Factors influencing warfarin control in Australia and Singapore

Integrated analysis of clinical and genetic factors on the interindividual variation of warfarin anticoagulation efficacy in clinical practice

AIM

The anticoagulation effect of warfarin is usually evaluated by percentage of time in therapeutic range (PTTR), which is negatively correlated with the risk of warfarin adverse reactions. This study aimed to explore the effects of genetic and nongenetic factors on anticoagulation efficacy of warfarin during different therapeutic range.

METHODS

We conducted an observational retrospective study aiming at evaluating the impact of clinical and genetic factors on PTTR from initial to more than six months treatment. This analysis included patients with heart valve replace (HVR) surgery who underwent long-term or life-long time treatment with standard-dose warfarin for anticoagulation control in Second Xiangya Hospital. All patients were followed for at least 6 months. We genotyped single nucleotide polymorphisms in VKORC1 and CYP2C9 associated with altered warfarin dose requirements and tested their associations with PTTR.

RESULTS

A total of 629 patients with intact clinical data and available genotype data were enrolled in this study, and only 38.63% patients achieved good anticoagulation control (PTTR > 0.6). Clinical factors, including male gender, older age, overweight, AVR surgery and stroke history, were associated with higher PTTR. Patients with VKORC1 -1639AA genotype had significantly higher PTTR level compared with GA/GG genotype carriers only in the first month of treatment. Patients with CYP2C9*3 allele had higher PTTR compared with CYP2C9*1*1 carriers. Moreover, compared with VKORC1 -1639 AG/GG carriers, INR > 4 was more likely to be present in patients with AA genotype. The frequency of CYP2C9*1*3 in patients with INR > 4 was significantly higher than these without INR > 4.

CONCLUSION

We confirmed the relevant factors of warfarin anticoagulation control, including genetic factors (VKORC1 -1639G > A and CYP2C9*3 polymorphisms) and clinical factors (male gender, older age, overweight, AVR surgery and stroke history), which could be helpful to individualize warfarin dosage and improve warfarin anticoagulation control during different treatment period.

Internationalisation of the curriculum in health programs

Internationalisation is a broad term that has been used to encompass a range of activities including international student recruitment, student mobility and exchange, international teaching and research collaborations, institutional partnerships, and embedding international and/or intercultural perspectives within curricula.There are numerous drivers for institutions to develop an internationalisation strategy including building global reputation and influence, having a positive influence on communities, income generation, and helping their students gain a global perspective or develop intercultural competencies. Health students benefit from internationalisation activities as they will enter a workforce that increasingly engages with global diseases and works within multicultural societies.However, there are risks associated with internationalisation that stem from disjointed institutional decision making, power imbalances, and neo-colonial attitudes. There are also multiple barriers to effectively engaging in internationalisation including individual student circumstances, staff and institutional preparedness, and geopolitical factors.Within this broader context, internationalisation of the curriculum (IoC) is aimed at incorporating international, intercultural, and global dimensions into the curriculum, including consideration of content, teaching methods, learning outcomes, and how these are supported at a program and institutional level. This is a major undertaking requiring alignment of philosophy between teaching academics, senior university leadership, and the relevant professional body. Examples of IoC within health programs, and the significant challenges involved, are critically discussed in this paper, and strategies to overcome these challenges highlighted.Whilst recognising the challenges, this paper concludes that undertaking purposeful IoC is a critical step towards ensuring that the future health workforce is adequately prepared for the 21st Century environment.

Comparison of potential pharmacokinetic drug interactions in patients with atrial fibrillation and changing from warfarin to non-vitamin K oral anticoagulant therapy

There are now anticoagulant choices with proposed advantages of non-vitamin K oral anticoagulants (NOACs) over warfarin being less routine monitoring and less drug interactions. Interacting medication can impact the efficacy and safety of anticoagulant therapy with management remaining clinically challenging. There have been limited studies comparing the potential for pharmacokinetic (PK) drug interactions between different anticoagulants. Therefore, the aim of this study was to compare potential PK interactions in patients with atrial fibrillation (AF) changing from warfarin to NOAC therapy. A retrospective analysis was conducted of patients with AF enrolled in a dedicated warfarin program but exiting this program to commence a NOAC. Patient data was collected, and concurrent medications were utilised to identify potential PK drug interactions with both warfarin and the chosen NOAC therapy. Patients were grouped according to the number of medications with potential PK interactions and comparisons made between groups. Of the 712 eligible patients who ceased warfarin to commence a NOAC, most commenced either apixaban (45.9%) or rivaroxaban (41.9%). When comparing warfarin to NOACs, there were significant differences in the proportion of patients taking no medication with potential PK drug interactions (46.9% vs 62.8%, p < 0.0001), and taking one (35.2% vs 28.5%, p = 0.0067) and two (14.5% vs 7.3%, p < 0.0001) potentially PK interacting medications. This study found when patients with AF were switched from warfarin to a NOAC, the potential for PK drug interactions significantly reduced but remained around 40%. Identifying and managing potential PK drug interactions with NOACs remains a priority to optimise clinical benefit of these anticoagulants.

