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

Clinical versus fixed warfarin dosing and the impact on quality of anticoagulation (The ClinFix trial)

Different dosing strategies exist to initiate warfarin, most commonly fixed warfarin dosing (FWD), clinical warfarin dosing (CWD), and genetic-guided warfarin dosing (GWD). Landmark trials have shown GWD to be superior when compared to FWD in the EU-PACT trial or CWD in the GIFT trial. COAG trial did not show differences between GWD and CWD. We aim to compare the anticoagulation quality outcomes of CWD and FWD. This is a prospective cohort study with a retrospective comparator. Recruited subjects in the CWD (prospective) arm were initiated on warfarin according to the clinical dosing component of the algorithm published in www.warfarindosing.org. The primary efficacy outcome was the percentage time in the therapeutic range (PTTR) from day 3 to 6 till day 28 to 35. The study enrolled 122 and 123 patients in the CWD and FWD, respectively. The PTTR did not differ statistically between CWD and FWD (62.2 ± 26.2% vs. 58 ± 25.4%, p = 0.2). There was also no difference between both arms in the percentage of visits with extreme subtherapeutic international normalized ratio (INR) (<1.5; 15 ± 18.3% vs. 16.8 ± 19.1%, p = 0.44) or extreme supratherapeutic INR (>4; 7.7 ± 14.7% vs. 7.5 ± 12.4%, p = 0.92). We conclude that CWD did not improve the anticoagulation quality parameters compared to the FWD method.

Evaluation of warfarin management in primary health care centers in Qatar: A retrospective cross-sectional analysis of the national dataset

BACKGROUND

Warfarin management is associated with severe complications, highlighting the critical need to evaluate the quality of its administration.

OBJECTIVES

To evaluate the quality of warfarin management for patients managed in primary healthcare centers by measuring the percentage of Time in Therapeutic Range (TTR) and the proportion of extreme out-of-range international normalized ratio (INR) values.

METHODS

This is a cross-sectional study. Data was extracted from a national dataset retrieved from the largest primary healthcare provider in Qatar. TTR was calculated using the traditional method. Inferential and descriptive analyses were performed as appropriate.

RESULTS

Four hundred ninety-four patients met the inclusion criteria. The mean (SD) TTR was 45.3 % (17.5). This was significantly lower than the recommended cutoff value (P<0.001). Extreme out-of-range INR accounted for 24.7 % of total INR readings.

CONCLUSIONS

The management of patients taking warfarin in Qatar is inadequate. More effective strategies are warranted to ensure safe and effective therapy.

Detection of α-Thrombin with Platelet Glycoprotein Ibα (GP1bα) for the Development of a Coagulation Marker

The detection of prothrombotic markers is crucial for understanding thromboembolism and assessing the effectiveness of anticoagulant drugs. α-Thrombin is a marker that plays a critical role in the coagulation cascade process. However, the detection of this enzymatic molecule was hindered by the absence of an efficient modality in the clinical environment. Previously, we reported that one α-thrombin interacts with two α-chains of glycoprotein Ib (GPIbα), i.e., multivalent protein binding (MPB), using bioresponsive hydrogel nanoparticles (nanogels) and optical microscopy. In this study, we demonstrated that GPIbα-mediated platforms led to the highly sensitive and quantitative detection of α-thrombin in various diagnostic systems. Initially, a bioresponsive nanogel-based surface plasmon resonance (nSPR) assay was developed that responds to the MPB of α-thrombin to GPIbα. The use of GPIbα for the detection of α-thrombin was further validated using the enzyme-linked immunosorbent assay, which is a gold-standard protein detection technique. Additionally, GPIbα-functionalized latex beads were developed to perform latex agglutination (LA) assays, which are widely used with hospital diagnostic instruments. Notably, the nSPR and LA assays exhibited a nearly 1000-fold improvement in sensitivity for α-thrombin detection compared to our previous optical microscopy method. The superiority of our GPIbα-mediated platforms lies in their stability for α-thrombin detection through protein-protein interactions. By contrast, assays relying on α-thrombin enzymatic activity using substrates face the challenge of a rapid decrease in postsample collection. These results suggested that the MPB of α-thrombin to GPIbα is an ideal mode for clinical α-thrombin detection, particularly in outpatient settings.

