Time in Therapeutic Range and Percentage of International Normalized Ratio in the Therapeutic Range as a Measure of Quality of Anticoagulation Control in Patients With Atrial Fibrillation

Comparison of anticoagulation control and outcomes between usual medical care and pharmacist-led anticoagulation service in ambulatory patients taking warfarin at tertiary hospital in Ethiopia: a quasi-experimental study

BACKGROUND

We aimed to compare anticoagulation control and outcomes between usual medical care (UMC) and pharmacist-led anticoagulation services (PLAS) in patients receiving warfarin at the Tikur Anbessa Specialized Hospital (TASH), Addis Ababa, Ethiopia.

METHODS

A quasi-experimental study was conducted, including 350 (66.7%) and 175 (33.3%) patients from the UMC and PLAS groups, respectively, from 525 patients. The time in therapeutic range (TTR) was determined using the Rosendaal method, with a TTR ≥ 65% set as the cut-off for optimal anticoagulation. The two-sample Wilcoxon rank-sum (Mann-Whitney U) test was used to compare continuous variables between groups. Categorical variables were compared between groups using Pearson's chi-square test or Fisher's exact test. Logistic regression and negative binomial regression analyses were conducted to identify the factors associated with suboptimal TTR and secondary outcomes, respectively, at the p values < 0.05, and 95% confidence interval (CI).

RESULTS

Compared with the UMC group, the patients in the PLAC group showed a significantly higher median (IQR) TTR [60.89% (43.5-74.69%) vs. 53.65% (33.92-69.14%), p < 0.001]. A significantly higher optimal TTR (≥ 65%) was achieved in the PLAC group (41.7% vs. 31.7%) than in the UMC group (p = 0.002). The odds of having a poor TTR were reduced by 43% (AOR = 0.57, 95% CI = 0.36-0.88, p = 0.01) among patients in the PLAC group compared to those in the UMC group. There were no statistically significant differences in the secondary outcomes between the groups, except for all-cause emergency visits (p = 0.003). The incidence of bleeding events decreased by 3% (IRR = 0.97, 95% CI = 0.96-0.99, p < 0.001) for every increase in INR monitoring frequency. The incidence of thromboembolic events increased by a factor of 15.13 (IRR = 15.13, 95% CI = 1.47-155.52, p = 0.02) among patients with a high-risk CHA2DS2-VASc score compared with those with a moderate score.

CONCLUSION

Patients in the PLAC group had a significantly higher median TTR than those in the UMC group did. There were no statistically significant differences in the secondary outcomes between the groups, except for fewer all-cause emergency department visits in the PLAC group.

A regional anticoagulation program improves safety and outcomes for both children and adults

BACKGROUND

Evidence-based anticoagulation programs usually serve a local, adult patient population. Here we report outcomes for a regional combined pediatric-adult program.

AIMS

The aims of this study were: (1) Compare the pre- vs. post-implementation quality of therapy (% time in therapeutic range (%TTR) and compliance). (2) Assess anticoagulant-relevant outcomes (bleeding and thrombotic complications).

METHODS

Data were collected for the years 2014-2019. Rosendaal linear interpolation was used to calculate %TTR. Bleeding complications were categorized using ISTH-SSC standard nomenclature and new thrombotic events were reviewed.

RESULTS

The patients were divided into a long-term warfarin group (N = 308), 80.2% of whom had cardiac-related therapeutic indications (median age 24y), and a second group (N = 114) comprised of short-term and non-warfarin long-term anticoagulation (median age 16y). Median %TTR for those on long-term warfarin was 78.9%. The incidence of major and clinically relevant non-major bleeding events was 1.65 and 2.43 /100 person-years of warfarin use, respectively. Thromboembolism (TE) incidence was 0.78/100 patient-years of warfarin use. Neither bleeding nor thrombosis was associated with %TTR (p = 0.48). Anticoagulant indication was the only variable associated with bleeding risk (p = 0.005). The second group had no on-therapy TE events but 7.9% experienced bleeding. Complete data were available for a randomly sampled pre-program warfarin group (N = 26). Median %TTR improved from 17.5 to 87% pre- vs. post-implementation. Similarly, compliance (defined as ≥ 1 INR/month) improved by 34.3%.

CONCLUSIONS

In conclusion, this program significantly improved and sustained %TTR and compliance. The lack of association between bleeding and thrombosis events and %TTR may be related to the high median %TTR (> 70%) achieved by this approach.

Anticoagulation Management in Patients Receiving Warfarin at Private Cardiac Centers in Addis Ababa, Ethiopia

Introduction

Anticoagulants are the cornerstone therapy for thromboembolism prevention and treatment. Warfarin is the frequently prescribed drug and remains the oral anticoagulant of choice in low- and middle-income countries, including Ethiopia. It is a narrow therapeutic index drug that needs high-quality anticoagulation monitoring with frequent international normalization ratio (INR) testing.

