Managing oral anticoagulant therapy

Direct factor Xa inhibitors versus low molecular weight heparins or vitamin K antagonists for prevention of venous thromboembolism in elective primary hip or knee replacement or hip fracture repair

BACKGROUND

People undergoing major orthopaedic surgery are at increased risk of postoperative thromboembolic events. Low molecular weight heparins (LMWHs) are recommended for thromboprophylaxis in this population. New oral anticoagulants, including direct factor Xa inhibitors, are recommended as alternatives. They may have more advantages than disadvantages compared to LMWHs and vitamin K antagonists (VKAs, another type of anticoagulant).

OBJECTIVES

To assess the benefits and harms of prophylactic anticoagulation with direct factor Xa inhibitors compared with low molecular weight heparins and vitamin K antagonists in people undergoing major orthopaedic surgery for elective total hip or knee replacement or hip fracture surgery.

SEARCH METHODS

We searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, two other databases, and two trial registers to 11 November 2023. We conducted reference checks to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing the effects of direct factor Xa inhibitors to LMWHs or VKAs in people undergoing major orthopaedic surgery.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were all-cause mortality, major venous thromboembolism (VTE), symptomatic VTE, major bleeding, and serious hepatic and non-hepatic adverse events. We evaluated the risk of bias in the included studies using Cochrane's risk of bias 1 tool. We calculated estimates of treatment effects using risk ratios (RR) with 95% confidence intervals (CIs), and used GRADE criteria to assess the certainty of the evidence.

MAIN RESULTS

We included 53 RCTs (44,371 participants). Participants' average age was 64 years (range: 18 to 93 years). Only one RCT compared a VKA with direct factor Xa inhibitors. All 53 RCTs compared direct factor Xa inhibitors with LMWHs. Twenty-three studies included participants undergoing total hip replacement; 21 studies, total knee replacement; and three studies included people having hip fracture surgery. The studies' average duration was approximately 42 days (range: two to 720 days). Compared to LMWHs, direct factor Xa inhibitors may have little to no effect on all-cause mortality, but the evidence is very uncertain (RR 0.83, 95% CI 0.52 to 1.31; I2 = 0%; 28 studies, 29,698 participants; very low-certainty evidence). Direct factor Xa inhibitors may make little to no difference to major venous thromboembolic events compared to LMWHs, but the evidence is very uncertain (RR 0.51, 95% CI 0.37 to 0.71; absolute risk difference: 12 fewer major VTE events per 1000 participants, 95% CI 16 fewer to 7 fewer; I2 = 48%; 28 studies, 24,574 participants; very low-certainty evidence). Compared to LMWHs, direct factor Xa inhibitors may reduce symptomatic VTE (RR 0.64, 95% CI 0.50 to 0.83; I2 = 0%; 33 studies, 31,670 participants; low-certainty evidence). The absolute benefit of substituting factor Xa inhibitors for LMWHs may be between two and five fewer symptomatic VTE episodes per 1000 patients. In the meta-analysis with all studies pooled, direct factor Xa inhibitors appeared to make little or no difference to major bleeding compared to LMWHs, but the evidence was very uncertain (RR 1.05, 95% CI 0.86 to 1.30; I2 = 15%; 36 studies, 39,778 participants; very low certainty-evidence). • In a subgroup analysis limited to studies comparing rivaroxaban to LMWHs, people given rivaroxaban may have had more major bleeding events (RR 1.94, 95% CI 1.26 to 2.98; I2 = 0%; 17 studies, 17,630 participants; low-certainty evidence). The absolute risk of substituting rivaroxaban for LMWH may be between one and seven more major bleeding events per 1000 patients. • In a subgroup analysis limited to studies comparing direct factor Xa inhibitors other than rivaroxaban to LMWHs, people given these other direct factor Xa inhibitors may have had fewer major bleeding events, but the evidence was very uncertain (RR 0.80, 95% CI 0.63 to 1.02; absolute risk difference: 3 fewer major bleeding events per 1000 participants, 95% CI 5 fewer to 0 fewer; I2 = 0%; 19 studies, 22,148 participants; very low-certainty evidence). Direct factor Xa inhibitors may make little to no difference in serious hepatic adverse events compared to LMWHs, but the evidence is very uncertain (RR 3.01, 95% CI 0.12 to 73.93; 2 studies, 3169 participants; very low-certainty evidence). Only two studies reported this outcome, with one death in the intervention group due to hepatitis reported in one study, and no events reported in the other study. People given direct factor Xa inhibitors may have a lower risk of serious non-hepatic adverse events than those given LMWHs (RR 0.89, 95% CI 0.81 to 0.97; I2 = 18%; 15 studies, 26,246 participants; low-certainty evidence). The absolute benefit of substituting factor Xa inhibitors for LMWH may be between three and 14 fewer serious non-hepatic adverse events per 1000 patients. Only one study compared a direct factor Xa inhibitor with a VKA. It reported outcome data with imprecise results due to the small number of events. It showed no difference in the effects of the study drugs.

AUTHORS' CONCLUSIONS

Oral direct factor Xa inhibitors may have little to no effect on all-cause mortality, but the evidence is very uncertain. Oral direct factor Xa inhibitors may slightly reduce symptomatic VTE events when compared with LMWH. They may make little or no difference to major VTE events, but the evidence is very uncertain. In the evaluation of major bleeding, the evidence suggests rivaroxaban results in a slight increase in major bleeding events compared to LMWHs. The remaining oral direct factor Xa inhibitors may have little to no effect on major bleeding, but the evidence is very uncertain. Oral direct factor Xa inhibitors may reduce serious non-hepatic adverse events slightly compared to LMWHs. They may have little to no effect on serious hepatic adverse events, but the evidence is very uncertain. Due to the high rates of missing participants and selective outcome reporting, the effect estimates may be biased.

Warfarin overdose successfully treated using prophylactic vitamin K infusion without severe coagulopathy: A case report

Background

Warfarin, a vitamin K antagonist, is widely used for preventing and treating thromboembolic diseases. While guidelines exist for managing elevated prothrombin time-international normalized ratio (INR) in patients on warfarin, the treatment for warfarin overdose in these patients is yet to be standardized.

Case Presentation

A 41-year-old woman ingested 230 mg of warfarin with suicidal intent, along with other medications. Initially unconscious, her INR was 1.0, and laboratory results were normal. Prophylactic continuous menaquinone-4, vitamin K2, injections were administered before the INR increased. After stopping vitamin K2 72 h later, her INR rose to 1.8, but she recovered without severe coagulopathy or bleeding, despite a high initial warfarin concentration.

Conclusion

This is the first case of warfarin overdose managed with prophylactic vitamin K2 injections before INR elevation, successfully preventing severe complications. Prophylactic vitamin K infusion may be a practical approach for warfarin overdose treatment in non-dependent patients.

Exploring the association between atrial fibrillation and celiac disease: a comprehensive review

Objective

This paper aims to provide a comprehensive overview of the pathophysiology of atrial fibrillation (AF) and celiac disease (CD) individually while also exploring the emerging evidence of a potential association between the two conditions.

Methods

The pathophysiology of AF, the most prevalent arrhythmia globally, and CD, an autoimmune condition triggered by gluten consumption, is examined. Genetic, structural, electrophysiological, and inflammatory factors contributing to their development are explored.

Results

AF involves irregular atrial activity leading to electrical and structural remodeling of the atrium. CD is characterized by an immune response to gluten, primarily associated with HLA-DQ2 and HLA-DQ8 genetic mutations, resulting in damage to intestinal tissue. Emerging research suggests a link between AF and CD, possibly mediated through inflammation, fibrosis, and electromechanical delays in the atrium.

Conclusion

Understanding the association between AF and CD carries significant clinical implications. Recognition of this relationship can assist in identifying individuals at higher risk for AF and inform proactive management strategies. Additionally, it underscores the importance of comprehensive care for CD patients, considering potential cardiac implications. Further research is warranted to elucidate precise mechanisms and explore potential therapeutic interventions targeting common pathways, opening avenues for enhanced patient care and future investigations.

The 2023 WSES guidelines on the management of trauma in elderly and frail patients

BACKGROUND

The trauma mortality rate is higher in the elderly compared with younger patients. Ageing is associated with physiological changes in multiple systems and correlated with frailty. Frailty is a risk factor for mortality in elderly trauma patients. We aim to provide evidence-based guidelines for the management of geriatric trauma patients to improve it and reduce futile procedures.

METHODS

Six working groups of expert acute care and trauma surgeons reviewed extensively the literature according to the topic and the PICO question assigned. Statements and recommendations were assessed according to the GRADE methodology and approved by a consensus of experts in the field at the 10th international congress of the WSES in 2023.

