Management of Outpatient Warfarin Therapy amid COVID-19 Pandemic: A Practical Guide

Role of Cytochrome P450 2C9 in COVID-19 Treatment: Current Status and Future Directions

The major human liver drug metabolising cytochrome P450 (CYP) enzymes are downregulated during inflammation and infectious disease state, especially during coronavirus disease 2019 (COVID-19) infection. The influx of proinflammatory cytokines, known as a 'cytokine storm', during severe COVID-19 leads to the downregulation of CYPs and triggers new cytokine release, which further dampens CYP expression. Impaired drug metabolism, along with the inevitable co-administration of drugs or 'combination therapy' in patients with COVID-19 with various comorbidities, could cause drug-drug interactions, thus worsening the disease condition. Genetic variability or polymorphism in CYP2C9 across different ethnicities could contribute to COVID-19 susceptibility. A number of drugs used in patients with COVID-19 are inducers or inhibitors of, or are metabolised by, CYP2C9, and co-administration might cause pharmacokinetic and pharmacodynamic interactions. It is also worth mentioning that some of the COVID-19 drug interactions are due to altered activity of other CYPs including CYP3A4. Isoniazid/rifampin for COVID-19 and tuberculosis co-infection; lopinavir/ritonavir and cobicistat/remdesivir combination therapy; or multi-drug therapy including ivermectin, azithromycin, montelukast and acetylsalicylic acid, known as TNR4 therapy, all improved recovery in patients with COVID-19. However, a combination of CYP2C9 inducers, inhibitors or both, and plausibly different CYP isoforms could lead to treatment failure, hepatotoxicity or serious side effects including thromboembolism or bleeding, as observed in the combined use of azithromycin/warfarin. Further, herbs that are CYP2C9 inducers and inhibitors, showed anti-COVID-19 properties, and in silico predictions postulated that phytochemical compounds could inhibit SARS-CoV-2 virus particles. COVID-19 vaccines elicit immune responses that activate cytokine release, which in turn suppresses CYP expression that could be the source of compromised CYP2C9 drug metabolism and the subsequent drug-drug interaction. Future studies are recommended to determine CYP regulation in COVID-19, while recognising the involvement of CYP2C9 and possibly utilising CYP2C9 as a target gene to tackle the ever-mutating SARS-CoV-2.

Cardiovascular implications of the COVID-19: Management of complications and drug safety concerns

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, has rapidly spread worldwide and has been infected more than 219 million individuals with 4.55 million deaths worldwide as of September 2021, causing a pandemic. Preexisting cardiovascular (CV) comorbidities such as hypertension, diabetes, and coronary artery disease seem to be associated with greater severity of infection, worse prognosis, and higher mortality. Moreover, COVID-19 can contribute to CV complications, including acute myocardial injury, arrhythmia, acute coronary syndrome, and venous thromboembolism, emphasizing the importance of precocious detection and implementation of optimal therapeutic strategies. This review provides an overview of evidence-based data of CV complications of COVID-19, focusing on their management strategies, as well as potential cardiac adverse effects and drug interactions, due to off-label and investigational drugs used for the treatment of COVID-19.

Proportion of Patients on Warfarin Therapy Who Are Eligible for Conversion to a Direct Oral Anticoagulant in the Setting of COVID-19

Background:

Warfarin, a commonly prescribed anticoagulant, requires frequent lab monitoring. Lab monitoring puts patients at risk of COVID-19 exposure and diverts medical resources away from health care systems. Direct oral anticoagulants (DOACs) do not require routine therapeutic monitoring and are indicated first line for nonvalvular atrial fibrillation (NVAF) stroke prevention and venous thromboembolism (VTE) prevention/treatment.

Objective:

The purpose of the study was to determine the proportion of patients who qualify for DOACs and assess for predictors of qualification.

Methods:

This cross-sectional study investigated patients on warfarin managed by Michigan Medicine Anticoagulation Service. Direct oral anticoagulant eligibility criteria were established using apixaban, dabigatran, and rivaroxaban package inserts. Patient eligibility was determined through chart review. The primary outcome was the proportion of patients who qualify for DOACs based on clinical factors. Predictors of DOAC qualification were assessed.