Objective

The study aimed to assess anticoagulation management with warfarin among adult outpatients at two selected private cardiac centers in Addis Ababa, Ethiopia.

Methods

A hospital-based retrospective study design that enrolled 374 patients receiving warfarin was employed at two private cardiac centres in Addis Ababa, Ethiopia. The time in the therapeutic range (TTR) was calculated using the Rosendaal method. The data were analyzed using Statistical Package for Social Science version 25.

Results

The mean age of the patients was 57 years, and 218 (58.3%) participants were females. Out of 3384 INR tests, 1562 (46.5%) were within the therapeutic range and the mean percentage of TTR was 47.24%. Only 25.67% of the patients spent their TTR ≥ 65%. The present study revealed that dose adjustments were required 1764 times. In non-therapeutic INR values of 1764 that required warfarin dose adjustment, 59.7% of the doses were adjusted. About 262 (70.1%) of co-prescribed medications had interaction with warfarin. Sixty-four patients (17.11%) experienced bleeding events.

Conclusion

Anticoagulation management with warfarin was suboptimal in private cardiac Addis Ababa, Ethiopia, private cardiac centers. Warfarin adjustment practice for nontherapeutic INR values was not minimal, and many patients encountered bleeding during their course of therapy.

Anticoagulation control, outcomes, and associated factors in long-term-care patients receiving warfarin in Africa: a systematic review

Background

Oral anticoagulation therapy with warfarin requires frequent monitoring level of anticoagulation by the international normalized ratio (INR). In Africa, studies that explore anticoagulation control, treatment outcomes, and associated factors are reported in various ways in long-term patients receiving warfarin therapy to generate concrete scientific evidence.

Methods

The literature search was conducted in PubMed, Cochrane Library, African Journal of Online databases, Google Scholar, and Google. An advanced search strategy was computed to retrieve relevant studies related to anticoagulation control and outcomes. Duplication, title and abstract screening, and full-text assessment were conducted in Covidence software. Study quality was assessed using the Joanna Briggs Institute Critical appraisal quality assessment tool. The systematic review is registered in PROSPERO (CRD42021260772) and performed based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guideline.

Results

Out of 298 identified articles, 18 articles were eligible for the final review and analysis. The mean of 39.4 ± 8.4% time in therapeutic range (TTR) (29.4 to 57.3%), 36.7 ± 11.5% TTR (range 25.2–49.7%) and 46% TTR (43.5–48.5%) was computed from studies that determined TTR by Rosendaal, direct and cross-section-of-the-files methods, respectively. In this review, the lowest percentage of TTR was 13.7%, while the highest was 57.3%. The highest percentage of patients (32.25%) who had TTR ≥ 65% was reported in Tunisia, but the lowest percentages were in Namibia (10%, TTR ≥ 65%) and Kenya (10.4%, TTR ≥ 70%). Most of the included studies (11 out of 18) used Rosendaal’s method while the direct method was employed by three studies. Generally, 10.4–32.3% of study participants achieved desired optimal anticoagulation level. Regarding secondary outcomes, 1.6–7.5% and 0.006–59% of patients experienced thromboembolic complications and bleeding events, respectively. Having chronic comorbidities, taking more than two drugs, and presence of medications that potentially interact with warfarin, and patient-related factors (patients aged < 50 years old, female gender, lower education level, smoking history) were the frequently reported predictors of poor anticoagulation therapy.

Conclusions

Oral anticoagulation control was suboptimal in patients taking warfarin as evidenced by low TTR in Africa. Therefore, there is an urgent need for further improving oral anticoagulation management services.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-022-00416-9.

Protocol for Home-Based Solution for Remote Atrial Fibrillation Screening to Prevent Recurrence Stroke (HUA-TUO AF Trial): a randomised controlled trial

INTRODUCTION

Current international guidelines recommend ECG monitoring after an ischaemic stroke to detect atrial fibrillation (AF) in order to prevent stroke recurrence. However, optimal strategies to detect AF and the downstream management to prevent stroke recurrence remain to be established. The objective of the study was to explore the use of long-term home-based ECG monitoring for AF detection and stroke prevention in patients with a history of stroke.