RESULTS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage, including drug history, frailty assessment, nutritional status, and early activation of trauma protocol to improve outcomes. Acute trauma pain in the elderly has to be managed in a multimodal analgesic approach, to avoid side effects of opioid use. Antibiotic prophylaxis is recommended in penetrating (abdominal, thoracic) trauma, in severely burned and in open fractures elderly patients to decrease septic complications. Antibiotics are not recommended in blunt trauma in the absence of signs of sepsis and septic shock. Venous thromboembolism prophylaxis with LMWH or UFH should be administrated as soon as possible in high and moderate-risk elderly trauma patients according to the renal function, weight of the patient and bleeding risk. A palliative care team should be involved as soon as possible to discuss the end of life in a multidisciplinary approach considering the patient's directives, family feelings and representatives' desires, and all decisions should be shared.

CONCLUSIONS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage based on assessing frailty and early activation of trauma protocol to improve outcomes. Geriatric Intensive Care Units are needed to care for elderly and frail trauma patients in a multidisciplinary approach to decrease mortality and improve outcomes.

Effect of rt-PA on Shear Wave Mechanical Assessment and Quantitative Ultrasound Properties of Blood Clot Kinetics In Vitro

OBJECTIVE

The consequences associated with blood clots are numerous and are responsible for many deaths worldwide. The assessment of treatment efficacy is necessary for patient follow-up and to detect treatment-resistant patients. The aim of this study was to characterize the effect of treatment on blood clots in vitro using quantitative ultrasound parameters.

METHODS

Blood from 10 pigs was collected to form three clots per pig in gelatin phantoms. Clots were subjected to 1) no treatment, 2) rt-PA (recombinant tissue plasminogen activator) treatment after 20 minutes of clotting, and 3) rt-PA treatment after 60 minutes of clotting. Clots were weighted before and after the experiment to assess the treatment effect by the mass loss. The clot kinetics was studied over 100 minutes using elastography (Young's modulus, shear wave dispersion, and shear wave attenuation). Homodyne K-distribution (HKD) parameters derived from speckle statistics were also studied during clot formation and dissolving (diffuse-to-total signal power ratio and intensity parameters).

RESULTS

Treated clots loosed significantly more mass than non-treated ones (P < .005). A significant increase in Young's modulus was observed over time (P < .001), and significant reductions were seen for treated clots at 20 or 60 minutes compared with untreated ones (P < .001). The shear wave dispersion differed for treated clots at 60 minutes versus no treatments (P < .001). The shear wave attenuation decreased over time (P < .001), and was different for clots treated at 20 minutes versus no treatments (P < .031). The HKD intensity parameter varied over time (P < .032), and was lower for clots treated at 20 and 60 minutes than those untreated (P < .001 and P < .02).

CONCLUSION

The effect of rt-PA treatment could be confirmed by a decrease in Young's modulus and HKD intensity parameter. The shear wave dispersion and shear wave attenuation were sensitive to late and early treatments, respectively. The Young's modulus, shear wave attenuation, and HKD intensity parameter varied over time despite treatment.

Being precise with anticoagulation to reduce adverse drug reactions: are we there yet?

Anticoagulants are potent therapeutics widely used in medical and surgical settings, and the amount spent on anticoagulation is rising. Although warfarin remains a widely prescribed oral anticoagulant, prescriptions of direct oral anticoagulants (DOACs) have increased rapidly. Heparin-based parenteral anticoagulants include both unfractionated and low molecular weight heparins (LMWHs). In clinical practice, anticoagulants are generally well tolerated, although interindividual variability in response is apparent. This variability in anticoagulant response can lead to serious incident thrombosis, haemorrhage and off-target adverse reactions such as heparin-induced thrombocytopaenia (HIT). This review seeks to highlight the genetic, environmental and clinical factors associated with variability in anticoagulant response, and review the current evidence base for tailoring the drug, dose, and/or monitoring decisions to identified patient subgroups to improve anticoagulant safety. Areas that would benefit from further research are also identified. Validated variants in VKORC1, CYP2C9 and CYP4F2 constitute biomarkers for differential warfarin response and genotype-informed warfarin dosing has been shown to reduce adverse clinical events. Polymorphisms in CES1 appear relevant to dabigatran exposure but the genetic studies focusing on clinical outcomes such as bleeding are sparse. The influence of body weight on LMWH response merits further attention, as does the relationship between anti-Xa levels and clinical outcomes. Ultimately, safe and effective anticoagulation requires both a deeper parsing of factors contributing to variable response, and further prospective studies to determine optimal therapeutic strategies in identified higher risk subgroups.

Effectiveness and Health Outcomes of Collaborative Nurse Prescribing for Patients Anticoagulated with Antivitamin K in Primary Care: A Study Protocol

The development of collaborative nurse prescribing (NP) in Andalusia (Spain) in 2018 gives us the opportunity to measure the impact of this practice. Scientific evidence indicates that prescribing is not more costly when performed by nurses and, in fact, is more economical in some cases. The aim of this study is to determine the effects of NP on the effectiveness, health outcomes and adverse events related to prescribing including in the follow-up of patients treated with antivitamin K oral anticoagulants in primary care (PC) by nurses. The design is a randomized clinical trial. The population comprises 1208 anticoagulated patients in 2019. The sample size calculation considers an alpha error of 0.05, a power of 99% and an effect size of 0.5, resulting in 127 users per group. Therefore, a total sample of 254 participants is needed. However, as the project intends to treat patients it will include the universal sample that meets the criteria in the two health centers participating in the study, with 575 participants in total. Data collection was carried out in the PC District of the Alamillo-San Jerónimo Clinical Management Unit of Sevilla for one year from January 2020. Data analysis is performed using the SPSS Statistics 25 package. We intend to study if nurse collaborative prescription in the follow-up and management of patients taking antivitamin K oral anticoagulants in PC is as effective as the traditional approach to follow-ups carried out by a family physician.

Cost-Utility and Budget Impact Analysis of Implementing Anticoagulation Clinics and Point-of-Care Monitoring Devices in Anticoagulated Patients in Argentina

BACKGROUND

Worldwide, 1 % of the population receives anticoagulation therapy, with prevalence higher in older adults. Difficulties in the adequate management of these patients have led to the development of strategies focused on achieving therapeutic control and reducing adverse events with efficient use of resources.

OBJECTIVE

To estimate the cost utility and budget impact on the Argentinean health system of implementation of anticoagulation clinics (ACs) (with and without use of point-of-care [POC] CoaguChek^® devices [Roche Diagnostics International Ltd]) compared with the traditional laboratory method (non-AC settings) for the management of anticoagulated patients.

METHODS

For the cost-utility analysis, a cohort-based state transition model was designed to compare costs and health outcomes of implementing ACs for outpatient management of anticoagulated patients. The budget impact analysis used an analytical model to estimate the differential costs of implementing an AC and the expected adverse events avoided, and the differential costs of an international normalized ratio (INR) determination using a POC device rather than a conventional laboratory.

RESULTS

We calculated the study outcomes for a cohort of 1000 patients. Considering a 5 % discount rate, the use of ACs generated 13.9 additional quality-adjusted life-years (0.014 per patient) and 12.5 additional life-years (0.013 per patient). Incremental cost-effectiveness ratios of AC implementation with and without the use of POC devices compared with the scenario without ACs were dominant in both cases. In the probabilistic sensitivity analysis, nearly all simulated results were cost effective (i.e., below the 1 or 3 gross domestic product per capita thresholds). Budget impact analysis results showed AC implementation generated savings from the first year of implementation, with savings of AR $265,325 by year 5. The addition of POC devices in the ACs also generated savings as early as the first year of implementation, with savings of AR $488,072 by year 5 (AR $488 per patient).

CONCLUSIONS

Anticoagulation clinics are estimated to be cost effective and generate notable savings in the treatment of patients on long-term oral anticoagulant therapy when compared with non-AC settings. These savings are considerably higher when POC devices are added as part of the patient management, due to lower laboratory technician costs per INR determination.

A clinical study of genetic testing to guide the dosing of warfarin after heart valve replacement

Objective

To explore the role of genetic testing of VKORC1 and CYP2C9 in determining the dosage of warfarin after aortic valve replacement.

Methods

A total of 172 patients receiving warfarin after aortic valve replacement were divided into a control group (n = 86) and an experimental (n = 86) group based on acceptance of genetic testing. In the experimental group, three loci of VKORC1 and CYP2C9 were tested by polymerase chain reaction-restriction fragment length polymorphism technique, and the initial dose of warfarin was determined based on the genetic testing results and warfarin oral-dose table recommended by U.S. Food and Drug Administration (FDA). In the control group, warfarin (3 mg per night) was used as the initial dose. The international normalized ratio (INR) of each patient was continuously monitored after medication. The percentages of patients meeting the target INR in the two groups at specific time points and at 3-month follow-up after discharge from the hospital were monitored, and the incidence of various adverse events was compared between the groups.

