The epidemiology of VTE after major orthopaedic surgery is changing, and with that there is a move towards a more nuanced and individual approach to prevention.
Professor Susan Kahn, from the Jewish General Hospital and McGill University in Canada, told the ISTH Congress that hip and knee arthroplasty patients were well known to be at an increased risk of VTE.
However with improvements in surgical techniques and postoperative management, leading to shorter surgeries and faster mobilisation, the risk of VTE now appeared to be falling.
She told the Congress that most VTE in orthopaedic surgery patients occur after hospital discharge, which had provided the impetus for extended prophylaxis out to 35 days.
However there was recent evidence that a shorter duration of prophylaxis, in hospital only, was appropriate for fast-tracked TKA and THA patients whose length of stay was five days or less.
“Until now we’ve used a whole group approach, that is, surgery-specific risk guiding our decision making. Now it is a more individual approach.”
She said high-risk patients had to be identified however risk assessment models were lacking. Previous VTE, very high BMI and advanced age >85 years were some of the known risk factors.
Professor Kahn said 2018 European guidelines recommended aspirin as an option for VTE prevention in arthroplasty patients who were not at high VTE risk, or had a high bleeding risk or those in a fast-tracked program.
A draft American Society of Hematology (ASH) guideline, due to be finalised later this year, was also expected to include a conditional recommendation to use aspirin for prophylaxis.
Results from the EPCAT ll study, which Professor Kahn co-authored, had also shown aspirin was non-inferior to rivaroxaban in the prevention of symptomatic VTE after arthroplasty.
In the study of more than 3,000 patients, all patients received rivaroxaban for the first five days postoperatively, and then were randomised to continue on the DOAC or switch to aspirin.
It found VTE in 0.64% of patients on aspirin and 0.7-% of rivaroxaban patients. Rates of clinically important bleeding complications were less than 1.5% and did not differ significantly between the two groups.
However Professor Kahn said it was too earlier to extrapolate from the study and widely adopt hybrid DOAC/aspirin protocols.
She said more evidence was coming in the form of the PEPPER trial of 25,000 arthroplasty patients across 24 sites in the US.
Patients were being randomised to aspirin, rivaroxaban or warfarin for 30 days in addition to pneumatic compression while in hospital.
“While I think we are shifting to a more individualised approach to VTE prophylaxis for major orthopaedic surgery patients, it is still early and we are not quite there yet, due to a lack of validated ways to assess risk both for VTE and for bleeding after major orthopaedic surgery.”
Professor Kahn said VTE after knee arthroscopy and distal leg fractures were infrequent and there was a lack of data to support the use of prophylaxis in high VTE risk patients.
However, she said “…if a patient is judged to have a higher than average risk of VTE due to previous VTE or cancer etcetera, then the clinician should not be constrained by the lack of trials in this area and should offer prophylaxis to these patients, as it is likely to do more good than harm.”