How can we reduce disagreement among guidelines for venous thromboembolism prevention?

Recommendations on thromboprophylaxis in major joint arthroplasty - many guidelines, little consensus?

Venous thromboembolic events remain a concern in total hip and knee arthroplasty. Consequently, several guidelines on thromboprophylaxis have been established. However, despite similarities in methodology for evaluation of evidence, discrepancies in guideline recommendations continue to exist. Furthermore, the results of older randomized clinical trials still have significant influence despite major improvements in perioperative care. In contrast, the results of recent large cohort studies with fewer thromboembolic events are mostly used only for background data. Here we outline some of the differences between the guidelines on thromboprophylaxis from the American College of Chest Physicians, the National Institute for Health and Care Excellence and the American Academy of Orthopedic Surgeons. We discuss differences in the methodology and focus of the guidelines potentially influencing the final recommendations. Future analyses are required, including data from modern care with early mobilization and short length of stay.

Aspirin for the Prophylaxis of Venous Thromboembolic Events in Orthopedic Surgery Patients: A Comparison of the AAOS and ACCP Guidelines with Review of the Evidence

BACKGROUND

The American Academy of Orthopaedic Surgeons (AAOS) and the American College of Chest Physicians (ACCP) have both developed evidence-based guidelines to prevent venous thromboembolism (VTE) in high-risk orthopedic surgery patients. Recent changes to these documents have brought them into agreement as to the inclusion of aspirin as an appropriate option for VTE prophylaxis in this patient population.

OBJECTIVE

To evaluate the appropriateness of aspirin to prevent VTE in high-risk orthopedic surgery patients.

DATA SOURCES

Guidelines published by the AAOS in 2011 and the ACCP in 2012 were compared regarding their recommendations on the use of aspirin for the prevention of VTE. A literature search was also conducted to identify clinical trials that evaluated the use of aspirin for the prevention of VTE in this patient population. Search terms included the MeSH terms venous thromboembolism; venous thrombosis; pulmonary embolism; aspirin; arthroplasty, replacement, knee; arthroplasty, replacement, hip; and hip fractures/surgery.

STUDY SELECTION AND DATA EXTRACTION

Any study that evaluated aspirin, even in combination with another method of prophylaxis (such as pneumatic compression devices), and had been published during or after 1985 was included.

DATA SYNTHESIS

Randomized controlled trials, meta-analyses, and other large pooled and retrospective reviews have failed to consistently arrive at similar conclusions regarding the efficacy and safety of aspirin as an option for VTE prophylaxis in patients undergoing total knee arthroplasty (TKA), total hip arthroplasty (THA), or hip fracture surgery (HFS). Disagreements in the appropriateness of surrogate markers for safety and efficacy have resulted in differing recommendations from the ACCP and AAOS. The primary argument lies in the appropriateness of deep vein thrombosis as a surrogate marker for more serious outcomes such as pulmonary emboli.

CONCLUSIONS

Recent changes to both the ACCP and AAOS guidelines are in agreement for those who choose to use aspirin for chemoprophylaxis of VTE. Current surgical care improvement project measures do not include aspirin as an appropriate sole option for the prevention of VTE, but in patients undergoing elective TKA or who have a contraindication to pharmacologic prophylaxis and undergo a THA or HFS, aspirin in conjunction with compression devices as part of a multimodal approach would meet these measures. Data do not support the hypothesis that aspirin is less likely to cause adverse bleeding events than more potent anticoagulants.

Mechanical and suboptimal pharmacologic prophylaxis and delayed mobilization but not morbid obesity are associated with venous thromboembolism after total knee arthroplasty: a case-control study

BACKGROUND

The FDA-approved dose of low-molecular-weight heparin (LMWH) may not provide adequate thromboprophylaxis in morbidly obese patients after total knee arthroplasty (TKA). Suboptimal dosing, delayed initiation, and overreliance on mechanical methods may also limit the effectiveness of thromboprophylaxis.

OBJECTIVE

We explored the associations between the type of thromboprophylaxis, obesity, time of mobilization, and undergoing bilateral TKA on development of symptomatic venous thromboembolism (VTE) after TKA.

DESIGN/SETTING/PATIENTS

This was a case-control study of patients undergoing TKA in 15 teaching hospitals between October 2008 and March 2010. Cases were screened using the Agency for Healthcare Research and Quality's Patient Safety Indicator 12 and had objectively documented acute VTE within 9 days of surgery; controls were randomly selected from the same hospital. Multivariable logistic regression was used to analyze risk factors for postoperative VTE, adjusted for age and gender.

RESULTS

Among 130 cases with and 463 controls without acute VTE, body mass index (BMI) ranged from 17 to 61 (median = 34). Thromboprophylaxis was LMWH in 284 (48%), warfarin in 189 (32%), both in 55 (10%), and mechanical prophylaxis alone in 120 (20%). Overall, 77% ambulated on day 1 or 2 after surgery. Factors significantly associated with VTE were bilateral simultaneous TKA (odds ratio [OR] = 4.2; 95% confidence interval [CI]: 1.9-9.1), receipt of FDA-approved pharmacological prophylaxis (OR = 0.5; 95% CI: 0.3-0.8), and ambulation by postoperative day 2 (OR = 0.3; 95% CI: 0.1-0.9). Obesity was neither a significant confounder nor a modifier of these effects.

CONCLUSIONS

Severe obesity was not a significant independent predictor for VTE and did not modify the beneficial effect of FDA-approved pharmacological thromboprophylaxis. Bilateral TKA and failure to ambulate by the second day after surgery were significant risk factors.