Results

Based on the results of genetic testing, 68 patients received 3–4 mg/d (79.1%), 10 patients received 0.5–2 mg/d (11.6%), and eight patients received 5–7 mg/d (9.3%) as the initial dosages of warfarin in the experimental group. The percentages of the patients meeting the target INR on the third and sixth day of postoperative medication were 45.3% and 73.3%, respectively, in the experimental group, and 29.8% and 58.3%, respectively, in the control group. The INR critical values during hospitalization occurred in 2.3% in the experimental group and in 7.1% in the control group, while the percentage of the patients meeting the target INR after 3 months was 86.1% in the experimental group and 83.1% in the control group.

Conclusion

Genetic testing may guide the selection of the initial dose of warfarin after heart valve replacement to rapidly achieve a stable dose.

Therapeutic-Dose Warfarin (International Normalized Ratio >1.6) Plus Aspirin Improved Long-Term Patency of Saphenous Vein Graft without Bleeding Complication

Purpose: Saphenous vein graft (SVG) is the most commonly used conduits in coronary artery bypass grafting (CABG), but the disadvantage of SVG is its tendency for progressive failure. We hypothesized that therapeutic-dose warfarin (international normalized ratio [INR] >1.6) plus aspirin improve SVG patency. This study aimed to evaluate the factors contributing to SVG patency.

Methods: Since 2010–2020, 199 patients who underwent isolated CABG using SVG were divided into two groups according to their INR values in the first year: group T (INR >1.6) and group L (INR <1.6).

Results: Group T had 162 SVGs (105 patients) and group L had 151 SVGs (94 patients). The 1-, 4-, and 7-year SVG patency rates were higher in group T than in group L (99%, 96%, and 92% vs. 93%, 86%, and 79%, respectively; p = 0.00378). The 1-, 4-, and 7-year freedom from repeat-revascularization was higher in group T than in group L (100%, 100%, and 99% vs. 98%, 95%, and 87%, respectively; p = 0.0264). Multivariate analysis showed that therapeutic-dose warfarin (p = 0.00204) and target vessel diameter (p <0.0001) were independent risk factors of SVG occlusion.

Conclusion: Therapeutic-dose warfarin (INR >1.6) plus aspirin after CABG improved the long-term patency of SVG and decreased repeat-revascularization rate.

The Dilemma of Peri-Procedural Warfarin Management: A Narrative Review

Periprocedural vitamin K antagonist management is a complex process and inherently entails multiple clinical issues. Marked variations have been reported in different aspects of this process. These differences were noted at the clinician and institutional levels owing to the lack of evidence-based data leading to many discrepancies in decision-making. This review aims to address the gap of vitamin K antagonist periprocedural management acknowledged by previously published prescribers’ questionnaires. One of the components of this process is “bridging,” which aims to provide minimal interruption of the anticoagulation period through the use of heparin products. Recent studies showed that bridging is increasing bleeding risk. Secondly, interruption decision relies on the classification of thromboembolism risk which depends on trials that did not include patients with atrial fibrillation. Thirdly, the interruption duration is different among different International normalization ratio levels, which strengthens the difference in the clinical practice of preoperative vitamin K antagonist management. Lastly, the resumption of a vitamin-K antagonist after surgery has many scenarios according to the procedure and patient risk of bleeding. Vitamin-K antagonist periprocedural management is complicated due to individual practice and the lack of strictly implemented institutional standardized protocols to guide, manage and evaluate the process.

Safety and efficacy of low-dose non-vitamin K antagonist oral anticoagulants versus warfarin after left atrial appendage closure with the Watchman device

BACKGROUND/PURPOSE

Anticoagulant therapy is suggested within 45 days after Watchman device implantation for stroke prevention in patients with atrial fibrillation (AF). A previous study demonstrated that non-vitamin K antagonist oral anticoagulants (NOACs) were a feasible peri- and postprocedural alternative to warfarin. The present study aimed to compare the safety and efficacy of using different anticoagulants (low-dose NOACs vs. warfarin) within 45 days after Watchman device implantation in a Chinese population.

METHODS

Patients with successful Watchman device implantation from October 2014 to June 2020 were included. All patients received anticoagulants within 45 days after the procedure, and those patients were divided into three groups according to the type of postprocedural anticoagulants. Transesophageal echocardiography follow-up was performed 45 days post procedure to assess residual flow and the occurrence of device-related thrombus (DRT).

RESULTS

A total of 368 patients were enrolled in the study. The study population was divided into three groups: the warfarin group (n = 77), the dabigatran group (n = 165) and the rivaroxaban group (n = 126). Periprocedural major bleeding was higher in the warfarin group (2.6% vs. 0% vs. 0%, P = 0.043), while minor bleeding was comparable among the groups (3.9% vs. 1.2% vs. 0.8%, P = 0.230). No periprocedural transient ischemic attack/stroke occurred. At follow-up, the incidence of DRT was higher in the warfarin group than in the other groups (4.2% vs. 0.6% vs. 0.8%; P = 0.116), but the difference was not statistically significant. The rates of thromboembolic and bleeding events were similar in the three groups.

CONCLUSION

The safety and efficacy of low-dose dabigatran and rivaroxaban were comparable to those of warfarin within 45 days after Watchman device implantation in a Chinese population.

Risk of More Advanced Lesions at Hysterectomy after Initial Diagnosis of Non-Atypical Endometrial Hyperplasia in Patients with Postmenopausal Bleeding and Oral Anticoagulant Treatment

Background and Objectives: Endometrial hyperplasia (EH) is a precursor lesion to endometrial cancer (EC), and when cellular atypia is present, in 40% of cases, they are diagnosed with EC on hysterectomy. Usually, EH is clinically manifested by uterine bleeding. In patients with oral anticoagulant therapy (OAT), the uterus is the second most common source of bleeding. The aim of the study was to show that uterine bleeding in postmenopausal patients undergoing OAT may reveal precancerous endometrial lesions with atypia, or neoplastic lesions in patients with an initial diagnosis of endometrial hyperplasia without atypia (non-atypical endometrial hyperplasia, NAEH) on dilation and curettage (D&C). We will be able to estimate the risk of a postmenopausal female patient with uterine bleeding during an OAT to have a precancerous endometrial lesion. Materials and Methods: The subjects of the study were 173 female patients with uterine bleeding, who have had total hysterectomy with bilateral salpingoovarectomy, of whom 99 underwent an OAT. There were 101 female patients initially diagnosed with NAEH, of which 60 did not have anticoagulant treatment (mean age 57.36 ± 6.51) and 41 had anticoagulant treatment (mean age 60.39 ± 7.35) (p = 0.006). From the pathology diagnosis moment, the surgery was performed at 42.09 ± 14.54 days in patients without OAT and after 35.39 ± 11.29 days in those who received such treatment (p = 0.724). Results: Initial diagnosis of NAEH established at D&C was changed at the final diagnosis after hysterectomy in EH with cellular atypia (atypical endometrial hyperplasia AEH) or EC in 18.18% of patients without OAT, and in 40.54% of patients who received this treatment. Conclusions: Based on a logistic regression model, it is estimated that female patients with an initial histopathological diagnosis of NAEH and who underwent OAT have, on average, 4.85 times greater odds (OR = 4.85, 95% CI 1.79–14.06) than the others of being identified postoperatively with more advanced lesions.

Patient-related factors associated with oral anticoagulation control: a population-based cohort study

OBJECTIVES

Time in therapeutic range (TTR) of ≥70% is a commonly used indicator of optimal anticoagulation control. This study aimed to determine the patterns and predictors of anticoagulation control in a population-based cohort of new users of warfarin.

METHODS

This was a retrospective cohort study. All adults (age ≥18 years) who had been newly initiated on warfarin therapy between January 2006 and March 2011were selected from administrative health databases. TTR was calculated using the Rosendaal method. Multivariable logistic regression models were used to identify patient-related factors associated with optimal TTR. Predictors of patients spending >30% of time above and below the therapeutic international normalised ratio (INR) range were also examined.

KEY FINDINGS

A total of 6032 patients were included in this study. The mean TTR was 54.1 ± 18.8%, and 82.3% of patients had subthreshold TTR (<70%). Compared with New Zealand Europeans, Māori and Pacific people had decreased odds of achieving optimal TTR and increased odds of spending >30% of time below the therapeutic INR range. Patients aged 65-74 years and 75 years or older had increased odds of achieving optimal TTR but decreased odds of spending >30% of time below the therapeutic INR range than those <65 years. Compared with those living in the least socioeconomically deprived areas, those living in the most deprived areas had decreased odds of achieving optimal TTR.

CONCLUSIONS

Anticoagulation control with warfarin is suboptimal in routine care in New Zealand. Age, ethnicity and deprivation index were significant predictors of TTR. It is important to ensure equitable access to appropriate, high-quality care for those living in deprived areas and those from ethnic minority groups.

