Comment on “Combined use of tranexamic acid and rivaroxaban in posterior lumbar interbody fusion safely reduces blood loss and transfusion rates without increasing the risk of thrombosis-a prospective, stratified, randomized, controlled trial”

Abstract

Dear Editor: With much interest, we read the article by Zhang et al. [1] publ ished in October 2020 in the In ternat ional Orthopaedics. The authors performed a randomized controlled study and concluded that the combined application of tranexamic acid and rivaroxaban significantly reduced the amount of blood loss and the transfusion rate during posterior lumbar interbody fusion surgery and avoided an increase in the probability of thrombosis and the occurrence of epidural haematoma. At the outset, we would like to congratulate the authors for writing an informative article with novelty. Nevertheless, we have several suggestions and queries that we would like to communicate with the authors. Regarding the study design, we believe that there are lots of confounding factors. The study is single blinded and has not accounted for observer bias. The study included 599 cases, which were provided by eight hospitals. Different surgeons with their preferred technique did the surgery which is bound to introduce a high variation. A stratified analysis of results of each surgeon would have been better. Moreover, different surgeons may have different treatment of some details, such as the use of anticoagulants. However, post-operative anticoagulation regimens adopted by these surgeons were not mentioned, which would have a certain impact on the postoperative blood loss and even blood transfusion rate. We sincerely hope that the authors can provide these details for the present study. Another concern is the comparison between group C and group D in the results. The pre-operative Hb of group C and group D were 135.06 g/L and 138 g/L, respectively (P = 0.069); the Hb in post-operative day 3 of group C and group D were 109.54 g/L and 114.32 g/L, respectively (P = 0.025); and the Hb in post-operative day five of group C and group D were 114.75 g/L and 119.52 g/L, respectively (P = 0.044). The approximate statistical difference of Hb before surgery will affect the accuracy of Hb after surgery. Therefore, we doubt the significant statistical differences of post-operative Hb between group C and group D. Finally, we would welcome some comments by the authors as this would help to further support the findings of this important clinical trial. To reach a definitive conclusion, further high-quality prospective cohort studies based on larger sample sizes are still needed.