Results:

This study included 3205 patients and found 51.8% (n = 1661) of patients qualified for DOACs. Qualifying patients were older (71.9 vs 59.4 years, P < 0.0001) with a higher CHA₂DS₂ VASc (3.7 vs 3.4, P < 0.0007). The primary disqualifying factor was extreme weight, high and low. Accounting for a patient’s sex and referral source, age > 65 (odds ratio [OR] = 1.9, P < 0.0001) and NVAF indication (OR = 5.6, P < 0.0001) were significant predictors for DOAC qualification.

Conclusion and Relevance:

Approximately 52% of patients on warfarin were eligible for DOACs. This presents an opportunity to reduce patient exposure to health care settings and health care utilization in the setting of COVID-19. Increased costs of DOACs need to be assessed.

Warfarin anticoagulation management during the COVID-19 pandemic: The role of internet clinic and machine learning

Background: Patients who received warfarin require constant monitoring by hospital staff. However, social distancing and stay-at-home orders, which were universally adopted strategies to avoid the spread of COVID-19, led to unprecedented challenges. This study aimed to optimize warfarin treatment during the COVID-19 pandemic by determining the role of the Internet clinic and developing a machine learning (ML) model to predict anticoagulation quality.

Methods: This retrospective study enrolled patients who received warfarin treatment in the hospital anticoagulation clinic (HAC) and “Internet + Anticoagulation clinic” (IAC) of the Nanjing Drum Tower Hospital between January 2020 and September 2021. The primary outcome was the anticoagulation quality of patients, which was evaluated by both the time in therapeutic range (TTR) and international normalized ratio (INR) variability. Anticoagulation quality and incidence of adverse events were compared between HAC and IAC. Furthermore, five ML algorithms were used to develop the anticoagulation quality prediction model, and the SHAP method was introduced to rank the feature importance.

Results: Totally, 241 patients were included, comprising 145 patients in the HAC group and 96 patients in the IAC group. In the HAC group and IAC group, 73.1 and 69.8% (p = 0.576) of patients achieved good anticoagulation quality, with the average TTR being 79.9 ± 20.0% and 80.6 ± 21.1%, respectively. There was no significant difference in the incidence of adverse events between the two groups. Evaluating the five ML models using the test set, the accuracy of the XGBoost model was 0.767, and the area under the receiver operating characteristic curve was 0.808, which showed the best performance. The results of the SHAP method revealed that age, education, hypertension, aspirin, and amiodarone were the top five important features associated with poor anticoagulation quality.

Conclusion: The IAC contributed to a novel management method for patients who received warfarin during the COVID-19 pandemic, as effective as HAC and with a low risk of virus transmission. The XGBoost model could accurately select patients at a high risk of poor anticoagulation quality, who could benefit from active intervention.

Virtual Education for Patient Self-Testing for Warfarin Therapy Is Effective During the COVID-19 Pandemic

BACKGROUND

Prior to the COVID-19 pandemic, warfarin users were required to complete in-person training in order to participate in approved international normalized ratio (INR) patient self-testing (PST) programs. To minimize in-person contact during the pandemic, a federal waiver of the in-person training requirement allowed new patients to begin PST after completing virtual training. However, it was uncertain whether such patients achieved comparable levels of INR control to patients receiving in-person training.

METHODS

INR results for patients receiving virtual training upon PST commencement between April 1, 2020, and December 31, 2020, were compared to those of patients initiating PST with in-person training between April 1, 2019, and December 31, 2019. The primary outcome was the difference in warfarin time in therapeutic range (TTR) between the groups, with secondary outcomes including differences in the percentages of INR values within individually prescribed INR range and of critical INR values.

RESULTS

The records of 33,683 patients were included in the analysis (13,568 in the "In-Person" sample; 20,115 in the "Virtual" sample). Patients in the Virtual sample achieved a TTR of 66.78%, compared to the In-Person sample (64.19%; absolute difference 2.59; 95% confidence interval [CI] = 2.50-2.68, p < 0.001). The TTR values were also statistically significantly higher in all subgroups evaluated across categories of patient age, gender, geography, and indication. Similarly favorable results were achieved for INR values in range and critical values.

CONCLUSION

Virtual education for PST for warfarin therapy is effective and should continue to be an option for patients and providers throughout the pandemic, and possibly beyond.