Barriers and facilitators to optimal oral anticoagulant management: a scoping review

Oral anticoagulants (OACs) are high alert medications and require high-quality management to optimize health outcomes. The objective of this scoping review was to identify barriers and facilitators (B&Fs) associated with the quality of OAC management. We searched MEDLINE, EMBASE, and CINAHL databases until July 12, 2018, and cross-referenced the bibliographies of the retrieved studies. We included quantitative and qualitative studies that assessed B&Fs to OAC management. The study selection and data extraction processes were performed in duplicate. Analyses included measuring the prevalence of reported B&Fs from studies reporting quantitative data, identifying B&Fs in narrative analyses, and identifying their impact on important outcomes of OAC management. B&Fs were coded and aggregated to higher-level themes using a consensus approach. Factors were described as "key" if they were statistically associated with important outcomes in a randomized trial or observational study. We included 62 studies-three randomized clinical trials (RCTs), 46 observational studies (cross-sectional studies, cohort studies, and case-control studies), 11 qualitative studies, and two mixed-methods studies. Factors identified could be grouped into four themes-therapy-related, patient-related, healthcare provider-related, and health system-related. Key barriers to optimal OAC management were mostly patient-related, whereas interventions focused on education or implementing protocols were shown through RCTs to be effective at improving knowledge scores of OAC patients. While multiple barriers and some facilitators were identified in this review, none was proven to be associated with clinical outcomes. With this in mind, individual physicians may wish to address the key barriers in their practice as a quality improvement initiative but system-wide or policy changes should await high-quality evidence. Future trials should address these factors.Systematic review registration: PROSPERO CRD42017069043.

An efficacy and safety study of rivaroxaban for the prevention of deep vein thrombosis in patients with left iliac vein compression treated with stent implantation (PLICTS): study protocol for a prospective randomized controlled trial

BACKGROUND

Balloon dilatation with stent implantation has been proved to be an effective option for left iliac vein compression syndrome (LIVCS), but thrombosis may still occur after the operation. Currently, warfarin is used for anticoagulant therapy, but long-term monitoring is required, while rivaroxaban does not need laboratory monitoring, which can simplify treatment. Therefore, this study aimed to compare the efficacy and safety of rivaroxaban and warfarin in anticoagulation.

METHODS

This study is a multicenter, randomized controlled trial. We will recruit 224 patients with thrombotic LIVCS from 9 hospitals. Moreover, these patients will be randomized to either the experimental group (rivaroxaban) or the control group (warfarin plus nadroparin). The primary outcome is stent occlusion rate. Secondary outcomes are quality of life scale survey results, all-cause mortality, anticoagulation-related mortality, and the proportion of participants with stent displacement/fracture, thrombosis, hemorrhage, and other vascular events.

DISCUSSION

This study will provide reliable, evidence-based clinical evidence for the efficacy and safety of rivaroxaban antithrombotic therapy after stent implantation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04067505 . Registered on August 26, 2019.

The effect of management models on thromboembolic and bleeding rates in anticoagulated patients: an ecological study

The primary study objective is to compare the outcomes of patients taking oral anticoagulant medications in two distinct populations treated according to different management models (comprehensive vs. usual care). (Design: regional prospective cohort study; setting: hospital admission data from two regions). Eligible partecipants were patients taking oral anticoagulant drugs (vitamin K antagonist or direct oral anticoagulants), residents in the Vicenza and Cremona districts from February 1st, 2016 to June 30th, 2017. Patients were identified by accessing the administrative databases of patient drug prescriptions. The primary study outcome was admission to the Emergency Department for stroke, systemic arterial embolism, recurrence of venous thromboembolism or major bleeding. The study evaluated outcomes in 14,226 patients taking oral anticoagulants, of whom 6725 being followed in Cremona with a comprehensive management model. There were 19 and 45 thromboembolic events over 6205 and 6530 patient-years in the Cremona and Vicenza cohort, respectively (IRR 0.44, 95% CI 0.24-0.77). The reduction of events in the Cremona cohort was almost entirely explained by a decrease of events in patients taking VKA (IRR 0.41, 95% CI 0.20-0.78) but not DOACs (IRR 1.08, 95% CI 0.25-5.24). The rate of major bleeding was non-significantly higher in Cremona than in Vicenza (IRI 1.32; 95% CI 0.74-2.40). Across the two cohorts, the risk of bleeding was lower in patients being treated with DOACs rather than warfarin (10/4574 vs. 42/8161 event/person-years, respectively, IRR 0.42 95% CI 0.19-0.86). We conclude that a comprehensive management model providing centralized dose prescription and follow-up may significantly reduce the rate of thromboembolic complications, without substantially increasing the number of bleeding complications. Patients treated with direct oral anticoagulants appear to have a rate of thromboembolic complications comparable to VKA patients under the best management model, with a reduction of major bleeding.

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.

The mythology of anticoagulation therapy interruption for dental surgery

BACKGROUND

Continuous anticoagulation therapy is used to prevent heart attacks, strokes, and other embolic complications. When patients receiving anticoagulation therapy undergo dental surgery, a decision must be made about whether to continue anticoagulation therapy and risk bleeding complications or briefly interrupt anticoagulation therapy and increase the risk of developing embolic complications. Results from decades of studies of thousands of dental patients receiving anticoagulation therapy reveal that bleeding complications requiring more than local measures for hemostasis have been rare and never fatal. However, embolic complications (some of which were fatal and others possibly permanently debilitating) sometimes have occurred in patients whose anticoagulation therapy was interrupted for dental procedures.

PRACTICAL IMPLICATIONS AND CONCLUSIONS

Although there is now virtually universal consensus among national medical and dental groups and other experts that anticoagulation therapy should not be interrupted for most dental surgery, there are still some arguments made supporting anticoagulation therapy interruption. An analysis of these arguments shows them to be based on a collection of myths and half-truths rather than on logical scientific conclusions. The time has come to stop anticoagulation therapy interruption for dental procedures.

Clinical Model for Predicting Warfarin Sensitivity

Warfarin is a widely used anticoagulant with a narrow therapeutic index and large interpatient variability in the therapeutic dose. Complications from inappropriate warfarin dosing are one of the most common reasons for emergency room visits. Approximately one third of warfarin dose variability results from common genetic variants. Therefore, it is very necessary to recognize warfarin sensitivity in individuals caused by genetic variants. Based on combined polymorphisms in CYP2C9 and VKORC1, we established a clinical classification for warfarin sensitivity. In the International Warfarin Pharmacogenetic Consortium (IWPC) with 5542 patients, we found that 95.1% of the Black in the IWPC cohort were normal warfarin responders, while 74.8% of the Asian were warfarin sensitive (P < 0.001). Moreover, we created a clinical algorithm to predict warfarin sensitivity in individual patients using logistic regression. Compared to a fixed-dose approach, the clinical algorithm provided significantly better performance. In addition, we validated the derived clinical algorithm using the external Easton cohort with 106 chronic warfarin users. The AUC was 0.836 vs. 0.867 for the Easton cohort and the IWPC cohort, respectively. With the use of this algorithm, it is very likely to facilitate patient care regarding warfarin therapy, thereby improving clinical outcomes.

[Efficiency of pharmacogenetic approach to anticoagulant therapy in patients with prosthetic heart valves]

BACKGROUND

This study examined clinical, demographic, anthropometric, and inheritance factors that influence individual sensitivity to warfarin therapy after heart valve surgery. The clinical significance of the pharmacogenetic approach was assessed using the individual time frame and time spent in the INR therapeutic range.

AIMS

We determined the clinical outcome of the pharmacogenetic approach at the start of warfarin therapy in patients with prosthetic heart valves.

MATERIALS AND METHODS

The study included 915 patients, of which 512 women and 403 men (mean age 56±10 years), living in Western Siberia. Rheumatic heart disease was the main diagnosis that caused the acquired defect. Mechanical prostheses were used in 70% of cases of cardiac surgery. Real-time polymerase chain reaction used for molecular genetic testing.

RESULTS

The frequencies of the alleles and genotypes of CYP2C9 and VKORC1 in the study population of patients with heart valves prosthetic correspond to the distribution in Caucasoid populations. The use of pharmacogenetic testing results at the beginning of warfarin therapy reduced the time required for selecting a therapeutic dose of anticoagulant by 2 times and increased the duration of stay in the INR therapeutic range by 20.2%.

CONCLUSION

The use of the pharmacogenetic approach at the begin‑ ning of warfarin therapy contributes to the effectiveness and safety of anticoagulant therapy in this category of patients.

Cost of Healthcare Associated With Deep Vein Thrombosis in Patients Treated With Warfarin in Turkey: 2010-2013 Database Analysis of a Tertiary Care Center

OBJECTIVES

To evaluate the cost of healthcare with respect to the quality of anticoagulation in patients with deep vein thrombosis (DVT) treated with warfarin in daily practice via the database analysis of a tertiary care center in the period 2010 to 2013.

METHODS

Of 258 307 records in total, 42 582 unique patients with DVT and 32 012 patients with international normalized ratio (INR) measurements were included. Overall, 6720 unique patients with DVT diagnosis and one or more INR measurements were identified, and the records of 4377 out of 6720 unique patients were validated and included in the analysis data set. The cost analysis was based on direct medical costs from the payer's perspective. Cost items were related to healthcare resource utilization (inpatient and outpatient services) during the study period, which provided a basis for calculation of per-patient, outpatient, inpatient, and total direct medical costs.