METHODS AND ANALYSIS

This prospective, randomised, open-label trial with blinded endpoint adjudication aimed to evaluate the efficacy of long-term home-based ECG monitoring for AF detection and stroke prevention in a 24-month period. Patients aged >18 years with a history of ischaemic stroke will be stratified according to the time from the index ischaemic stroke: <1, 1-3 and >3 years and then randomised in 1:1 to (1) home-based AF screening and (2) control. The home-based AF screening system comprises (1) a handheld single-lead ECG recorder (Comfit Healthcare Devices, Hong Kong SAR, China) and (2) a patient-facing smartphone application specially designed for the study. Patients randomised to the home-based AF group will record a 30 s single-lead ECG using a specially designed handheld ECG device every morning or when symptomatic. All remotely obtained data will be automatically transmitted in real-time through the study smartphone application to a secured cloud hosting and analysed using an artificial intelligence-based diagnostic system. When a diagnosis of AF is made with the system, the patients will be called back for a formal cardiology consultation within 1 week. The primary endpoint is the time to first detection of AF at 24 months of follow-up. Secondary endpoints include recurrent stroke or transient ischaemic attack, initiation of long-term anticoagulation therapy, hospitalisation for heart failure, cardiovascular death and all-cause death.

ETHICS AND DISSEMINATION

The study protocol has been approved by the institutional review board of The University of Hong Kong, and Hong Kong West Cluster, Hospital Authority, Hong Kong SAR, China. Results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04523649.

Comparison of frequency of silent cerebral infarction as assessed by serum neuron specific enolase in patients with non-valvular atrial fibrillation: Warfarin versus direct oral anticoagulant

BACKGROUND

Cerebral infarction in patients with atrial fibrillation (AF) may clinically vary from being silent to catastrophic. Silent cerebral infarction (SCI) is the neuronal injury in the absence of clinically appearent stroke or transient ischaemic attack. Serum neuron specific enolase (NSE) is suggested to be a valid surrogate biomarker that allows to detect recent neuronal injury. We aimed to evaluate the incidence of recent SCI by positive NSE levels in patients with non-valvular AF (NVAF) on oral anticoagulants.

METHODS

Blood samples for NSE were collected from 197 consecutive NVAF patients. NSE levels of greater than 12 ng/ml was considered as positive and suggestive of SCI.

RESULTS

Patients were mainly female with a mean age of 69 years. Ninety-eight of them (49.7%) were taking warfarin. Mean INR level was 2.3 ± 0.9. Mean CHA₂DS₂-VASc score of the study population was 3.5 ± 1.5. Seventy-two patients (36.5%) were found to have NSE elevation. They were more likely to have history of chronic heart failure and previous stroke/TIA. Increased left atrial diameter and higher CHA₂DS₂-VASc were other factors associated with SCI. Patients on DOACs and patients taking aspirin on top of oral anticoagulant treatment were less likely to have SCI. Multivariate analysis demonstrated that increased left atrial diameter (OR: 2.5; 95% CI: 1.52-4; p < 0.001) and use of warfarin (OR: 2.8; 95% CI: 1.37-5.61; p = 0.005) were detected as independent predictors of SCI.

CONCLUSIONS

Our study revealed that DOACs were associated with significantly reduced SCIs compared with warfarin, probably due to more effective and consistent therapeutic level of anticoagulation.

Relation of the 'Atrial Fibrillation Better Care (ABC) Pathway' to the Quality of Anticoagulation in Atrial Fibrillation Patients Taking Vitamin K Antagonists

The Atrial Fibrillation Better Care (ABC) pathway was proposed for a more integrated atrial fibrillation (AF) care. We investigated if adherence to the ABC pathway was associated to the quality of anticoagulation control in a cohort of AF outpatients starting vitamin K antagonists (VKAs) between July 2016 and June 2018. Patients were considered adherent to the ABC pathway if they met all of its components. The time in therapeutic range (TTR) was estimated at one year. In total, 1045 patients (51.6% female; median age 77 years; 63% ABC pathway adherent) were included. At one year, 474 (51.6%) of 919 patients with international normalized ratio (INR) data for TTR estimation had a TTR < 65%. Among ABC pathway non-adherent patients, a greater proportion had TRT < 65% (56.4% vs. 43.6%, p = 0.025), and TTR < 70% (64.9% vs. 35.1%, p = 0.033), with lower mean TTR in non-adherent patients (59.4 ± 22.3% vs. 63.9 ± 21.1%; p = 0.004). Logistic regression models demonstrated that the ABC pathway adherence in its continuous (aOR: 0.75, 95% CI 0.59−0.96) and categorical (aOR: 0.75, 95% CI 0.57−0.98) forms was independently associated with TTR ≥ 65%. In this ‘real-world’ cohort of AF patients starting VKAs, the ABC pathway adherent patients had better TTR, and more ABC criteria fulfilled increased the probability of achieving good TTR.