Efficacy and safety of app-based remote warfarin management during COVID-19-related lockdown: a retrospective cohort study

This study aimed to explore the effectiveness, and safety of internet-based warfarin management during the pandemic. In this single-center retrospective cohort study, we compared the safety and efficacy of online warfarin management using a smartphone app (the Alfalfa app) versus conventional outpatient clinic management from January 1, 2020 to March 31, 2020. Patients in the online management group used the Alfalfa app to communicate coagulation test results and other relevant information to a doctor or clinical pharmacist, who then responded with the dose adjustment plan and the date of the next blood test. The outcomes examined were the time in therapeutic range (TTR), incidence of clinical events (i.e., bleeding events, thrombotic events, warfarin-related emergency department visits, and warfarin-related hospital admissions), and the distribution of international normalized ratio (INR) values. Data from 117 patients were analyzed in this study. TTR was significantly higher in the online group than in the offline group (61.0% vs. 39.6%, P < 0.01). Incidence of major bleeding events, thrombotic events, and warfarin-related hospital admissions were comparable between the online and offline groups. However, minor bleeds (5.3% vs. 28.3%, P < 0.01) and warfarin-related emergency department visits (1.8% vs. 23.3%, P = 0.02) were significantly fewer in the online group than in the offline group. The proportion of INR values in the therapeutic range (53.8% vs. 40.1%, P < 0.01) was significantly higher in the online group. Warfarin management using the Alfalfa app appears to be a safe and effective method for warfarin management when patients cannot physically visit hospitals for follow-up.

Performance of the microINR Point-of-Care System Used by Self-Testing Patients: A Multicenter Clinical Trial

Introduction  Anticoagulation monitoring is a major practical and clinical challenge. We assessed the performance of the microINR system in patient self-testing (PST). Methods  This study was performed at four US medical centers. After the training visit of warfarin anticoagulated patients ( n  = 117) on microINR system, PST was performed at home and in two visits to the medical centers. At the medical centers, both PST and healthcare professionals (HCPs) performed duplicate tests with the microINR System. A venous blood sample for the laboratory testing was also extracted. Accuracy and precision were assessed. Results  The comparison between microINR PST results and microINR HCP results revealed an equivalence with a slope of 1.00 (95% confidence interval [CI]: 1.00-1.00), and an intercept of 0.00 (95% CI: 0.00-0.00). When compared with the laboratory analyzer, microINR PST results also showed good correlation with a slope of 0.94 (95% CI: 0.86-1.04) and an intercept of 0.14 (95% CI: -0.09-0.34). Predicted bias values at international normalized ratio (INR) 2.0, 3.5, and 4.5 were 0% against HCP and ≤2.5% against the laboratory. Analytical agreement with both HCP and laboratory was 100% according to ISO17593 and 99.1 and 100% according to CLSI POCT14 with HCP and laboratory, respectively. Clinical agreement with HCP regarding 2.0-4.0 as INR therapeutic range was 98% (within range). The precision (coefficient of variation) of microINR system used by PST was comparable to HCP. Conclusion  The microINR results when used by self-testing patients show satisfactory concordance to both HCP results and laboratory analyzer. The microINR system is adequate for self-testing use.

Impact of Pregnancy-Related Venous Thromboembolism on Quality of Patients' Lives

Background: During pregnancy, the risk of venous thrombo-embolism (VTE) is increased at least five times compared with non-pregnant women of the same age, while the relative risk in the postpartum period can be as high as sixty times. The aim of the study was to explore the impact of pregnancy-related VTE on patients' mental, professional, social and personal life. Methods and Materials: Cross-sectional study at Jordan University Hospital's Obstetrics Department. Results: There were 112 women. Forty-six (41.1%) had a postpartum VTE. Twenty-eight of the patients (25%) had comorbidity. Eleven (9.9%) had a previous episode of VTE. Thirty-nine (35%) of the women reported three or more hospital visits over the past six months. Twenty-one (19.6%) of the women answered that their leg or chest pain has impeded their social activities. Anxiety/Depression was reported by 96.43% while Pain/Discomfort by 73.21%. A significant reduction of time spent on their work (correlation = 0.663, significant at <0.01) and accomplishing less work (correlation = 0.787, this was significant at <0.01) was found; 57.14% of patients indicated that VTE affecting their future pregnancies; 58.9% of patients were receiving anticoagulants with the most commonly used drug was aspirin. Twenty-four (36.4%) of the women were on multiple anticoagulant therapies. Twenty-five of the patients receiving medications do not monitor their medications and 20 patients said that monitoring the drug level was a bother to them. Conclusions: Pregnancy-related VTE had a significant adverse impact on physical, mental and professional life of women. It also had negative effects on future pregnancy plans.