RESULTS

Mean outpatient, inpatient, and total hospital admission costs were $578, $2195, and $2785, respectively, for patients with time in the therapeutic range of 70% or more, whereas the same costs were $571, $2163, and $3192, respectively, for patients with time in the therapeutic range of less than 70%.

CONCLUSIONS

Our findings for a retrospective cohort of patients with DVT undergoing warfarin therapy reveal that patients spent 70% or more, as opposed to less than 70%, of follow-up time within the therapeutic INR range and that outpatient care, as opposed to inpatient care, was associated with lower healthcare costs. Given the significant contribution that hospital stay makes to the cost burden of DVT, our findings also highlight the association between poor warfarin anticoagulant control and increased hospitalization costs.

Updated meta-analysis on prevention of venous thromboembolism in ambulatory cancer patients

Randomized clinical trials have evaluated the role of anticoagulants in the prevention of venous thromboembolism (VTE) in ambulatory cancer patients treated with chemotherapy. This meta-analysis is aimed at providing an updated evaluation of the efficacy and safety of anticoagulant prophylaxis in this clinical setting. Medline and Scopus were searched to retrieve randomized controlled trials on the prevention of VTE in ambulatory cancer patients. Two groups of trials were identified with VTE or death as the primary outcome, respectively. VTE was the primary outcome of this analysis. Anticoagulant prophylaxis reduced the incidence of VTE in studies in which the primary outcome was VTE [14 studies, 8,226 patients; odds ratio (OR)=0.45; 95% confidence interval (95% CI): 0.36-0.56] or death (8 studies, 3,727 patients; OR=0.61; 95% CI: 0.47-0.81). When these studies were pooled together, VTE was reduced by 49% (95% CI: 0.43-0.61) with no significant increase in major bleeding (OR=1.30, 95% CI: 0.98-1.73). The risk of major bleeding was increased in studies with VTE as the primary outcome (OR=1.43, 95% CI: 1.01-2.04). Similar reductions of VTE were observed in studies with parenteral (OR=0.43, 95% CI: 0.33-0.56) or oral anticoagulants (OR=0.49, 95% CI: 0.33-0.74). The reduction in VTE was confirmed in patients with lung (OR=0.42, 95% CI: 0.26-0.67) or pancreatic cancer (OR=0.26, 95% CI: 0.14-0.48), in estimated high-risk patients, in high-quality studies and with respect to symptomatic VTE. In conclusion, prophylaxis with oral or parenteral anticoagulants reduces the risk of VTE in ambulatory cancer patients, with an acceptable increase in major bleeding.

Pharmacist-led medicine use review in community pharmacy for patients on warfarin

Background Medicine use review by pharmacists has the potential to improve anticoagulation therapy management in patients on warfarin. Objective To develop, implement and evaluate a pharmacist-led medication use review service for patients on warfarin. Setting Six community pharmacies in Malta. Method Patients (N = 100) aged 18 or older and on warfarin were recruited through pre-selected community-pharmacies. These patients were then invited to attend two sessions: a review session (t₁) and a follow-up session after 2 months (t₂). During the medication use review session, medication reconciliation was performed (a) to detect drug-related problems using the DOCUMENT classification system, (b) to develop an individualised care plan for each patient and (c) to recommend an action for each identified problem for physician, pharmacist or patient consideration. At t₂, the degree of acceptance of the recommendations was determined by assessing the number of drug-related problems for which action was taken to address the problem. International normalisation ration (INR) control was evaluated by calculating the percentage Time in Therapeutic Range (TTR) at t₁ and t₂ using the Rosendaal linear interpolation method. Main outcome measures Frequency and type of drug-related problems detected; percentage of accepted recommendations; and INR control. Results A total of 481 drug-related problems were identified; 40% (n = 190) were related to warfarin treatment. Need for monitoring (30%; n = 145), lack of compliance (20%; n = 97) and need for patient education (19%; n = 90) were the top three problems identified. There was a significant correlation between frequency of the problems and number of chronic medications (Spearman Correlation 0.583, p < 0.001), number of comorbidities (Spearman Correlation 0.327, p = 0.001) and older age (Spearman Correlation 0.285, p = 0.04). A total of 475 recommendations were followed-up; 49% (n = 234) were referred for consideration by the physician. The percentage of recommendations accepted (84%; n = 397) was significantly higher than the percentage of recommendations not accepted (16%; n = 78) (p < 0.001). The time in therapeutic range improved significantly from 68.7% at t₁ to 79.8% at t₂ (p = 0.01). Conclusions The high percentage of accepted recommendations and the improvement in INR control indicate that a pharmacist-led medication use review service in community pharmacy contributes to improving anticoagulation therapy management in patients on warfarin.

A turbulence in vitro assessment of On-X and St Jude Medical prostheses

OBJECTIVE

The objective of this study was to investigate and compare the hemodynamic and turbulence characteristics upon implantation of St Jude Medical (SJM) (St Jude Medical, St Paul, Minn) and On-X (On-X Life Technologies, Kennesaw, Ga) bileaflet mechanical valves. Both valves are considered highly successful bileaflet mechanical valves characterized by good clinical outcomes despite their numerous design differences. Although thromboembolism remains the main disadvantage of bileaflet mechanical valves, On-X valves have been shown to need less anticoagulation therapy.

METHODS

Hemodynamic assessment of a 23-mm On-X bileaflet mechanical valve and a 23-mm bileaflet SJM valve implanted in an aortic root was performed under pulsatile physiologic conditions. Time-resolved and phase-locked particle-image-velocimetry images and high-speed imaging data were acquired. Pressure gradients, effective orifice areas, dimensionless area index, leaflet position tracking, velocity, and principal Reynolds shear stress were calculated.

RESULTS

Pressure gradient for the On-X valve was 4.15 ± 0.099 mm Hg versus 4.75 ± 0.048 mm Hg for SJM (P < .001). Effective orifice area for the On-X valve was 2.61 ± 0.045 cm² versus 2.36 ± 0.022 cm² for SJM (P < .001). Area index was higher with SJM (0.87 ± 0.008) than with On-X (0.73 ± 0.013) (P < .001). On-X showed fluctuating leaflet behavior during systole, whereas SJM leaflets were stable. At peak systole, the maximal velocity with On-X was 1.86 m/s versus 2.33 m/s with SJM. Reynolds shear stress was higher with On-X compared with SJM at peak systole (95 vs 72 Pa). Higher velocity fluctuation was noted with the On-X valve.

CONCLUSIONS

This study shows that despite the design differences that characterize the On-X valve, the hemodynamic and turbulence parameters were not necessarily improved compared with SJM.

Reduction of Pressure Gradient and Turbulence Using Vortex Generators in Prosthetic Heart Valves

Blood damage and platelet activation are inherent problems with present day bi-leaflet mechanical heart valve designs. Passive flow control through different arrangements of vortex generators (VG) as means of improving pressure gradients and reducing turbulence are investigated. Rectangular VG arrays were mounted on the downstream surfaces of a 23 mm 3D printed mechanical valve. The effect of VGs on the resulting flow structures were assessed under pulsatile physiological flow conditions where high resolution particle image velocimetry measurement was performed. The co-rotating VGs showed lower Reynolds shear stresses and improved pressure gradients (PG) compared with the counter-rotating ones and the no-VG control one (that showed higher turbulence). RSS was found 38.13 ± 0.89, 12.95 ± 0.32, 15.75 ± 0.71, 24.54 ± 0.84 and 16.33 ± 0.58 Pa for the control, co-rotating VGs, 8 counter-rotating VGs, 4 far-spaced VGs and 4 closely-spaced VGs, respectively. PG of 10.45 ± 0.94 mmHg was obtained with co-rotating VGs and the difference was significant compared with the other configurations (control 14.88 ± 0.4 mmHg; 8 counter-rotating VGs 13.76 ± 0.51 mmHg; 4 far-spaced VGs 13.84 ± 0.09 mmHg; and 4 closely-spaced VGs 15.37 ± 0.16 mmHg). Co-rotating VGs for this application induce a more delayed flow separation and a more homogenized and streamlined transition of flow compared with the counter-rotating VGs. Passive flow control techniques deployed on BHMVs is potentially beneficial as significant control of flow at small length scales without inducing large-scale design modifications of the valve.

