Abstract
INTRODUCTION
We examined whether the introduction of an oral factor Xa inhibitor, increased total blood loss in patients undergoing primary total knee arthroplasty surgery.
METHODS
Two groups were studied. The intervention group were prescribed a factor Xa inhibitor 6-10 hours post-surgery, and the control group were prescribed low molecular weight heparin (LMWH) 6-10 hours post-surgery. All other factors were kept constant.
Pre- and post-operative haemoglobin levels (post-operative on day 2) were recorded. Any requirement for transfusion was also documented. Actual drop in haemoglobin levels was compared between the two groups.
RESULTS
43 patients were prescribed a factor Xa inhibitor and 37 patients LMWH thromboprophylaxis. Baseline pre-operative haemoglobin were comparable (p=0.91; 13.2 vs 13.2g/dL), however, post-operative blood loss was significantly increased in the factor Xa inhibitor group (p=<0.0001; 3.4 vs 2.6g/dL).
More patients required transfusion in the factor Xa inhibitor group (0.07% vs 0.03%).
Blood loss was significantly increased in the intervention group in patients who were not on anti-platelet medication, when compared with those on concurrent anti-platelet therapy (p=<0.001).
CONCLUSIONS
Oral factor Xa inhibitors significantly increase post-operative blood loss in total knee arthroplasty surgery when compared with LMWH. There is a subsequent increased requirement for blood transfusion and the potential complications related to bleeding and transfusion. These factors must be considered and balanced with the ease of oral anticoagulation when introducing these newer agents in total knee arthroplasty patients.
The anticoagulatory effects of oral factor Xa inhibitors are most pronounced in patients not on concurrent anti-platelet therapy.