Anticoagulation Control, Outcomes, and Associated Factors in Patients with Atrial Fibrillation Receiving Warfarin at Tertiary Care Hospital in Ethiopia

Anticoagulation is the cornerstone in the prevention of stroke in atrial fibrillation. This study aimed at assessing the anticoagulation control and outcome and predictive factors in atrial fibrillation patients on warfarin therapy. A retrospective chart review was used to evaluate patients with atrial fibrillation who were on warfarin during two years follow up at the anticoagulation clinic of the hospital. The time in therapeutic range (TTR) was calculated using Rosendaal's method. Data were analyzed using SPSS software version 25. Univariable and multivariable analyses were computed to determine factors affecting TTR and bleeding events. We included 300 patients in this study. The mean percentage TTR was 42.03 ± 18.75. Only 38 (12.67%) patients achieved a TTR of above 65%. The average international normalized ratio (INR) testing frequency was 35 days (16.3-67.2 days). Taking 1 or 2 drugs along with warfarin was found to be better in achieving good TTR as compared to taking more than two drugs (p = .014). Having heart failure was associated with a 2.45 times odds of poor anticoagulation control (TTR< 65%) (p = .047). Male study participants were 2.53 times more likely of developing bleeding events than females (p = .009). Bleeding events were observed in 62 (20.67%) patients. Study participants, who didn't have Diabetic Mellitus and those not receiving aspirin were at lower odds developing bleeding events (AOR = .196; C.I. = .060-.638; p−.007 and AOR = .099; CI. = .024-.416; p−.02), respectively. In summary, the time spent in the therapeutic range was minimal in this population of patients with AF on warfarin managed at a hospital run anticoagulation clinic in Ethiopia. Moreover, the number of co-prescribed medications, and having heart failure were associated with poor TTR. Bleeding events were high and affected by male sex, having DM comorbidity, and using aspirin.

The Risk of Acute Kidney Injury with Oral Anticoagulants in Elderly Adults with Atrial Fibrillation

BACKGROUND AND OBJECTIVES

Anticoagulation with either a vitamin K antagonist or a direct oral anticoagulant may be associated with AKI. Our objective was to assess the risk of AKI among elderly individuals with atrial fibrillation newly prescribed a direct oral anticoagulant (dabigatran, rivaroxaban, or apixaban) versus warfarin.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our population-based cohort study included 20,683 outpatients in Ontario, Canada, ≥66 years with atrial fibrillation who were prescribed warfarin, dabigatran, rivaroxaban, or apixaban between 2009 and 2017. Inverse probability of treatment weighting on the basis of derived propensity scores for the treatment with each direct oral anticoagulant was used to balance baseline characteristics among patients receiving each of the three direct oral anticoagulants compared with warfarin. Cox proportional hazards regression was performed in the weighted population to compare the association between the prescribed anticoagulant and the outcomes of interest. The exposure was an outpatient prescription of warfarin or one of the direct oral anticoagulants. The primary outcome was a hospital encounter with AKI, defined using Kidney Disease Improving Global Outcomes thresholds. Prespecified subgroup analyses were conducted by eGFR category and by the percentage of international normalized ratio measurements in range, a validated marker of anticoagulation control.

RESULTS

Each direct oral anticoagulant was associated with a significantly lower risk of AKI compared with warfarin (weighted hazard ratio, 0.65; 95% confidence interval, 0.53 to 0.80 for dabigatran; weighted hazard ratio, 0.85; 95% confidence interval, 0.73 to 0.98 for rivaroxaban; and weighted hazard ratio, 0.81; 95% confidence interval, 0.72 to 0.93 for apixaban). In the subgroup analysis, the lower risk of AKI associated with each direct oral anticoagulant was consistent across each eGFR strata. The risk of AKI was significantly lower among users of each of the direct oral anticoagulants compared with warfarin users who had a percentage of international normalized ratio measurements ≤56%.

CONCLUSIONS

Direct oral anticoagulants were associated with a lower risk of AKI compared with warfarin.

Does Warfarin or Rivaroxaban at Low Anticoagulation Intensity Provide a Survival Benefit to Asian Patients With Atrial Fibrillation?