Drive-through Anticoagulation Clinic During The COVID-19 Pandemic

An innovative approach to anticoagulation management during the COVID-19 pandemic was used at our center that allowed patients to stay in their vehicle while our anticoagulation advanced practice registered nurse obtained blood for point-of-care international normalized ratio (INR) testing while education and counseling were completed. A significant improvement in the median percentage of INR within the therapeutic range was observed among the patients who used the drive-through clinic. A small group of patients improved compliance to anticoagulation monitoring. Clinical care models, such as this clinic approach may improve patient compliance and adherence to anticoagulation beyond the pandemic needs.

Structural Changes of Sodium Warfarin in Tablets Affecting the Dissolution Profiles and Potential Safety of Generic Substitution

At present, the risk of generic substitutions in warfarin tablets is still being discussed. The aim of this study was to assess whether API interactions with commonly used excipients may affect the safety of generic replacement of warfarin sodium tablets. These interactions were observed during an accelerated stability study, and the effect of the warfarin solid phase (crystalline/amorphous form) as well as the API particle size distribution was studied. Commercial tablets and prepared tablets containing crystalline warfarin or amorphous warfarin were used. In addition, binary mixtures of warfarin with various excipients were prepared. The structural changes before and after the stability study were monitored by dissolution test in different media, solid-state NMR spectroscopy and Raman microscopy. During the stability study, the conversion of the sodium in warfarin to its acid form was demonstrated by some excipients (e.g., calcium phosphate). This change in the solid phase of warfarin leads to significant changes in dissolution, especially with the different particle sizes of the APIs in the tablet. Thus, the choice of suitable excipients and particle sizes are critical factors influencing the safety of generic warfarin sodium tablets.

Evaluation of Bleeding Rate and Time in Therapeutic Range in Patients Using Warfarin Before and During the COVID-19 Pandemic-Warfarin Treatment in COVID-19

The treatment process of patients using warfarin is expected to be hindered during the COVID-19 pandemic. Therefore we investigated whether the time in therapeutic range (TTR) and bleeding complications were affected during the COVID-19 pandemic. 355 patients using warfarin were included between March 2019 to March 2021. Demographic parameters, INR (international normalized ratio), and bleeding rates were recorded retrospectively. The TTR value was calculated using Rosendaal’s method. The mean age of the patients was 61 ± 12 years and 55% of them were female. The mean TTR value during the COVID-19 pandemic was lower than the pre-COVID-19 period (56 ± 21 vs 68 ± 21, P < 0.001). Among the patients, 41% had a lack of outpatient INR control. During the COVID-19 pandemic, 71 (20%) patients using VKA suffered bleeding. Among patients with bleeding, approximately 60% did not seek medical help and 6% of patients performed self-reduction of the VKA dose. During the COVID-19 pandemic, TTR values have decreased with the lack of monitoring. Furthermore, the majority of patients did not seek medical help even in case of bleeding.

Implementation of warfarin to direct oral anticoagulant conversion initiative in pharmacist-run anticoagulation clinics during COVID-19 pandemic

Due to community transmission of coronavirus disease 2019 (COVID‐19), social distancing and stay‐at‐home orders were implemented statewide in an effort to limit the spread of disease. This posed unique challenges for patients on medications requiring close and continued monitoring by clinic staff, such as anticoagulation clinics. Thus, innovative measures were implemented at Cleveland Clinic Health System (CCHS) to maintain the health and care of ambulatory patients. An initiative to evaluate patients for warfarin to direct oral anticoagulants (DOAC) conversion was used in the pharmacist‐run anticoagulation clinics. This article describes how patients were screened for eligibility, the education to pharmacists, the utilization of student learners in the process, and the workflow for provider notification of conversion. Follow up monitoring, challenges encountered, and future directions are also described.

Appointment attendance and patient perception of drive-up INR testing in a rural anticoagulation clinic during the COVID-19 pandemic

INTRODUCTION

The Anticoagulation Forum and Centers for Disease Control and Prevention (CDC) recommend drive-up international normalized ratio (INR) testing to combat INR non-adherence and increase safety during the coronavirus disease 2019 (COVID-19) pandemic. Patient perceptions and impact on attendance have not been studied.

OBJECTIVE

To assess appointment volume and patient perception after initiation of drive-up INR testing in a rural pharmacist-managed anticoagulation clinic.

