Thromboembolic and bleeding outcomes of extended duration low-intensity warfarin following elective total knee arthroplasty

Venous Thromboembolism Prophylaxis in Major Orthopedic Surgeries and Factor XIa Inhibitors

Venous thromboembolism (VTE), comprising pulmonary embolism (PE) and deep vein thrombosis (DVT), poses a significant risk during and after hospitalization, particularly for surgical patients. Among various patient groups, those undergoing major orthopedic surgeries are considered to have a higher susceptibility to PE and DVT. Major lower-extremity orthopedic procedures carry a higher risk of symptomatic VTE compared to most other surgeries, with an estimated incidence of ~4%. The greatest risk period occurs within the first 7-14 days following surgery. Major bleeding is also more prevalent in these surgeries compared to others, with rates estimated between 2% and 4%. For patients undergoing major lower-extremity orthopedic surgery who have a low bleeding risk, it is recommended to use pharmacological thromboprophylaxis with or without mechanical devices. The choice of the initial agent depends on the specific surgery and patient comorbidities. First-line options include low-molecular-weight heparins (LMWHs), direct oral anticoagulants, and aspirin. Second-line options consist of unfractionated heparin (UFH), fondaparinux, and warfarin. For most patients undergoing knee or hip arthroplasty, the initial agents recommended for the early perioperative period are LMWHs (enoxaparin or dalteparin) or direct oral anticoagulants (rivaroxaban or apixaban). In the case of hip fracture surgery, LMWH is recommended as the preferred agent for the entire duration of prophylaxis. However, emerging factor XI(a) inhibitors, as revealed by a recent meta-analysis, have shown a substantial decrease in the occurrence of VTE and bleeding events among patients undergoing major orthopedic surgery. This discovery poses a challenge to the existing paradigm of anticoagulant therapy in this specific patient population and indicates that factor XI(a) inhibitors hold great promise as a potential strategy to be taken into serious consideration.

Bleeding complications in patients on warfarin undergoing joint injection/aspiration: systematic review and meta-analysis

Steroid injections in joints are commonly administered for the management of inflammatory or degenerative conditions. There is substantial controversy as to whether to continue warfarin when undertaking joint injection or aspiration. To assess the rate of bleeding complications in patients on warfarin undergoing joint injection/aspiration. Systematic review and meta-analysis. A literature search of 3 online databases was conducted by 2 reviewers using the Cochrane methodology for systematic reviews. Eligibility criteria were any study that reported bleeding complication rates in adult patients on warfarin undergoing a joint injection/aspiration whilst taking warfarin anticoagulation. Studies reporting on less than 5 patients were excluded. Meta-analysis was conducted using a random effects model. The search of databases resulted in a total of 1547 articles. After screening, 8 articles were deemed suitable for inclusion in the analysis, involving 871 injection/aspiration procedures. There were only 5 reported cases of bleeding. On meta-analysis the estimated bleeding complication rate was 1.5% (95% CI 0.5-4.5%). This meta-analysis shows that it is safe to perform joint injection and aspiration in patients on warfarin without routine prior testing of INR. Level of evidence: Level 4.

Is Extended-Duration (Post-Hospital Discharge) Venous Thromboembolism Chemoprophylaxis Safe and Efficacious in High-Risk Surgery Patients? A Systematic Review

BACKGROUND

The risk of venous thromboembolism (VTE) persists beyond hospitalization in surgical patients, yet post-hospital discharge chemoprophylaxis regimens are not common. The purpose of this study is to systematically review the literature regarding extended-duration (post-hospital discharge) venous thromboembolism chemoprophylaxis and to determine whether it is warranted in high-risk surgical patients, as determined by its safety and efficacy.

METHOD

We searched four online databases for articles evaluating extended-duration (post-hospital discharge) VTE chemoprophylaxis regimens in surgical patients between the years January 2000 and February 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used. GRADE methodology and the Cochrane Risk of Bias Assessment Tool for Randomized Controlled Trials were used to grade the quality of evidence and assess risk of bias.

RESULTS

Nineteen studies with 10,544 patients were analyzed. The duration for extended-duration VTE chemoprophylaxis ranged from 7 to 42 days. In our study cohort, high-risk patients not prescribed extended-duration VTE chemoprophylaxis had a mean VTE incidence rate of 12.23%, while patients receiving 28-30 days of chemoprophylaxis had a mean VTE incidence rate of 4.37% (p = 0.006). The risk of bleeding events did not correlate with the duration of chemoprophylaxis.

CONCLUSION

Extended-duration VTE chemoprophylaxis in high-risk surgical patients decreased the incidence of thrombotic complications without increasing the risk of bleeding events. Further research is needed to establish guidelines for the optimal duration of VTE chemoprophylaxis in high-risk surgical patients.

LEVEL OF EVIDENCE

III.

