Comparison of the effect of single vs dual antiplatelet agents on post-operative haemorrhage after renal transplantation: A systematic review and meta-analysis.Lee, T., et al.
Transplantation Reviews 2021; 35(1): 100594.
The aim of this systematic review was to compare the perioperative outcomes of patients receiving single versus dual antiplatelet therapy during kidney transplantation, focusing particularly on postoperative haemorrhage.
Electronic databases including Embase, Medline and Cochrane were searched. Two independent reviewers conducted the literature search. The risk of bias was assessed using the Newcastle-Ottawa scale.
6 studies were included in the review.
The primary outcomes were the incidence of postoperative haemorrhagic events and major adverse cardiac events. The secondary outcomes were the need for surgical intervention for haemorrhage, and graft survival and function.
This is a good quality systematic review of dual versus single antiplatelet therapy and the impact on post-operative haemorrhage in renal transplantation. A search was conducted in multiple databases and a good description of study exclusion is presented in the flow chart. Search and study selection was conducted in duplicate, but the data extraction was not. Another good indicator is that the authors attempted to address missing data by first contacting each study authors. Studies were assessed for risk of bias using a recognised method by two authors independently. Only 6 studies met the inclusion criteria, including a total of 130 recipients on dual and 781 on single antiplatelet therapy. Four of the studies were cohort studies and 2 were case-control series, so there is the potential for bias due to the lack of randomisation. Post-operative haemorrhage was defined by each of the studies individually, but this did not result in any statistical heterogeneity. Five studies were included in meta-analysis, and this showed that dual antiplatelet therapy was convincingly associated with a higher risk of haemorrhage (RR= 1.58, 95%CI: 1.19-2.09). It is unclear if this translated to a higher risk of re-operation as this is not clearly documented in the included studies, and not all had this as part of their definition of post-operative haemorrhage; most relied on the requirement for transfusion or drop in haemoglobin. All included studies tended towards the conclusion that dual antiplatelet therapy increased this risk. Post-operative cardiac events were only reported by 3 included studies. In two of the studies, it was clear that the dual antiplatelet group had a proven history of coronary events, indicating that they were a higher risk group for this event. No meta-analysis was performed for this outcome due to heterogeneity and this is reasonable. There was no clear evidence of increased risk of cardiac event comparing dual and single antiplatelet groups in these studies. Whilst this review has a number of good quality indicators, the included patient population is small in number and the studies are not high level. Many transplant centres do not list patients on dual anti-platelet agents for kidney transplant surgery for two key perceptions: the increased risk of post-operative haemorrhage, and the requirement for dual antiplatelet therapy may indicate a higher risk of cardiac event after surgery. This review does give good support for the first assertion, but contains insufficient data to support the second one. The discussion gives a good account of the limitations and reasons for this.