100 mL) and nonsig-nificant increased haemoglobin decline (4.2 g/dL vs. 4.8 g/dL), yet finished with the significantly less transfusion requirements. It is unclear why there should be a significant difference in transfusion rates when other parameters were similar. One potential explanation for this could be age. It is known that transfusion …