Monday, February 26, 2018

Local Researchers Changing the Game Post Hip & Knee Replacement

Dr. David Anderson (Photo: Bruce Bottomley, courtesy Dalhousie)
Nova Scotia Health Authority (NSHA) and Dalhousie University researchers are changing the way we prevent venous thromboembolism (blood clots) after hip and knee replacement surgery. The EPCAT II Study (Extended Venous Thromboembolism Prophylaxis Comparing Rivaroxaban to Aspirin Following Total Hip and Knee Arthroplasty II) found that there was no significant differences between widely available, inexpensive Aspirin and current standard of care Rivaroxaban after total hip or total knee arthroplasty. The team was recently published in New England Journal of Medicine (NEJM).

"This large, randomized, double-blind trial is likely to be practice-changing, because the point estimates for the relative safety and efficacy of the two treatments are precise and the included patients represent a typical population undergoing joint-replacement surgery." says Dr. David Garcia who commented on the results in an NEJM Editorial.

Lead author Dr. David Anderson (Dalhousie University Dean of Medicine), Dr. Michael Dunbar (NSHA Orthopedic Surgeon, Researcher and QEII Foundation Endowed Chair in Arthroplasty Outcomes) and their research teams at NSHA completed an interdisciplinary study between orthopaedics and hematology. The study was a joint effort conducted at 14 other institutions across several provinces (NS, ON, QC, NB, MB) and many participating sites commended NSHA Hematology Research Manager Susan Pleasance and her team on their excellent study management. NSHA's Research Methods Unit (RMU) contributed with sample size calculation, analytic design and analysis of all results. They also contributed to data management activities of the study, including database consulting and design, data reporting, data cleaning and preparation for analysis.


This was an exceptional example of a large, interdisciplinary, inter provincial and multi-site cooperative research study.

The EPCAT II trial recruited patients from January 2013 through April 2016 and followed 3424 patients post knee and hip replacement in a multicentre, double blind, randomized control trial funded by CIHR.All enrolled patients had an initial 5 day course of Rivaroxaban, then randomized to continue on Rivaroxaban or switch to Aspirin for additional 9 days (knee-1620 patients) or 30 days (hip-1804 patients) and followed for 90 days post surgery. 

The primary effectiveness outcome was the rate of symptomatic venous thromboembolism. Results show that the rates were similar between the two drugs. The primary safety outcome was a major or clinically important bleeding event both of which were also similar between the two drugs.


The EPCAT II trial builds on the EPCAT I trial which suggested that extended prophylaxis with Aspirin after total hip replacement was as safe and effective as heparin to prevent venous thromboembolism after an initial 10-day postoperative course of heparin.

"Going forward, the very low rates of bleeding and thrombosis seen with the relatively inexpensive and user-friendly aspirin-based strategy probably mean that the EPCAT II trial has established a prophylaxis regimen against which all strategies to prevent venous thromboembolism after joint replacement will be compared." (Dr. David Garcia)


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