Variability in the Calculation of Time in Therapeutic Range for the Quality Control Measurement of Warfarin

Time in therapeutic range (TTR), a well-recognized performance metric of oral anticoagulation, measures the time when patients' international normalized ratios (INRs) are within the desired range. The TTR value can vary significantly depending on the type of method used and can be a skewed indicator of the overall quality of anticoagulation. As such, the present study was designed to compare three methods for TTR calculation (cross-sectional, traditional, and Rosendaal) to quantify their differences, biases, and trends. As part of this investigation, a 21-week retrospective analysis of patients on warfarin was conducted to compare TTR values obtained by these three methods. Paired t-tests, correlation studies between size and bias, and Bland-Altman plots were performed using SAS 9.4 (SAS Institute, Cary, NC, USA). It was revealed that the TTR values for the cross-sectional, Rosendaal, and traditional methods were 65.97, 58.12, and 51.55, respectively. The addition of tolerances to INR ranges of ± 0.2 and ± 0.5 increased TTR values to 81.79 and 91.53, respectively, for the cross-sectional method, and 66.86 and 82.69, respectively, for the traditional method. The use of the traditional method resulted in significantly higher TTR values than did use of the Rosendaal method, with high variability between the methods in both positive and negative directions. There was a demonstrated lack of independence between the methods, and zero bias could not be assumed. In conclusion, the different methods considered in the present study do not accurately measure whether a patient is in or out of the therapeutic range, and the addition of tolerances can further distort the perception of anticoagulation achieved. We recommend a standardized TTR calculation method as well as a uniform tolerance for use in clinical trials and quality control efforts.

Recommendations for the post-operative management of an existing Warfarin therapy after lower limb joint arthroplasty

BACKGROUND

Warfarin administration after lower limb joint replacements is associated with a high bleeding risk, creating the circumstances for periprosthetic joint infections, increased treatment costs and prolonged Length of Stay (L.o.S). We believe that previously warfarinized patients can be treated safely and discharged without delays, if appropriate policies are established and adhered to.

METHODS

This is a retrospective cohort study. We have collected and analyzed data from an audit cycle between 2012 and 2015 on: 1) the post-operative Warfarin reloading protocol, identifying 4 distinct patterns: usual dose, 1.5 times or double the usual dose for 2 days and overloading, 2) timing of reloading: Evening of Surgery vs post-op Day 1, 3) frequency of INR testing: daily vs intermittent, 4) time required to reach a therapeutic INR value ≥2.0, 5) rate of INR variations ≥4.0 and 6) bleeding complications, 7) and the overall L.o.S.

RESULTS

We found a significant difference in the time required to reach an INR ≥2.0 between reloading with the usual dose and all other protocols (p < 0.001) without abolishing adverse sequelae. Daily INR testing reduced bleeding complications and INR variations at a significant (p < 0.001) and non-significant level respectively, while timing of restarting showed no significant effect. We found a correlation between INR variations and bleeding complications (odds ratio: 4.65, C.I: 0.59-30.87). 41% of the cohort was discharged on the day their INR turned therapeutic with an average L.o.S of 6.5 days.

CONCLUSION

We recommend to: 1) restart Warfarin at double (or in exceptional cases 1.5 times) the patient's maintenance dose for the first two doses, 2) starting on the Evening of Surgery, 3) with daily INR monitoring after the second loading dose, 4) using point of care testing devices, 5) and dosing thereafter to be guided by an anticoagulation service or computer assistance.

Hospital pharmacist intervention improves the quality indicator of warfarin control: A retrospective cohort study

Background/Aims Our previous study showed that time in therapeutic range (TTR) control of warfarin therapy was negatively affected in non-valvular atrial fibrillation (NVAF) patients with heart failure. This study assesses the effect of intervention by hospital pharmacists on TTR control in Japanese NVAF patients with heart failure. Method This retrospective cohort study included NVAF patients with heart failure admitted and discharged from the cardiovascular internal medicine ward between March 2011 and July 2013. Participants were classified into two groups according to the instructions by hospital pharmacists and physicians (Intervention group) and by physicians only (Usual care group). The primary outcome was TTR. Secondary outcomes were major bleeding and minor bleeding. Results In total, 57 participants (35 males, 22 females; mean age: 69.7 years) were classified into the Intervention (n = 25) and Usual care (n = 32) groups. TTR within-therapeutic range was significantly higher and within sub-therapeutic range was significantly lower in the Intervention than the Usual care group. Major bleeding and minor bleeding were not significantly different between the two groups. Conclusion The intervention of hospital pharmacists with anticoagulation therapy can lead to proper use of warfarin, which can be useful when physicians prescribe warfarin. J. Med. Invest. 64: 266-271, August, 2017.

Effects of vitamin K epoxide reductase complex 1 gene polymorphisms on warfarin control in Japanese patients with left ventricular assist devices (LVAD)

PURPOSE

This study aimed to investigate relationships between times in therapeutic range (TTR) or warfarin sensitivity indexes (WSI) and VKORC1-1639G>A and CYP2C9 polymorphisms in patients with left ventricular assist devices (LVAD).

METHODS

Severe heart failure patients who received LVAD from January 1, 2013 to October 31, 2017 were recruited. Relationships between TTR or WSI and VKORC1-1639G>A and CYP2C9 gene polymorphisms were investigated immediately after LVAD implantation (period 1) and immediately prior to hospital discharge (period 2).

RESULTS

Among 54 patients, 31 (72.1%) had VKORC1-1639AA and CYP2C9*1/*1 (AA group) polymorphisms and 12 (27.9%) had VKORC1-1639GA and CYP2C9*1/*1 (GA group) polymorphisms. During period 1, mean prothrombin time-international normalized ratio (PT-INR) values were significantly higher in the AA group than in the GA group (2.21 vs. 2.05, p < 0.0001). Mean WSI values were 1.68-fold greater in the AA group than in the GA group (1.14 vs. 0.68, p < 0.0001). In addition, times below the therapeutic range (TBTR) in the GA group were significantly greater than in the AA group during period 1 (39.8 vs. 28.3%, p = 0.032), and insufficient PT-INR was more frequent in the GA group than in the AA group. However, mean PT-INR values during period 2 did not differ and no significant differences in TTR, TATR, and TBTR values were identified. In subsequent multivariable logistic regression analyses, the VKORC1-1639GA allele was significantly associated with insufficient anticoagulation.

CONCLUSION

Patients with the VKORC1-1639GA and CYP2C9*1/*1 alleles may receive insufficient anticoagulation therapy during the early stages after implantation of LVAD, and VKORC1-1639G>A and CYP2C9 genotyping may contribute to more appropriate anticoagulant therapy after implantation of LVAD.

Anticoagulation Control in Patients With Ventricular Assist Devices

Anticoagulation control has been associated with risk of thromboembolism and hemorrhage. Herein, we explore the relationship between anticoagulation control achieved in left ventricular assist device (LVAD) patients and evaluate the association with risk of thromboembolism and hemorrhage. Patients (19 years old or older) with a continuous flow LVAD placed from 2006 to 2012. Percent time spent in target range (PTTR) for international normalized ratio (INR) was estimated with target range of 2.0-3.0. Proportion of time spent in target range was categorized into PTTR > 60%, PTTR ≥ 50 < 60%, and PTTR < 50%. The relationship between PTTR and thromboembolism and hemorrhage was assessed. One hundred fifteen participants contributed 624.5 months of follow-up time. Only 20% of patients achieved anticoagulation control (PTTR > 60% for INR range of 2-3). After adjusting for chronic kidney disease, history of diabetes, history of atrial fibrillation, and age at implant, compared with patients with PTTR < 50%, the relative risk of thromboembolism in patients with PTTR ≥ 60% (hazard ratio [HR]: 0.37; 95% confidence interval [CI]: 0.14-0.96; p = 0.042) was significantly lower, but not for patients with a PTTR of ≥ 50 < 60% (HR: 0.21; 95% CI: 0.02-1.82; p = 0.16). The relative risk for hemorrhage was also significantly lower among patients with a PTTR ≥ 60% (HR: 0.45; 95% CI: 0.21-0.98; p = 0.045), but not among those with PTTR of ≥ 50 < 60% (HR: 0.47; 95% CI: 0.14-1.56; p = 0.22). This current study demonstrates that LVAD patients remain in the INR target range an average of 42.9% of the time. To our knowledge, this is the first report with regard to anticoagulation control as assessed by PTTR and its association with thromboembolism, hemorrhage, or death among patients with ventricular assist devices (VADs).

Dedicated warfarin care programme results in superior warfarin control in Queensland, Australia

BACKGROUND

Warfarin is used to prevent stroke in patients with atrial fibrillation (AF). Ongoing monitoring of International normalised ratio (INR) and time in therapeutic range (TTR) commonly used to assess the quality of warfarin management are required. Anticoagulant clinics have demonstrated improved TTRs, particularly in countries with poorer control in primary care settings. Reported TTR in Australia has been relatively high; so, it is unknown if benefit would be seen from dedicated warfarin clinics in Australia. The aim of this study was to compare the level of warfarin control in patients managed by their general practitioner (GP) and a warfarin care programme (WCP) by Sullivan Nicolaides Pathology.

METHOD

Retrospective data were collected for AF patients enrolled in the warfarin care programme at WCP, and included patients with INR tests available while managed by their GP. INR tests were used to calculate TTR and frequency of testing for the time managed by GP and WCP, with mean data used for analysis and comparison.