METHODS

This cross-sectional cohort survey study offered each patient attending the anticoagulation clinic via drive-up or in-office visit a survey between May 27 and July 2, 2020. Patients testing off-site were excluded. Study end points included monthly patient volume, visit type preference, testing barriers, desired drive-up duration, and overall clinic satisfaction. Clinic appointment volume from October 2019 to June 2020 was collected retrospectively through a schedule review.

RESULTS

Sixty-four (80%) of 80 surveys offered were completed: 46.6% of respondents preferred drive-up testing, 26.7% indifferent, and 26.7% preferred in-office visits; 38.7% of respondents indicated a greater likelihood of continuing routine INR monitoring via drive-up testing. Of the respondents completing the survey curbside, 46% and 27% of respondents identified reduced COVID-19 transmission risk and ease of transportation as benefits of drive-up INR testing, respectively. March and April clinic volumes were 19% and 22% below average, respectively, returning to baseline after drive-up testing was implemented. Clinic rating before and after drive-up testing remained high at 2.75 on a scale of 0-3. While infection risk was identified as the biggest barrier to care by 32.8% of respondents, 59.3% of all respondents wanted drive-up testing to continue indefinitely.

CONCLUSIONS

Drive-up INR testing improves patient attendance during the COVID-19 pandemic. Patient perception of drive-up testing is positive. About 46% of respondents preferred drive-up INR testing with telehealth follow-up and 59.3% of respondents want drive-up testing to continue indefinitely, which suggests this approach to INR testing as a potential method to allay barriers to routine monitoring beyond the scope of the pandemic.

A review of indications and comorbidities in which warfarin may be the preferred oral anticoagulant

WHAT IS KNOWN AND OBJECTIVE

Direct oral anticoagulants (DOACs) are increasingly prescribed instead of warfarin for chronic anticoagulation for ease of dosing, fewer interactions, and less stringent monitoring. However, it is important to consider indications and comorbidities for which warfarin is still the preferred anticoagulant. This review aims to capture these clinical scenarios in which warfarin may still be preferred over DOACs.

METHODS

We undertook a comprehensive literature search using the PubMed database. Key search terms were based on DOAC clinical trial exclusion criteria, as well as indications and conditions in which the use of DOACs for anticoagulation has suggested harm. Society guidelines and tertiary literature were used to inform expert opinion where necessary. Studies were included if they investigated the use of DOACs or warfarin in the identified indications or conditions.

RESULTS AND DISCUSSION

Currently, evidence for the use of warfarin over DOACs for anticoagulation is strongest for patients with prosthetic valves, antiphospholipid syndrome, or a high risk of gastrointestinal bleeding. For several clinical situations, including mitral stenosis, obesity, altered gastrointestinal anatomy, pulmonary arterial hypertension, renal or hepatic impairment, and left ventricular thrombus, evidence is lacking but may eventually support the use of DOACs. Depending on indication and condition, appropriateness of DOAC use may vary by agent.

WHAT IS NEW AND CONCLUSION

New evidence continues to support new indications and conditions in which DOACs may be appropriate to use for anticoagulation. There are key clinical scenarios, however, in which emerging literature continues to support warfarin as the preferred anticoagulant.

Aminotransferases disorders associated with venous thromboembolic events in patients infected with COVID-19

INTRODUCTION AND OBJECTIVES

Since the outbreak of the COVID-19 pandemic, increasing evidence suggests that infected patients present a high incidence of venous thromboembolic (VTE) events and elevated aminotransferases (AT).The objective of this work was to evaluate the incidence of aminotransferases disorders in patients infected with COVID-19 and to manage the VTE events associated with elevated AT.

PATIENTS OR MATERIALS AND METHODS

We report a retrospective study of 46 patients admitted for COVID-19 infection. Venous duplex ultrasound of lower limbs was performed in all patients at Day 0 and Day 5. All patients had antithrombotic-prophylaxis upon admission using low molecular weight heparin with Enoxaparin. Demographics, comorbidities and laboratory parameters were collected and analyzed.

RESULTS

Elevated AT were reported in 28 patients (61%). 10 had acute VTE events of which eight (17.4%) had aminotransferases disorders. They had been treated with curative Enoxaparin. After a follow-up of 15 and/or 30 days, six of them were controlled, and treated with direct oral anticoagulant (DOACs) after normalization of aminotransferases.

CONCLUSIONS

The incidence of aminotransferases disorders associated with acute VTE events in patients infected with COVID-19 is significant. The use of DOACs appear pertinent in these patients. Monitoring of the liver balance should therefore be considered at a distance from the acute episode in the perspective of DOACs relay.