Providers' utilization and perceptions of warfarin dosing algorithms

INTRODUCTION

Warfarin dosing algorithms have proven beneficial in increasing time within therapeutic range (TTR) and decreasing adverse events associated with out-of-range international normalized ratios (INRs). Despite widespread availability, providers' utilization and perceptions of warfarin algorithms in real-world practice are unclear. Identifying perceptions and barriers to algorithm use may help attempts to improve warfarin therapy management.

METHODS

Anticoagulation providers' utilization and perceptions of warfarin dosing algorithms were assessed via a nationwide electronic survey.

RESULTS

Of the 246 providers who completed the survey, 82% were pharmacists, and 69% had over five years' experience dosing warfarin. Warfarin dosing algorithms were deemed beneficial by 84% of respondents and 72% currently use a warfarin dosing algorithm in their practice at least occasionally. Pharmacists were least likely of anticoagulation providers to use algorithms, although this was not statistically significant (p = 0.12). Algorithm utilization also decreased as years of warfarin dosing experience increased, with the highest rate of usage noted in the first year of dosing warfarin. The most common reason providers gave for discontinuing algorithm use was that they no longer felt it was needed. In this study, clinic patient volume did not appear to be associated with algorithm utilization.

CONCLUSION

Warfarin dosing algorithms are frequently used among anticoagulation providers, especially those new to dosing warfarin, but use is frequently not sustained over the long-term. Education on the continued benefits of warfarin dosing algorithms could increase long-term utilization, potentially improving patient outcomes.

Venous Thromboembolism Prophylaxis After TKA: Aspirin, Warfarin, Enoxaparin, or Factor Xa Inhibitors?

BACKGROUND

There is considerable debate regarding the ideal agent for venous thromboembolism (VTE) prophylaxis after TKA. Numerous studies and meta-analyses have yet to provide a clear answer and often omit one or more of the commonly used agents such as aspirin, warfarin, enoxaparin, and factor Xa inhibitors.

QUESTIONS/PURPOSES

Using a large database analysis, we asked: (1) What are the differences in VTE incidence in primary TKA after administration of aspirin, warfarin, enoxaparin, or factor Xa inhibitors? (2) What are the differences in bleeding risk among these four agents? (3) How has use of these agents changed with time?

METHODS

We queried a combined Humana and Medicare database between 2007 and Quarter 1 of 2016, and identified all primary TKAs performed using ICD-9 and Current Procedural Terminology codes. All patients who had any form of antiplatelet or anticoagulation prescribed within 1 year before TKA were excluded from our study cohort. We then identified patients who had either aspirin, warfarin, enoxaparin, or factor Xa inhibitors prescribed within 2 weeks of primary TKA. Each cohort was matched by age and sex. Elixhauser comorbidities and Charlson Comorbidity Index for each group were calculated. We identified 1016 patients with aspirin, and age- and sex-matched 6096 patients with enoxaparin, 6096 patients with warfarin, and 5080 patients with factor Xa inhibitors. Using ICD-9 codes, with the understanding that patients at greater risk may have had more-attentive surveillance, the incidence of postoperative deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding-related complications (bleeding requiring surgical intervention, hemorrhage, hematoma, hemarthrosis), postoperative anemia, and transfusion were identified at 2 weeks, 30 days, 6 weeks, and 90 days postoperatively. A four-way chi-squared test was used to determine statistical significance. Utilization was calculated using compound annual growth rate.

RESULTS

There was a difference in the incidence of DVT at 90 days (p < 0.01). Factor Xa inhibitors (2.9%) had the lowest incidence of DVT followed by aspirin (3.0%) and enoxaparin (3.5%), and warfarin (4.8%). There was a difference in the incidence of PE at 90 days (p < 0.01). Factor Xa inhibitors (0.9%) had the lowest incidence of PE followed by enoxaparin (1.1%), aspirin (1.2%), and warfarin (1.6%). There was a difference in the incidence of postoperative anemia at 90 days (p < 0.01). Aspirin (19%) had the lowest incidence of postoperative anemia followed by warfarin (22%), enoxaparin (23%), and factor Xa inhibitors (23%). There was a difference in the incidence of a blood transfusion at 90 days (p < 0.01). Aspirin (7%) had the lowest incidence of a blood transfusion followed by factor Xa inhibitors (9%), warfarin (12%), and enoxaparin (13%). There were no differences in bleeding-related complications (p = 0.81) between the groups. Aspirin use increased at a compound annual growth rate of 30%, enoxaparin at 3%, and factor Xa inhibitors at 43%, while warfarin use decreased at a compound annual growth rate of -3%.

CONCLUSIONS

Factor Xa inhibitors had the highest growth in utilization during our study period, followed by aspirin, when compared with enoxaparin and warfarin. When selected for the right patient, factor Xa inhibitors provided improved VTE prophylaxis compared with enoxaparin and warfarin, with a lower rate of blood transfusion. Aspirin provided comparable VTE prophylaxis compared with factor Xa inhibitors with improved VTE prophylaxis compared with enoxaparin and warfarin with the lowest risk of bleeding.

LEVEL OF EVIDENCE

Level III, therapeutic study.