Background: Low-dose rivaroxaban and low-intensity warfarin are widely used in Asia for patients with atrial fibrillation (AF). However, in Asians, it is unclear whether low-dose rivaroxaban and low-intensity warfarin can improve the prognosis of AF. In this study, we investigate the survival benefits of low-dose rivaroxaban and low-intensity warfarin in Asian patients with AF in clinical practice. Methods: This cohort study used medical records in a single tertiary hospital in China, between 2019 and 2020, to identify patients with AF who used rivaroxaban or warfarin, or had no anticoagulant therapy. Follow-ups were performed through telephone contact or medical record review. Cox proportional hazards models were used to compare the risk of mortality of patients in the anticoagulant-untreated group vs. warfarin-treated groups and rivaroxaban-treated groups. Results: A total of 1727 AF patients, discharged between 2019 and 2020, were enrolled in this cohort, of which 873 patients did not use any anticoagulant, 457 patients received warfarin and 397 patients used rivaroxaban. Multivariable analysis showed that, of all the warfarin groups, patients with an international normalized ratio (INR) below 2, good INR control, or poor INR control had a significantly lower risk of mortality compared with that of patients without anticoagulants (HR 0.309, p = 0.0001; HR 0.387, p = 0.0238; HR 0.363, p < 0.0001). Multivariable Cox proportional hazard analyses also demonstrated that, compared with the no anticoagulant group, all rivaroxaban dosage groups (≤10 mg, HR 0.456, p = 0.0129; 15 mg, HR 0.246, p = 0.0003; 20 mg, HR 0.264, p = 0.0237) were significantly associated with a lower risk of mortality. Conclusion: Despite effects being smaller than observed with recommended optimal anticoagulation, the use of warfarin with an INR below 2, poor INR control and the use of low-dose rivaroxaban may still provide survival benefits, suggesting viable alternatives that enable physicians to better resolve decisional conflicts concerning the risks and benefits of anticoagulant therapies, as well as for patients in need of but unable to receive standard anticoagulant therapy due to bleeding risk or other factors, such as financial burden, concerns of adverse outcomes, as well as low treatment compliance and persistence.

Antithrombotic therapy and the risk of new-onset dementia in elderly patients with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is associated with an increased risk of dementia. Little is known about the relationship of antithrombotic therapy and the risk of dementia in patients with AF without clinical stroke.

METHOD

This was an observational study based on a hospital AF registry. Patients aged 65-85 years at the time of AF diagnosis were identified via the computerised database of the clinical management system. Patients with prior stroke or known cognitive dysfunction were excluded. The primary outcome was newly diagnosed dementia during the follow-up period.

RESULTS

3284 patients (mean age 76.4±5.3 years, 51.6% male) were included for analysis. The mean CHA₂DS₂-VASc score was 3.94±1.44. 18.5% patients were prescribed warfarin, 39.8% were prescribed aspirin and 41.7% were prescribed no antithrombotic therapy. After a mean follow-up of 3.6 years, 71 patients (2.2%) developed dementia, giving rise to an incidence of 0.61%/year. The incidence of dementia were 1.04%/year, 0.69%/year and 0.14%/year for patients on no therapy, aspirin and warfarin, respectively. Both univariate and multivariate analyses showed that age ≥75 years, female gender and high CHA₂DS₂-VASc score were associated with significantly higher risk of dementia; warfarin use was associated with significantly lower risk of dementia (HR: 0.14%, 95% CI 0.05 to 0.36, p<0.001). Patients on warfarin with time in therapeutic range (TTR) ≥65% had a non-significant trend towards a lower risk of dementia compared with those with TTR <65%.

CONCLUSION

In elderly AF patients, warfarin therapy was associated with a significantly lower risk of new-onset dementia compared those with no therapy or aspirin.

Time in therapeutic range, quality of life and treatment satisfaction of patients on long-term warfarin for non-valvular atrial fibrillation: a cross-sectional study

BACKGROUND

The use of warfarin in patients with non-valvular atrial fibrillation (NVAF) can be challenging. In this study, we evaluate the time in therapeutic range (TTR), health-related quality of life (HRQoL) and treatment satisfaction of patients on long-term warfarin for NVAF. The HRQoL and treatment satisfaction were compared based on the TTR.

METHODS

A cross-sectional study was conducted among patients on warfarin for NVAF who attended the anticoagulant clinic of a tertiary cardiology referral center in Sarawak from 1st June 2018 to 31st May 2019. Patients' TTR was calculated by using Rosendaal technique, while their HRQoL and treatment satisfaction were assessed by using Short Form 12 Health Survey version 2 (SF12v2) and Duke Anticoagulant Satisfaction Scale (DASS), respectively.

RESULTS

A total of 300 patients were included, with mean TTR score of 47.0 ± 17.3%. The physical component summary (PCS) and mental component summary (MCS) score of SF-12v2 were 47.0 ± 9.0 and 53.5 ± 9.6, respectively. The total score for DASS was 55.2 ± 21.3, while the score for limitations (L), hassles and burdens (H&B) and positive psychological impacts (PPI) were 18.0 ± 10.0, 15.6 ± 9.1 and 21.6 ± 5.9, respectively. Seventy-three (24.3%) patients had good TTR (≥ 60%), with mean of 70.2 ± 8.7%; while 227 (75.5%) patients with poor TTR had significantly lower mean of 39.5 ± 11.9% (p = 0.006). There was no significant difference in the score of PCS (p = 0.150), MCS (p = 0.919) and each domain of SF-12v2 (p = 0.184-0.684) between good and poor TTR, except for social functioning (p = 0.019). The total DASS score was also not significantly different between group (p = 0.779). Similar non-significant difference was also reported in all the DASS sub dimensions (p = 0.502-0.699).

