VTE Prevention: Is Aspirin Really That Good?
OrthoBuzz occasionally receives posts from guest bloggers. In response to a three recent studies, the following commentary comes from Jeffrey B. Stambough, MD.
Throughout the last decade, we’ve experienced a boom in anticoagulation options to help prevent venous thromboembolism (VTE) associated with orthopaedic procedures. The use of aggressive anticoagulation, such as warfarin and various heparin formulations, is being questioned, largely due to concerns about bleeding risks and wound complications. Along with the newer direct oral anticoagulants such as rivaroxaban, over-the-counter aspirin (ASA) is gaining prominence as an anticoagulant due to its high efficacy, low cost, convenience for patients, favorable side-effect profile, and cardioprotective attributes. Current guidelines include the use of all these thromboprophylactic agents, but three recent studies lend credence to using aspirin as the primary VTE prophylactic agent when performing total joint arthroplasty (TJA).
In a March 20, 2019 JBJS study analyzing >31,000 TJAs performed at a single institution over 17 years, Rondon et al. found a 3-fold lower 30-day and 2-fold lower 1-year mortality rate in patients receiving ASA (81mg or 325 mg twice daily), compared to those who received non-aspirin thromboprophylaxis (mainly warfarin). No mortality differences were noted between the two ASA dosing regimens. While investigating specific causes of death, the authors discovered that the primary cause of death in the non-ASA cohort was cardiac related at all time points.
A second study, from the April 3, 2019 JBJS, looked into the effects of 3 antithrombotic agents on symptomatic VTE rates and periprosthetic infections in high-risk patients undergoing primary or revision TJA. When compared to the two more potent agents (warfarin and low-molecular-weight heparin), ASA proved more effective at reducing pulmonary embolism (PE) and VTE rates in high-risk patients, and it was also associated with lower rates of periprosthetic joint infection when compared with warfarin. Thus, it seems that even in patients deemed to be higher risk for developing VTE, ASA may be a safe, effective option.
Lastly, Runner et al. gleaned VTE prophylaxis data from >22,000 TJA cases submitted by surgeons sitting for Part 2 of ABOS between 2014 and 2016. The findings, reported in the April 2019 issue of the Journal of Arthroplasty, showed similar trends to those seen in the two previously mentioned studies: Mild (distal or superficial deep vein thrombosis [DVT]), moderate (nonfatal PE, proximal DVT) and severe (fatal PE) VTE events, as well as death, were significantly less frequent in those who received ASA compared to more aggressive agents (heparin or one of its analogs, direct oral agents, or warfarin). Also, patients who received ASA with or without mechanical prophylaxis had significantly lower complication rates (95.5% vs. 93.0%, p<0.001).
One firmly held dogma in medicine is that patients who are at higher risk for VTE should be treated with stronger anticoagulation medications. However, these 3 studies support the idea that less aggressive anticoagulation medication (specifically, low-dose aspirin) may be the more effective and safer option for most patients. In our ongoing quest to improve patient outcomes and mitigate risk around the TJA episode, we should consider using aspirin for thromboprophylaxis unless there is an explicit contraindication in a specific patient.
However, we should also keep in mind that these three studies have the common limitations of all retrospective analyses. Recent randomized trials have shown aspirin to be “noninferior” to other anticoagulants for VTE prevention, and in less than 2 years, we should have even more definitive answers to this question from the randomized, multicenter PEPPER trial, with its estimated 25,000 participants.
Jeffrey B. Stambough, MD is an orthopaedic hip and knee surgeon, an assistant professor of orthopaedic surgery at University of Arkansas for Medical Sciences, and a member of the JBJS Social Media Advisory Board.
Preventing VTE in Below-the-Knee Surgery
Venous thromboembolism (VTE) following hip fractures and hip/knee arthroplasty—both deep vein thrombosis (DVT) and pulmonary embolism (PE)—has been relatively well studied. We therefore have a fairly clear understanding what the risks for DVT and PE are with no treatment as well as with modern preventive chemotherapeutic agents. However, such clarity on the need for and effectiveness of VTE prophylaxis is lacking for below-the-knee (BTK) orthopaedic procedures. This is largely due to the fact that such procedures have been deemed “low risk”—despite a dearth of supporting evidence for that assumption. In the March 20, 2019 issue of The Journal, Heijboer et al. used a sophisticated propensity score matching methodology to evaluate the rate of VTE in >10,000 BTK surgery patients at their tertiary care referral center.