RESULTS

The eligible 200 warfarin patients had a TTR of 69% with GP management and 82% with WCP management (<.0001). Significant differences were also found between GP and WCP management in the percentage of tests in range, total number of tests and frequency of testing. WCP had a reduced time to repeat test at extremes of INR results.

CONCLUSION

Australian warfarin control was good when managed by either GP or WCP, but WCP management increased TTR by 13%. Dedicated warfarin programmes can improve warfarin control and optimise therapy for patients.

Preoperative coagulation abnormalities as a risk factor for adverse events after pancreas surgery

OBJECTIVE

To determine whether elevated INR or PTT values predicted 30-day postoperative adverse events following elective pancreatectomy.

METHODS

The American college of surgeons national surgical quality improvement program (ACS-NSQIP) database was used to identify 14 747 patients undergoing elective pancreatectomy from 2005 to 2013. The association of elevated INR or PTT with 30-day postoperative outcomes of morbidity and mortality was examined using multivariate logistic regression analysis.

RESULTS

The overall 30-day mortality rate increased from 1.8% to 3.3% from the control to the high INR or PTT group (P = <0.001). An elevated INR/PTT increased the odds for bleeding requiring transfusion, superficial SSI, sepsis, unplanned intubation or >48 h on a ventilator, cardiac arrest or myocardial infarction, acute renal failure, return to the OR, and prolonged length of stay. With the exception of superficial SSI, multivariate logistic regression models revealed that these same events remained statistically significant after controlling for potential confounders.

CONCLUSION

Prolonged bleeding times (high INR/PTT) is associated with increased mortality and adverse outcomes after pancreas surgery. A patient's coagulation profile may serve as a risk stratification tool to identify higher risk patients that require more resources.

Portable coagulometer for vitamin K-antagonist monitoring: the patients' point of view

PURPOSE

The aim of this study was to know the patients' point of view on the monitoring of vitamin K-antagonist (VKA) therapy by means of a point of care testing (POCT), ie, using a portable coagulometer by self-testing at home. At first, patients had prothrombin time (PT) international normalized ratio (INR) monitoring at a thrombosis center; afterward, they were shifted to self-testing at home. An interview was done to evaluate the patients' point of view on the two monitoring periods.

PATIENTS AND METHODS

A total of 92 oral anticoagulated patients were enrolled. The questionnaire contained nine questions that elicited a maximum of five closer answers that were arranged in increasing levels of satisfaction: very little, little, enough, much and completely. Percentage of time in therapeutic range (TTR) and adverse events were compared during the two periods of conventional monitoring and self-testing.

RESULTS

The period of conventional monitoring was shorter than that of self-testing (p<0.0001), and the median TTR was satisfactory but lower than that of self-testing (p<0.0001). A total of 85% of the patients were satisfied with self-testing at home. In all, 83% and 73% (p=0.06) of patients felt comfortable about side effects while measuring the PT INR at both home and the thrombosis center, respectively. During the self-testing period, quality of life was improved in 87% of the patients. The cost of test strips was medium-high for 89% of the patients, and 75% of them stated that it was worth improving their quality of life. A switch from VKA to a direct oral anticoagulant (DOAC) was proposed to 24% of the patients, but 68% of them declined because they felt more comfortable monitoring their oral anticoagulant therapy by POCT.

CONCLUSION

VKA monitoring using POCT at home may play a role in improving the patients' quality of life and may be considered as an alternative to the use of DOAC at least in certain settings of patients.

Reversal of anticoagulant effects of edoxaban, an oral, direct factor Xa inhibitor, with haemostatic agents

Edoxaban, an oral, direct factor Xa inhibitor, has a similar or low incidence of bleeding events compared with other anticoagulants in clinical trials. Therefore, agents to reverse the anticoagulant effects of edoxaban could be desirable in emergency situations. In this study, the reversal effects of haemostatic agents were determined on prothrombin time (PT) prolongation in vitro and bleeding time prolongation in vivo by edoxaban. PT using human plasma was measured in the presence of edoxaban at therapeutic and excess concentrations with the haemostatic agents, prothrombin complex concentrate (PPSB-HT), activated prothrombin complex concentrate (Feiba), and recombinant factor VIIa (rFVIIa). In rats, rFVIIa and Feiba was given during intensive anticoagulation with edoxaban. The haemostatic effect was evaluated in a model of planta template bleeding and a potential prothrombotic effect was evaluated in a venous thrombosis model. PPSB-HT, Feiba, and rFVIIa concentration-dependently shortened PT prolonged by edoxaban. Among these, rFVIIa and Feiba showed potent activities in reversing the PT prolongation by edoxaban. rFVIIa (1 and 3 mg/kg, i.v.) and Feiba (100 U/kg, i.v.) significantly reversed edoxaban (1 mg/kg/h)-induced prolongation of bleeding time in rats. In a rat venous thrombosis model, no potentiation of thrombus formation was observed when the highest dose (3 mg/kg) of rFVIIa was added to edoxaban (0.3 and 1 mg/kg/h) compared with the control. The present study indicated that rFVIIa, Feiba, and PPSB-HT have the potential to be reversal agents for edoxaban.

Comparison of antithrombotic efficacy between edoxaban, a direct factor Xa inhibitor, and fondaparinux, an indirect factor Xa inhibitor under low and high shear rates

Edoxaban is an oral, direct factor Xa (FXa) inhibitor under late-phase clinical development. This study compared the antithrombotic efficacy of edoxaban with that of an indirect FXa inhibitor, fondaparinux, in in vivo venous and arterial thrombosis models and in ex vivo perfusion chamber thrombosis model under low and high shear rates in rats. Venous and arterial thrombi were induced by platinum wire insertion into the inferior vena cava and by application of FeCl3 to the carotid artery, respectively. The perfusion chamber thrombus was formed by blood perfusion into a collagen-coated capillary at 150 s-1 (low shear rate) and 1,600 s-1 (high shear rate). Effective doses of edoxaban that reduced thrombus formation by 50% (ED50) in venous and arterial thrombosis models were 0.076 and 0.093 mg/kg/h, respectively. In contrast, ED50 of fondaparinux in the arterial thrombosis model (>10 mg/kg/h) was markedly higher compared to ED50 in the venous thrombosis model (0.021 mg/kg/h). In the perfusion chamber thrombosis model, the ratio of ED50 under high shear rate (1.13 mg/kg/h) to that under low shear rate (0.63 mg/kg/h) for edoxaban was 1.9, whereas that for fondaparinux was more than 66. While the efficacy of fondaparinux markedly decreased in arterial thrombosis and in a high-shear state, edoxaban exerted consistent antithrombotic effects regardless of flow conditions. These results suggest that shear rate is a key factor in different antithrombotic effects between edoxaban and fondaparinux.

Phytonadione Education Program in a Community Hospital

Purpose

Pharmacists and physicians were educated regarding updated guidelines on phytonadione indications, dosing, and routes of administration. Study objectives were to evaluate the use of phytonadione in a community hospital, educate pharmacists and physicians about phytonadione use, and assess the value of education in terms of patient outcomes.

Methods

Baseline and follow-up data on phytonadione indications, dosages, and routes of administration were collected. Pretests and post-tests were administered before and after an education session. A Pharmacy and Therapeutics newsletter article highlighting the appropriate use of phytonadione was published.

Results

The baseline and follow-up medication use evaluations (MUEs) revealed that 53% and 62% of patients had an appropriate indication for phytonadione, respectively (P = 0.181). Among patients with an appropriate indication, 44% were administered an appropriate dose in the baseline group and 46% in the follow-up (P = 0.876). The baseline MUE revealed that 20% of phytonadione routes of administration were appropriate; 18% were considered appropriate in the follow-up (P = 0.842). Pharmacists' knowledge showed improvement after education efforts, with the mean score improving from 57% to 93.4% from pretest to post-test (P < 0.05) and the median score changing from 50% to 100%.

Conclusion

Improving pharmacists' knowledge is beneficial and necessary; however, it was not enough to change practice in this study. Additional steps must be taken to encourage routine application of the knowledge.

Cost-Effectiveness of Warfarin Medication Therapy Adherence Clinic versus Usual Medical Clinic at Kuala Lumpur Hospital

BACKGROUND

Systematic anticoagulation management clinic is recommended to manage patients on chronic warfarin therapy. In Malaysia, the service was introduced as warfarin medication therapy adherence clinic (WMTAC), which is managed by pharmacists with a physician advisory.

OBJECTIVES

To assess the cost-effectiveness of WMTAC in comparison with usual medical clinic (UMC), which is managed by medical officers in Kuala Lumpur Hospital, a tertiary referral hospital in Malaysia.

METHODS

Data from a 6-month retrospective cohort study comparing the two clinics and the mean percentages of time in the therapeutic range for the patients were used to estimate the cost-effectiveness. The mean clinic costs were estimated using the time-motion study. A Markov model with a 6-monthly cycle was used to simulate lifetime cost-effectiveness from the perspective of the health care service provider. The base-case analysis assumed a cohort of patients with atrial fibrillation, 57 years of age with comorbid illnesses. The transition probabilities of these clinic outcomes were obtained from a literature search. Future costs and effectiveness were discounted by 3% to convert to present values. All costs were in Malaysian ringgit standardized for the year 2007.