CONCLUSIONS

Majority of the patients on long-term warfarin for NVAF in the current study have poor TTR. Their HRQoL and treatment satisfaction are independent of their TTR. Achieving a good TTR do not compromise the HRQoL and treatment satisfaction. Therefore, appropriate measures should be taken to optimise INR control, failing which direct oral anticoagulant therapy should be considered.

Protocol, rationale and design of DAbigatran for Stroke PreVention In Atrial Fibrillation in MoDerate or Severe Mitral Stenosis (DAVID-MS): a randomised, open-label study

INTRODUCTION

Current international guidelines recommend non-vitamin K oral anticoagulants (NOACs) for stroke prevention among patients with non-valvular atrial fibrillation (AF) at significant ischaemic stroke risk given the superior safety and comparable efficacy of NOACs over warfarin. Nonetheless, the safety and effectiveness of NOACs have not been evaluated in patients with AF with underlying moderate or severe mitral stenosis (MS), hence the recommended stroke prevention strategy remains warfarin therapy.

METHOD AND ANALYSIS

MS remains disproportionately prevalent in Asian countries compared with the developed countries. This prospective, randomised, open-label trial with blinded endpoint adjudication aims to evaluate the safety and efficacy of dabigatran for stroke prevention in AF patients with moderate or severe MS. Patients with AF aged ≥18 years with moderate or severe MS not planned for valvular intervention in the coming 12 months will be randomised in a 1:1 ratio to receive dabigatran 110 mg or 150 mg two times per day or warfarin with international normalised ratio 2-3 in an open-label design. Patients with estimated creatinine clearance <30 mL/min, or with a concomitant indication for antiplatelet therapy will be excluded. The primary outcome is a composite of stroke and systemic embolism. Secondary outcomes are ischaemic stroke, systemic embolism, haemorrhagic stroke, intracranial haemorrhage, major bleeding and death. The estimated required sample size is approximately 686 participants.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Institutional Review Board of the University of Hong Kong and Hong Kong West Cluster, Hospital Authority, Hong Kong for Fung Yiu King Hospital, Grantham Hospital, Queen Mary Hospital and Tung Wah Hospital in Hong Kong. Results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT04045093); pre-results.

Discrepancy Among Self-Reported Adherence, Prescription Refills, and Actual Anticoagulant Control

BACKGROUND

Patients must adhere to their prescribed warfarin regimens and regularly monitor the anticoagulation effect to maintain therapeutic levels. The ability to evaluate regimen adherence accurately is crucial to the success of patient coaching. However, prevention of thromboembolic events is challenging when the association between medication adherence and the actual amount of anticoagulant agent taken cannot be determined.

PURPOSE

This study used self-reported medication taken and prescription refills to (a) verify warfarin medication adherence and (b) assist clinicians to determine the discrepancy between medication adherence and anticoagulant control efficacy.

METHODS

This study was conducted at a national-university-affiliated hospital in Yilan County, Taiwan. Structured questionnaires and medical record reviews were adopted. A 100-point visual analog scale was used to measure the reported adherence of participants, whereas medication refill adherence was compared against self-reported adherence. Finally, degree of adherence was evaluated based on time in therapeutic range.

RESULTS

This study included 192 participants. Half (n = 94, 49%) were women, and the mean age was 69.6 years. Mean scores were 92.2% for the visual analog scale and 87.3% for medication refill adherence. Medication adherence correlated significantly with age, as reflected in the visual analog scale scores (p < .05). The participants who were receiving polypharmacy with five types of medicines or less attained higher visual analog scale scores, whereas participants who were on warfarin for 2-12 months exhibited higher medication refill adherence. Time in therapeutic range correlated negatively with age, although stability improved with therapy duration.

CONCLUSIONS/IMPLICATIONS FOR PRACTICE

Despite their high self-reported adherence levels, patients of advanced age require careful monitoring of their time in therapeutic range. The participants in this study who were on warfarin for a relatively longer time exhibited higher stability in the therapeutic range, despite their low medication refill adherence. The results of this study suggest that patient age, duration of warfarin therapy, and polypharmacy are factors associated with medication adherence. The findings may facilitate future assessments of warfarin adherence in patients as well as the implementation of more effective clinical nursing procedures and management practices.