The authors evaluated patients who underwent orthopaedic surgery distal to the proximal tibial articular surface, including foot/ankle procedures, open reduction of lower-leg fractures, and BTK amputations. They performed propensity score matching to compare 5,286 patients who received any type of chemotherapeutic prophylaxis with the same number who did not, across several key risk categories. The good news is that VTE prophylaxis effectively lowered the risk of symptomatic DVT or PE from 1.9% to 0.7% (odds ratio of 0.38, p <0.001).
Unfortunately (but not surprisingly), this effectiveness came at the price of increased systemic or local bleeding among patients using chemical VTE prophylaxis, with an incidence of 1.0% in the no-prophylaxis group and 2.2% in the prophylaxis group (odds ratio of 2.18, p <0.001). The authors did not assess the incidence of deep infection or hematoma formation, which often accompany increased local bleeding. The low overall incidence of VTE and bleeding did not allow for subgroup analysis according to location of surgery, and aspirin use was not controlled for in their study. In addition, Heijboer et al. used hospital coding data, and the accuracy of the database was not assessed.
The authors recommend that “anticoagulant prophylaxis be reserved only for patient groups who are deemed to be at high risk for VTE,” but we still don’t know precisely who is at high risk among BTK surgery patients. It is my hope that these findings will prompt large, prospective multicenter trials in the foot and ankle community to better determine which types of patients should be exposed to an increased risk of postoperative bleeding complications in order to achieve a clinically important decreased risk of VTE with chemical prophylaxis.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
PE Prevention—There’s an App for That
OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Matthew Herring, MD in response to a recent study in the Journal of Orthopaedic Trauma.
Pulmonary embolism (PE) is a potentially life-threatening complication among many orthopaedic trauma patients. PE can be a silent killer, with only about 30% of fatal PEs being detected before death. Chemical prophylaxis with “blood thinners” such as injectable enoxaparin is effective in mitigating the risk of PE, but in the poly-traumatized patient, its application is often contraindicated. In an effort to develop a more effective approach to PE prevention in the trauma population, Starr et al. built a tool to estimate the risk of PE early and effectively, and then developed a multidisciplinary protocol for deep vein thrombosis (DVT) prophylaxis. They present their preliminary experience with the risk-assessment tool and the new protocol in the February 2019 issue of the Journal of Orthopaedic Trauma.
The smart-phone app (ParkLandOrtho) to risk-stratify trauma patients in the ED is based on 7 easily captured variables that the authors’ prior work identified as statistically significant predictors for developing a PE. Patients who are identified as “high risk” are aggressively started on enoxaparin, with the first dose ideally given prior to ED discharge. If contraindications for chemical prophylaxis are present, enoxaparin is withheld for up to 24 hours after admission. After 24 hours, if the patient is still unable to receive enoxaparin, a removable inferior vena cava (IVC) filter is placed.
The authors performed a retrospective review of PE incidence among 368 consecutive orthopaedic trauma patients admitted to their hospital after this new protocol was implemented and compared it to PE incidence among a historic cohort of 420 similar consecutive patients admitted during the year prior to the protocol. The two groups were similar in age and injury severity. In the control group, 51 patients were retrospectively classified as high risk, and 9 patients (2.1%) developed symptomatic PEs, one of which was fatal. In the group managed under the new protocol, 40 patients were identified as high risk, and only 1 patient (0.27%) developed a nonfatal PE. The difference in incidence of PE between the two groups was statistically significant (P = 0.02).
This paper highlights two significant achievements in my opinion. First, I was excited to see the success of a smart-phone app to facilitate rapid risk assessment. This was a significant key to the success of the multidisciplinary PE protocol, which depends on buy-in and compliance. Second, this thoughtful, decisive, and team-based protocol for DVT/PE prophylaxis in an orthopaedic trauma setting seems to be making a meaningful impact on patient outcomes.