RESULTS

The mean 6-month treatment cost was lower for the WMTAC, which was significantly lower (P < 0.001). The UMC was found to be dominated by the WMTAC for both intermediate and lifetime analyses. The sensitivity analysis showed that clinic consultation costs had a major impact on the cost-effectiveness analysis.

CONCLUSIONS

WMTAC is a more cost-effective option than UMC in Kuala Lumpur Hospital.

A High HASBLED Score Identifies Poor Warfarin Control in Patients Treated for Non-Valvular Atrial Fibrillation in Australia and Singapore

Warfarin reduces stroke risk in atrial fibrillation (AF) patients. The quality of warfarin control, measured by time in therapeutic range (TTR), impacts outcome and adverse events. One tool evaluating risk of adverse events and potential warfarin control would simplify risk-benefit assessment of warfarin. Recently, HASBLED was demonstrated effective for this purpose, but this was in well-controlled patients with deep vein thrombosis. HASBLED as a predictor of warfarin control has not been validated in other populations including differing indications, warfarin control levels and ethnicities. The aim of this study was to determine whether HASBLED can predict warfarin control in patients with AF in Australia and Singapore. Retrospective data were collected for patients receiving warfarin between January and June 2014 in Australia and Singapore. Patient data were used to calculate HASBLED at the start and end of the study period. TTR was calculated for each patient, and mean TTR used for analysis to stratified HASBLED scores. Of the 4370 patients, there were 3199 in Australia and 1171 in Singapore with mean TTRs of 82% and 58%, respectively. At the start of the study, a HASBLED score ≥3 predicted significantly lower TTR in Singapore, whilst at the end of the study, this score identified patients with poor control in both Australia and Singapore. A HASBLED score ≥3 in patients treated with warfarin can differentiate significantly lower TTRs in Australian and Singapore patients with AF. HASBLED may assess bleed risk and warfarin control, identifying patients at high risk of poor warfarin outcome requiring additional INR monitoring or alternative anticoagulation.

Thoracoscopic Ablation With Appendage Ligation Versus Medical Therapy for Stroke Prevention: A Proof-of-Concept Randomized Trial

OBJECTIVE

Atrial fibrillation (AF) has a demonstrable effect on quality of life (QOL). Recurrent stroke occurs in 10% of patients with AF. The objective of this study was to demonstrate proof of concept that thoracoscopic pulmonary vein isolation and atrial appendage ligation (TPVIAL) could prevent recurrent stroke and could potentially improve QOL in patients with AF with a previous stroke.

METHODS

The study was a National Institutes of Health-funded single-center proof-of-concept design that randomized 23 patients with AF-related stroke to TPVIAL (n = 12) or to medical management (n = 11). Quality of life was the primary outcome variable; secondary end points included restoration of rhythm, recurrent stroke, and surgical morbidity.

RESULTS

Quality-of-life subscores at 3 and 6 months revealed improvements in energy and decreases in fatigue in the TPVIAL arm [baseline, 33 (19.8); 3 months, 49.5 (20.6), P = 0.01; 6 months, 55.5 (14.4), P = 0.03]. At 12-month follow-up, there were no recurrent strokes in the TPVIAL group. In the medically treated arm, two patients at 6 months (P = 0.22) and three total patients at 12 months (P = 0.09) had recurrent ischemic stroke. There was one death in the medical management arm. In the TPVIAL arm, no AF recurrence occurred in patients with paroxysmal AF, and one patient had recurrence of persistent and long-standing AF. Seven patients in the TPVIAL arm discontinued warfarin therapy for secondary stroke prevention.

CONCLUSIONS

This small proof-of-concept study showed that TPVIAL improved QOL on two subscores and restored normal sinus rhythm in all but one patient, and it showed the potential to prevent secondary stroke. A larger study will be needed.

Anticoagulation Monitoring Part 1: Warfarin and Parenteral Direct Thrombin Inhibitors

OBJECTIVE:

To review the availability, mechanisms, limitations, and clinical application of point-of-care (POC) devices used in the management of warfarin and parenteral direct thrombin inhibitors.

DATA SOURCES:

Scientific articles were identified through a MEDLINE search (1966–August 2004), manufacturer Web sites, additional references listed in articles and Web sites, and abstracts from scientific meetings.

STUDY SELECTION AND DATA EXTRACTION:

English-language literature from clinical trials was reviewed to evaluate the accuracy, reliability, and clinical application of POC monitoring devices.

DATA SYNTHESIS:

The prothrombin time expressed as the international normalized ratio (PT—INR) is a well-established test for monitoring warfarin anticoagulation. Multiple devices are available for POC testing. Because there is no universally accepted standard, the performance of each device is typically tested against a standard test performed in a reference laboratory. Performance of currently available devices, as measured by correlations to a standard reference laboratory PT—INR, may be considered very good and acceptable for use in patient care. Utilization of patient self-testing and patient self-monitoring of warfarin anticoagulation using POC devices is increasing. Parenteral direct thrombin inhibitors are typically monitored using a standard laboratory activated partial thromboplastin time. Some research has shown that POC monitoring of direct thrombin inhibitors using the ecarin clotting time is helpful for patients undergoing cardiopulmonary bypass surgery, although that test is not readily available.

CONCLUSIONS:

POC testing for anticoagulation therapy has been available for >20 years. Multiple POC devices are available to monitor warfarin. There is some variability in results between devices and between reagents used in the same device. Despite these limitations, POC monitoring of warfarin via the PT—INR is an integral part of clinical practice. Additional research evaluating POC monitoring of direct thrombin inhibitors is necessary.

Quality of Anticoagulation Monitoring in Nonvalvular Atrial Fibrillation Patients: Comparison of Anticoagulation Clinic versus Usual Care

Background:

Prior research suggests that receiving specialized anticoagulation services enables patients to achieve better clinical outcomes.

Objective:

To assess the quality of anticoagulation therapy in patents with atrial fibrillation who were enrolled in an anticoagulation clinic (ACC) versus usual care (UC).

Methods:

Using Sharp Rees-Stealy physician group claims data, we estimated time spent in therapeutic range and time to first major bleeding episode or stroke for ACC and UC patients. t-Tests were used to compare time h therapeutic range proportions, and Kaplan-Meier survival analysis was performed to compare rates of bleeding and stroke between groups.

Results:

We identified 1107 patients (351 ACC, 756 UC) treated with anticoagulation therapy for atrial fibrillation with more than one international normalized ratio (INR) reported between March 2001 and March 2004. ACC patients spent a greater proportion (68.14%) of time in therapeutic range compared with UC patients (42.07%; p < 0.001). There was a significant difference between groups in average time between INR tests (ACC = 14.31 days, UC = 18.39 days; p < 0.001). ACC patients were 59% less likely to experience a bleed following the index date than were UC patients (HR = 0.41; 95% CI 0.2444 to 0.6999; p = 0.001), but type of care was not a significant predictor for stroke (HR = 0.95; 95% CI 0.5125 to 1.7777; p value NS).

Conclusions:

Results from this observational study reinforce the positive impact that anticoagulation services have on anticoagulation therapy outcomes, emphasizing the importance of providing such services for patients undergoing treatment with warfarin.

Development and Validation of an Instrument to Determine Patient Knowledge: The Oral Anticoagulation Knowledge Test

Background:

Studies examining the relationship between patient knowledge regarding warfarin therapy and its safe and effective use are limited by the lack of validated knowledge assessment tools.

Objective:

To develop and validate an instrument to assess patient knowledge regarding oral anticoagulation therapy.

Methods:

Four nationally recognized anticoagulation experts participated in the instrument development process to ensure content validity. The Oral Anticoagulation Knowledge (OAK) test was administered to subjects on warfarin and a group of age-matched subjects not on warfarin to assess construct validity. A subgroup of warfarin subjects were retested approximately 2–3 months after initial testing to assess test–retest reliability. Internal consistency reliability was assessed by calculating a Kuder-Richardson 20 value. Item analysis was used to assess performance of individual questions.

Results:

An initial 23 item instrument was pilot tested for readability and comprehension. The OAK test was administered to 74 subjects taking warfarin and 27 age-matched subjects not on warfarin. Thirty-two subjects on warfarin repeated the OAK test an average of 75 days following initial administration. Subjects taking warfarin scored significantly higher than those not on warfarin (72% vs 52%, respectively; p < 0.001), supporting the construct validity of the instrument. Test–retest reliability was acceptable, with a Pearson's correlation coefficient of 0.81. Internal consistency reliability was confirmed by a calculated Kuder–Richardson 20 value of 0.76.

Conclusions:

The OAK test is a brief, valid, and reliable knowledge assessment instrument that may be a useful tool for research and clinical practice to augment patient education programs.