Relationship between silent cerebral infarcts and quality of anticoagulation in patients with prosthetic mitral valves

OBJECTIVE

Although patients with prosthetic heart valves have an increased risk of clinically overt cerebrovascular events, evidence for the risk of silent cerebral infarction (SCI) is scarce. Serum neuron-specific enolase (NSE) is suggested to be a valid biomarker that allows for the quantification of the degree of neuronal injury. We aimed to assess whether NSE is elevated as a marker of recent SCI in patients with a prosthetic mitral valve.

METHODS

We measured the NSE levels in 103 patients with a prosthetic mitral valve (PMV), admitted to our outpatient clinics for routine evaluation. International normalized ratio (INR) and time in target therapeutic range (TTR) were noted as anticoagulation quality measures.

RESULTS

Most of the patients were females (58%), and a mean age was 65 years. NSE values of >12 ng/mL, suggesting a recent SCI, was detected in 25 patients (24%). NSE was negatively correlated with admission INR (r=-0.307, p=0.002). Multivariate analyses demonstrated subtherapeutic INR (INR <2.5) and suboptimal TTR as independent predictors of SCI [odds ratio (OR) 5.420; 95% confidence interval (CI) 1.589 to 18.483; p=0.007, and OR 4.149; 95% CI 1.019 to 16.949; p=0.047, respectively]. Being a current smoker (OR 10.798; 95% CI 2.520 to 46.272; p=0.001), large left atrium (OR 6.763; 95% CI 2.253 to 20.302; p=0.001), and not using aspirin (OR 10.526; 95% CI 1.298 to 83.333; p=0.027) were other independent predictors.

CONCLUSION

Our data suggest that silent brain infarcts are very prevalent among patients with a PMV, as one fourth of them had the event during their routine outpatient visit. Poor quality of anticoagulation partly explains the increased prevalence.

Relation of quality of anticoagulation control with different management systems among patients with atrial fibrillation: Data from FANTASIIA Registry

BACKGROUND

Anticoagulation control in patients with atrial fibrillation (AF) has a multidisciplinary approach although is usually managed by general practitioners (GP) or haematologists. The aim of our study was to assess the quality of anticoagulation control with vitamin K antagonists (VKAs) in relation to the responsible specialist in a "real-world" AF population.

METHODS

We consecutively enrolled VKA anticoagulated patients included in the FANTASIIA Registry from 2013 to 2015. We analysed demographical, clinical characteristics and the quality of anticoagulation control according to the specialist responsible (ie GPs or haematologists).

RESULTS

Data on 1584 patients were included (42.5% females, mean age 74.0 ± 9.4 years): 977 (61.7%) patients were controlled by GPs and 607 (38.3%) by haematologists. Patients managed by GPs had higher previous heart disease (53.2% vs 43.3%, P < .001), heart failure (32.9% vs 26.5%, P < .008) and dilated cardiomyopathy (15.2% vs 8.7%, P < .001) with better renal function (69.3 ± 24.7 vs 63.1 ± 21.4 mL/min, P < .001) compared to patients managed by haematologists. There was no difference between groups in the type of AF, CHA₂ DS₂ -VASc or HAS-BLED scores, but patients with electrical cardioversion were more prevalent in GP group. The overall mean time in therapeutic range (TTR) assessed by Rosendaal method was 61.5 ± 24.9%; 52.6% of patients had TTR<65% and 60% of patients had TTR<70%. TTR was significantly lower in patients controlled by haematologists than by GPs (63 ± 24.4 vs 59.2 ± 25.6, P < .005).

CONCLUSIONS

About 60% of AF patients anticoagulated with VKAs had poor anticoagulation control (ie TTR<70%), and their management was only slightly better than when it is managed by general practitioners.

Impact of provision of time in therapeutic range value on anticoagulation management in atrial fibrillation patients on warfarin

INTRODUCTION

The importance of time in therapeutic range (TTR) in patients prescribed warfarin therapy for stroke prevention in atrial fibrillation (AF) cannot be overemphasised.

AIM

To evaluate the impact of provision of TTR results during clinic visits on anticoagulation management.

DESIGN

Single-centred, randomised controlled study.

SETTING

Fifteen arrhythmia clinics in Hong Kong.

PATIENTS

AF patients prescribed warfarin.

INTERVENTIONS

Provision of TTR or no provision of TTR.

MAIN OUTCOME MEASURES

A documented discussion between doctors and patients about switching warfarin to a non-vitamin K oral anticoagulant (NOAC).