The authors report that they are currently designing a multicenter trial to prospectively validate their protocol. I eagerly await this and hope that their next step includes a ParklandOrtho app release for Android devices, as it is only available now for iPhone and Samsung users.
Matthew Herring, MD is a fellow in orthopaedic trauma at the University of California, San Francisco and a member of the JBJS Social Media Advisory Board.
Blood-Vessel Anomaly Boosts DVT Risk after ACL Reconstruction
The overall rate of symptomatic lower-extremity deep vein thrombosis (DVT) following arthroscopic ACL procedures is reported to be <0.3%, and guidelines from the American College of Chest Physicians recommend against DVT prophylaxis prior to arthroscopic knee surgery, unless a patient has risk factors for blood clots. But some patients are unknowingly at high risk for clots, as a case report by Ackerman et al. in the June 10, 2105 JBJS Case Connector shows.
A 45-year-old woman presented for arthroscopic ACL reconstruction in her left knee. Unbeknownst to her or her surgeons, the patient had asymptomatic May-Thurner syndrome—an anatomic variant of the iliac blood vessels in which the right common iliac artery crosses over the left common iliac vein, compressing the vein against the lumbar spine.
Nine days after ACL surgery, the patient showed up in the ED with pain and swelling in the operative leg. Ultrasound revealed an extensive DVT extending distally from the common femoral vein. Imaging of the chest and cardiac workups were negative for heart or lung thromboembolism.
A heparin drip was started, and a vascular surgeon ordered a left-leg venograph, which revealed a large clot extending from the origin of the left common iliac vein to the insertion site of the catheter in the popliteal vein. Severe stenosis of the left common iliac vein confirmed May-Thurner syndrome (see image below).
Treatment consisted of an infusion of tissue plasminogen activator (Alteplase) directly to the clot, continued intravenous heparin, and an angioplasty with stents to open the stenosed left common iliac vein. Mechanical thrombolysis and aspiration of a residual femoral vein thrombus was accomplished with a Trellis device.
Postoperatively the patient was transitioned to therapeutic warfarin for six months and instructed to wear compression stockings. She completed her ACL physical therapy protocol uneventfully, and one year after the ACL reconstruction, the knee graft was stable and there was no evidence of post-thrombotic syndrome.
The authors remind orthopaedists that May-Thurner syndrome, which is more common in women than men, should be suspected in the presence of an extensive iliofemoral DVT. They emphasize that multimodal and aggressive treatment, in consultation with a vascular specialist, should be initiated to bust the clot and reduce the risk of post-thrombotic syndrome. Post-clot, such patients should be maintained on warfarin for a minimum of six months, and patients with stents often require lifelong aspirin therapy.
JBJS Reviews Editor’s Choice–Achilles Tendon Ruptures
Among the topics that consistently stimulate debate among orthopaedic surgeons is the treatment of acute Achilles tendon rupture. The central question is typically, “Should this injury be treated operatively or nonoperatively?” In the April 2015 issue of JBJS Reviews, Guss et al. tackle this question.
The decision to treat acute Achilles tendon rupture has always been a trade-off between wound complications (associated with operative treatment) and the risk of rerupture (associated with both nonoperative and operative treatment but more commonly associated with nonoperative treatment). While the authors quote numerous reports, an important observation among all of the reports cited is that rehabilitation protocols for nonoperative treatment were not uniform across cohorts. Considering recent findings, the debate about operative vs. nonoperative intervention apparently has shifted from a focus on rerupture and infection to a focus on functional outcomes. Functional rehabilitation protocols have decreased the rerupture rate historically seen in association with the nonoperative treatment of these injuries. Operative treatment may provide some functional benefits, but recent studies suggest that many of these benefits are transient or subtle.
Guss at al. also point out that the rate of deep-vein thrombosis after Achilles tendon rupture may be higher than that observed in association with many other foot and ankle conditions. Indeed, the incidence of deep-vein thrombosis in patients with acute Achilles tendon rupture is possibly as high as one in three, but the vast majority of deep-vein thromboses are asymptomatic and are unlikely to be clinically relevant. Prophylactic anticoagulation should be considered for older patients with Achilles tendon rupture, including those managed nonoperatively, as well as for patients with other known risk factors.