Proton pump inhibitors co-prescribed with warfarin reduce warfarin control as measured by time in therapeutic range

INTRODUCTION

Warfarin is an oral anticoagulant that requires ongoing monitoring with time in therapeutic range (TTR), a common measure of the quality of warfarin control and likelihood of adverse events including bleeds. Numerous factors can influence these warfarin outcomes including drug interactions. Proton pump inhibitors (PPIs) have been reported to interact with warfarin but there remain conflicting reports with regard to the impact on bleeds and limited data on TTR. Therefore, the aim of this study was to determine the effect of PPIs on warfarin control using TTR and bleeds as endpoints.

METHODS

Retrospective data were collected for patients managed by a warfarin management clinic in Queensland. Data collected included current medications, reported bleeds and INR results to calculate TTR. Patients were grouped as taking PPIs or not taking PPIs. Analysis of TTR and bleeds occurred for these groups both before and after exclusions of other medication reported to interact with warfarin.

RESULTS

Of the 4494 included patients, almost half (44.5%) were taking PPIs with esomeprazole most commonly (34.8%) prescribed. Patients taking PPIs had significantly reduced TTR compared with patients not taking PPIs both before (78.5 ± 9.7% vs 81.7 ± 10.2%, P < 0.0001) and after (84.4 ± 5.1% vs 89.4 ± 8.0%, P < 0.0001) excluding all other interacting medications with warfarin. Patients taking PPIs also had significantly higher incidence of minor bleeds compared with patients not taking PPIs (32.4% vs 26.1%, P = 0.0487).

DISCUSSION

Patients taking PPIs with warfarin had significantly lower TTRs and higher incidence of minor bleeds. This combination warrants additional caution and monitoring with warfarin control as measured by TTR potentially affected.

Comparison of two point of care whole blood coagulation analysis devices and conventional coagulation tests as a predicting tool of perioperative bleeding in adult cardiac surgery-a pilot prospective observational study in Japan

BACKGROUND

It is widely accepted that Point-of Care Test (PoCT) devices are useful in the detection of coagulopathies in situations of massive bleeding such as major cardiac surgery. These devices contribute to the reduction of blood transfusion. However, their implementation remains limited in Japan because of their cost and lack of health insurance support.

STUDY DESIGN AND METHODS

Conventional coagulation tests and thromboelastography (TEG)/Sonoclot values were measured in 50 consecutive cardiac surgery cases. Clinical background information such as operative procedures was obtained from electronic medical records, and the theoretical perioperative total blood loss was calculated by measuring the hemoglobin content and total red blood cell transfusion volume. The correlation between perioperative total blood loss and the measured laboratory values or clinical parameters was evaluated by a multivariate linear regression analysis. The risk factors of the total amount of platelet transfusion and postoperative drain bleeding volume were similarly evaluated.

RESULTS

No significant association between the estimated perioperative total blood loss (eTBL) and the laboratory measurements including conventional coagulation tests, TEG and Sonoclot was observed. On the other hand, postoperative drain bleeding volume was significantly associated with postoperative Sonoclot CR (p = 0.039) as well as preoperative use of oral anticoagulants and cell saver treated blood volume. Platelet transfusion amount was significantly associated with post-CBP PF and time to peak value of Sonoclot (p = 0.014 and 0.001, respectively).

CONCLUSION

Sonoclot measurements may be useful to estimate the risks of postoperative bleeding and platelet transfusion in cardiac surgeries in Japan.

Stroke Prevention in Atrial Fibrillation: Focus on Asian Patients

Atrial fibrillation (AF) is the most common arrhythmia conferring a fivefold increased risk of stroke. Stroke prevention is the cornerstone of management of patients with AF. Asians have a generally higher incidence of AF-related risks of stroke and bleeding (particularly intracranial bleeding), compared with non-Asians. Despite the well-documented efficacy and relative safety of oral anticoagulation for stroke prevention among Asians, the suboptimal use of oral anticoagulation remains common. The current narrative review aims to provide a summary of the available evidence on stroke prevention among patients with AF focused on the Asia region, regarding stroke and bleeding risk evaluation, the performance of oral anticoagulation, and current use of thromboprophylaxis.