Fibrinogen, Coagulation, and Ageing

The World Health Organization estimates that the world's population over 60 years of age will nearly double in the next 30 years. This change imposes increasing demands on health and social services with increased disease burden in older people, hereafter defined as people aged 60 years or more. An older population will have a greater incidence of cardiovascular disease partly due to higher levels of blood fibrinogen, increased levels of some coagulation factors, and increased platelet activity. These factors lead to a hypercoagulable state which can alter haemostasis, causing an imbalance in appropriate coagulation, which plays a crucial role in the development of cardiovascular diseases. These changes in haemostasis are not only affected by age but also by gender and the effects of hormones, or lack thereof in menopause for older females, ethnicity, other comorbidities, medication interactions, and overall health as we age. Another confounding factor is how we measure fibrinogen and coagulation through laboratory and point-of-care testing and how our decision-making on disease and treatment (including anticoagulation) is managed. It is known throughout life that in normal healthy individuals the levels of fibrinogen and coagulation factors change, however, reference intervals to guide diagnosis and management are based on only two life stages, paediatric, and adult ranges. There are no specific diagnostic guidelines based on reference intervals for an older population. How ageing relates to alterations in haemostasis and the impact of the disease will be discussed in this chapter. Along with the effect of anticoagulation, laboratory testing of fibrinogen and coagulation, future directions, and implications will be presented.

Influence of Vitamin D Status on the Maintenance Dose of Warfarin in Patients Receiving Chronic Warfarin Therapy

INTRODUCTION

Considering the anticoagulant actions of vitamin D, we hypothesize that vitamin D status might affect the required dose of warfarin for maintaining the therapeutic international normalized ratio (INR).

METHODS

In a retrospective single-center cohort study, serum levels of 25-hydroxyvitamin D were assessed for 89 subjects receiving a stable dose of warfarin for 3 months or longer and had a stable INR between 2 and 3.5 for at least three consecutive visits. A warfarin sensitivity index (WSI), defined as the steady-state INR divided by the mean daily warfarin dose, was used for measuring the warfarin dose response. The relation between the serum level of 25-hydroxyvitamin D and WSI value and the difference in the mean WSI value between the subjects with different vitamin D status categories (sufficient, insufficient, and deficient) were assessed.

RESULTS

Twenty-one subjects had vitamin D deficiency, 43 had vitamin D insufficiency, and only 25 had normal levels of 25-hydroxyvitamin D. Based on the multiple linear regression analysis, there was a significant but weakly positive correlation between WSI and 25-hydroxyvitamin D serum levels, as the value of WSI increases by almost 0.0027434 for every unit increase in 25-hydroxyvitamin D serum level (p value = 0.041). Using one-way ANOVA analysis, there was a trend in a significant difference between the groups with different vitamin D status categories regarding the mean WSI value (F = 2.95, p value = 0.057), as subjects with sufficient vitamin D state compared to those with vitamin D deficiency had a higher WSI value.

CONCLUSIONS

Although the study's limitations limit our ability to draw definite conclusions, the present data suggest that in addition to other traditional factors, vitamin D status might also affect warfarin sensitivity and maintenance dose requirement. However, to more clearly explain this link, further studies with high involvement subjects are required.

Diagnostic and Therapeutic Challenges of Cerebral Venous Thrombosis in SARS-CoV-2 Infection: A Case Report and Review of Literature

Headache, a common prodromal symptom of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can also be a manifestation of cerebral venous thrombosis (CVT), secondary to COVID-19. CVT management continues to evolve, with direct oral anticoagulants (DOACs) emerging as an alternative to warfarin. A 44-year-old Asian female, with no past medical history, presented to the emergency room (ER) with complaints of nonproductive cough and left-sided headache. She denied a history of COVID-19 vaccination, and SARS-CoV-2 testing (with reverse transcriptase-polymerase chain reaction) was positive. Non-contrast computed tomography (CT) of the head revealed left transverse sinus hyperdensity, consistent with dense vein sign, and magnetic resonance venography (MRV) confirmed the presence of thrombus. The initial treatment included subcutaneous enoxaparin with headache resolution, and she was discharged on apixaban. Five weeks later, a non-contrast head CT showed resolution of the dense vein sign and recanalisation of left transverse sinus was seen on MRV. This report has highlighted the need for increased awareness of coagulopathy and thrombotic events, including cerebral venous thrombosis, in patients infected with SARS-CoV-2. Unremitting headache, in context of SARS-CoV-2 infection, should be evaluated with appropriate neurovascular imaging. Controlled studies are required to compare the safety and efficacy of DOACs with warfarin for management of cerebral venous thrombosis.