In summary, recent reports have suggested that the use of functional rehabilitation in lieu of cast immobilization has, to a certain extent, reduced the higher rates of rerupture that historically have been associated with nonoperative treatment. Moreover, functional rehabilitation protocols are not associated with the wound complications that are inherently associated with operative repair. Operative repair may provide functional benefits, but reports have suggested that these benefits may be transient or incremental and limited to those patients who participate in more intense athletic endeavors. Indeed, more research with well-designed, randomized clinical trials is necessary to clarify the potential for incremental functional gain following operative repair as well as to identify those patients in whom nonoperative treatment is more likely to fail.
Thomas A. Einhorn, MD, Editor
Click here for another OrthoBuzz post about this JBJS Reviews article.
Functional Rehab Key to Nonoperative Management for Achilles Ruptures
The fact that 12 of the 16 AAOS clinical practice guidelines for treating Achilles tendon ruptures are supported by “weak” or “inconclusive” evidence makes the recent JBJS Reviews article by Guss et al. on this subject all the more welcome.
The most emphatic point made by these authors is that functional rehabilitation protocols with early motion (and an associated shift away from long-term post-injury immobilization) have made a dent in the re-rupture rates historically seen with nonoperative treatment of Achilles tendon injuries, the incidence of which has increased in recent decades. The authors emphasize, however, that the delicate balance between loading and unloading of a healing Achilles tendon remains a rehabilitative challenge, and they encourage further research to identify which patients are more or less likely to experience success with nonoperative management.
The authors note also that the focus of outcomes research of different management methods has shifted from rates of re-rupture and infection to more specific functional measures—and, in some cases, to direct and indirect cost measures. For example, Guss et al. cite one meta-analysis that found that operatively treated patients returned to work almost three weeks earlier than those treated nonoperatively.
The authors also observe that the rate of deep vein thrombosis after Achilles rupture seems to be higher than that seen in other foot/ankle conditions, but they add that the majority of those thrombotic events are “unlikely to be clinically important.” Still, Guss et al. conclude that “prophylactic anticoagulation should be considered for older patients with an Achilles tendon rupture, including those treated nonsurgically.”
Aspirin’s Effectiveness in VTE Prevention Varies by Procedure
“Deep vein thrombosis of the right leg” by James Heilman, MD – Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons
A recent meta-analysis of eight randomized trials (1,408 total patients) compared aspirin to anticoagulants such as warfarin and dabigatran for preventing venous thromboembolism (VTE) after hip and knee arthroplasty and hip-fracture repair. The analysis found that the overall prophylactic power of these two medical approaches was essentially equal following major lower-extremity surgery. However, the comparison, appearing in the Journal of Hospital Medicine, found a slightly higher (but statistically nonsignificant) risk of deep vein thrombosis (DVT) with aspirin following hip-fracture repair. Conversely, the risk of bleeding after hip-fracture surgery was lower with aspirin than with anticoagulants.
For additional insight into VTE prophylaxis, view the FREE recorded JBJS webinar “Preventing Arthroplasty-Associated Venous Thromboembolism.” Register here.
A Reminder about What Orthopaedic Surgeons Should Not Do
The Choosing Wisely campaign seeks to bring more awareness to tests and procedures that should be discussed between physicians and patients. The campaign was spearheaded by the ABIM Foundation, and the American Academy of Orthopaedic Surgeons (AAOS) partnered with the campaign to develop a list of the five things physicians and patients should question.
- Avoid performing routine post-operative deep vein thrombosis ultrasonography screening in patients who undergo elective hip or knee arthroplasty.
- Don’t use needle lavage to treat patients with symptomatic osteoarthritis of the knee for long-term relief.
- Don’t use glucosamine and chondroitin to treat patients with symptomatic osteoarthritis of the knee.
- Don’t use lateral wedge insoles to treat patients with symptomatic medial compartment osteoarthritis of the knee.
- Don’t use post-operative splinting of the wrist after carpal tunnel release for long-term relief.
The list was developed after review of approved clinical practice guidelines and included input from specialty society leaders.
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