RESULTS

Four hundred and eighty one patients with AF prescribed warfarin were randomly assigned to (1) a TTR provision group or (2) control. Their mean age was 73.6±12.0 years and 60.7% were men. The mean CHA₂DS₂-VASc score was 3.2±1.6 and the mean HASBLED score was 1.7±1.2. The mean TTR was 63.9%±29.9%. At the index clinic visit, 71 of 481 patients (14.8%) had a documented discussion about switching warfarin to a NOAC. Patients with provision of TTR results were more likely to discuss switching warfarin to a NOAC than controls (19.1% vs 10.6%, P=0.03), especially those with a TTR <65% (35.2% vs 10.6%, P<0.001). A higher proportion of patients with provision of TTR results switched to a NOAC (5.9% vs 4.1%, P=0.49).

CONCLUSIONS

The provision of TTR among patients on warfarin was associated with a discussion about switching from warfarin to a NOAC in those with TTR <65%, but did not result in actual switching to a NOAC, suggesting additional barriers.

Control of anticoagulation with vitamin K antagonists: overestimation of median time in therapeutic range when assessed by linear interpolation

Patients receiving vitamin K–antagonists are monitored by regular assessment of the International Normalized Ratio (INR). There are two popular methods for therapeutic control of anticoagulation in patient groups: 1) Time in Therapeutic Range (TTR) assessed by linear interpolation of successive INR measurements; 2) the cross-sectional proportion (CSP) of all patients’ last INRs within range. The purpose of the present study is to compare the two methods using data from 53 Dutch Thrombosis Centres and to develop a semi-quantitative model for TTR based on different types of INR change. Different groups of around 400,000 patients in four consecutive years were evaluated: patients in the induction phase, short-term, long-term, low-target range, high-target range, receiving either acenocoumarol or phenprocoumon, and performing self-management. Each Centre provided TTR and CSP results for each patient group. TTR and CSP were compared using the Wilcoxon signed-rank test. Separately, we analysed the relationship between consecutive INR results regarding in or out of range and their frequency of occurrence in patients of two different cohorts. Good correlation was observed between TTR and CSP (correlation coefficient 0.694–0.950 in low-target range). In long-term acenocoumarol patients (low-target range) the median TTR was significantly higher than CSP (80.0 % and 78.7 %, respectively; p<0.001). In long-term phenprocoumon patients (low-target range) there was no significant difference between median TTR (83.0 %) and median CSP (82.6 %). In conclusion, the correlation between TTR assessed by linear interpolation and CSP was good. TTR assessed by linear interpolation was higher than CSP in patients on acenocoumarol.

The importance of mean time in therapeutic range for complication rates in warfarin therapy of patients with atrial fibrillation: A systematic review and meta-regression analysis

Background

\Anticoagulation is used for stroke prophylaxis in non-valvular atrial fibrillation, amongst other by use of the vitamin K antagonist, warfarin. Quality in warfarin therapy is often summarized by the time patients spend within the therapeutic range (percent time in therapeutic range, TTR). The correlation between TTR and the occurrence of complications during warfarin therapy has been established, but the influence of patient characteristics in that respect remains undetermined. The objective of the present papers was to examine the association between mean TTR and complication rates with adjustment for differences in relevant patient cohort characteristics.

Methods

A systematic literature search was conducted in MEDLINE and Embase (2005–2015) to identify eligible studies reporting on use of warfarin therapy by patients with non-valvular atrial fibrillation and the occurrence of hemorrhage and thromboembolism. Both randomized controlled trials and observational cohort studies were included. The association between the reported mean TTR and major bleeding and stroke/systemic embolism was analyzed by random-effects meta-regression with and without adjustment for relevant clinical cohort characteristics. In the adjusted meta-regressions, the impact of mean TTR on the occurrence of hemorrhage was adjusted for the mean age and the proportion of populations with prior stroke or transient ischemic attack. In the adjusted analyses on thromboembolism, the proportion of females was, furthermore, included.

Results

Of 2169 papers, 35 papers met pre-specified inclusion criteria, holding relevant information on 31 patient cohorts. In univariable meta-regression, increasing mean TTR was significantly associated with a decreased rate of both major bleeding and stroke/systemic embolism. However, after adjustment mean TTR was no longer significantly associated with stroke/systemic embolism. The proportion of residual variance composed by between-study heterogeneity was substantial for all analyses.

Conclusions

Although higher mean TTR in warfarin therapy was associated with lower complication rates in atrial fibrillation, the strength of the association was decreased when adjusting for differences in relevant clinical characteristics of the patient cohorts. This study suggests that mainly the safety of warfarin therapy increases with higher mean TTR, whereas effectiveness appears not to be substantially improved.

Due to the limitations immanent in the meta-regression methods, the results of the present study should be interpreted with caution. Further research on the association between the quality of warfarin therapy and risk of complications is warranted with adjustment for clinically relevant characteristics.