Outpatient management of oral vitamin K antagonist therapy: defining and measuring high-quality management

Outcomes of Warfarin Home INR Monitoring vs Office-Based Monitoring: a Retrospective Claims-Based Analysis

BACKGROUND

Home INR testing (patient self-testing) is feasible and effective for warfarin patients but little is known about real-world differences in outcomes for patients using PST versus laboratory-based INR monitoring.

OBJECTIVE

To compare the safety/efficacy of patient self-testing of real-world warfarin therapy versus office/lab-based monitoring of therapy.

DESIGN/SETTING/PARTICIPANTS/EXPOSURE

A retrospective claims-based analysis of warfarin patients enrolled in the MarketScan® Commercial Claims and Encounters and Medicare databases between January 1, 2013, and March 30, 2020. Stratification was based on INR testing method: patient self-testing versus testing at physicians' offices/local laboratory. The probability of adverse events in each cohort was determined after adjusting for demographic and baseline clinical characteristics using a repeated measures analysis.

MAIN MEASURES

Rates of all adverse events: deep venous thrombosis, pulmonary embolism, bleeding, and stroke. A secondary outcome of interest was emergency department visits.

KEY RESULTS

A total of 37,837 patients were included in the analysis: 1592 patients in the patient self-testing group and 36,245 in the office-based therapy group. After adjusting for demographic and baseline clinical characteristics, patients in the office-based group had statistically significantly higher rates of all adverse events (incidence rate ratio [IRR]=2.07, 95% CI [1.82, 2.36]), and specific adverse events including thromboembolism (IRR=4.38, 95% CI [3.29, 5.84]), major bleed (IRR=1.45, 95% CI [1.28, 1.64]), and stroke (IRR=1.30, 95% CI [1.05, 1.61]) than patients in the patient self-testing group. Office-based patients also had a statistically significant higher rate of emergency department visits than patient self-testing patients (IRR = 1.65, 95% CI [1.47, 1.84]).

CONCLUSIONS/RELEVANCE

This analysis of real-world claims data shows lower rates of stroke, thromboembolism, and major bleeding, as well as fewer emergency department visits, with patient self-testing compared to office-based/lab INR monitoring. Our finding that PST is safe and effective among current users suggests that more patients may benefit from its use.

Utility of a pharmacist-managed Anticoagulation Program in patients with congenital heart disease

BACKGROUND

Warfarin remains the preferred anticoagulant for many patients with CHD. The complexity of management led our centre to shift from a nurse-physician-managed model with many providers to a pharmacist-managed model with a centralized anticoagulation team. We aim to describe the patient cohort managed by our Anticoagulation Program and evaluate the impact of implementation of this consistent, pharmacist-managed model on time in therapeutic range, an evidence-based marker for clinical outcomes.

METHODS

A single-centre retrospective cohort study was conducted to evaluate the impact of the transition to a pharmacist-managed model to improve anticoagulation management at a tertiary pediatric heart centre. The percent time in therapeutic range for a cohort managed by both models was compared using a paired t-test. Patient characteristics and time in therapeutic range of the program were also described.

RESULTS

After implementing the pharmacist-managed model, the time in therapeutic range for a cohort of 58 patients increased from 65.7 to 80.2% (p < .001), and our Anticoagulation Program consistently maintained this improvement from 2013 to 2022. The cohort of patients managed by the Anticoagulation Program in 2022 included 119 patients with a median age of 24 years (range 19 months-69 years) with the most common indication for warfarin being mechanical valve replacement (n = 81, 68%).

CONCLUSIONS

Through a practice change incorporating a collaborative, centralized, pharmacist-managed model, this cohort of CHD patients on warfarin had a fifteen percent increase in time in therapeutic range, which was sustained for nine years.

Online KidClot education for patients and families initiating warfarin therapy: The eKITE study

Anticoagulation with Vitamin K antagonists (VKA) has always posed challenges in terms of monitoring requirements. These challenges were further exacerbated in the setting of the COVID-19 pandemic, with limited access to and/or avoidance of laboratory testing. The importance of utilizing point of care (POC) health technology for individualized patient management is salient. The foundation of effective home INR monitoring is establishing patient knowledge about their therapy and INR testing proficiency. The eKITE series was developed to support patients in establishing foundational knowledge required for VKA (warfarin) management and INR monitoring. The primary objectives were to evaluate eKITE, a patient-oriented innovative online education program for warfarin therapy, participant learning stress, and patient preference for online learning. This multi-center prospective study provided patients access to warfarin online education. Participants were required to complete written quizzes assessing warfarin knowledge of key concepts proficiency and identifying knowledge deficits. Patient preference, evaluating calm (lack of anxiety) while learning, and an INR on a home meter was completed. Participants performed INR tests at home and reported INRs by telephone. The analysis included 144 children and caregivers enrolled at five US and CDN sites. Most indications for anticoagulation were cardiac (congenital or acquired heart disease) with varied INR target ranges. Mean knowledge scores for warfarin and INR self-testing modules were 97%, with low anxiety with TTR of 84%. Patient preferred online learning. eKITE is an effective teaching modality for warfarin/home INR monitoring with safe INR testing and warfarin management that is appropriate for pediatrics and adults alike. PROLOGUE: The whir in the hallways is deafening. Lights bright, alarms are ringing in a chorus of unsynchronized beeps and screeches. It has been more than a week since I have slept. Snuggled beside me is my precious child, whining and equally irritated with the asynchronous symphony, further compounded by anxiety, procedures, and pain. The sun has broken. The staff smiles are welcoming and incessant, as one after one, they approach hurried, urgent, assiduous, their need to coach me for our upcoming departure to the warmth of home. Each provides essential information that I will require to keep my child, my treasure, safe and healthy. Yet, my eyes are heavy, blurred, and my brain foggy, trapped in a dark heavy cloud. How am I to follow? Comprehend? and retain anything? As they instruct, my precious child yearns for loving arms, compassion and love, whining, crying in disquiet. Overwhelmed does not adequately describe my ineffable exhaustion. Amidst this, how am I to learn about warfarin? Such a challenging medication, with so much to know. Concentrate, I tell myself, focus; now is my only opportunity to learn. I must be alert. It seems to be nonsensical.

Clinical Outcomes of Different Warfarin Self-Care Strategies: A Systematic Review and Network Meta-Analysis

AIM

To compare the effects of different strategies for warfarin self-care.

METHODS

PubMed, EMBASE, CENTRAL, CINAHL, ProQuest Dissertations & Theses, and OpenGrey were searched from inception to August 2021. Randomized controlled trials (RCTs) of warfarin self-care, either patient self-testing (PST) or patient self-management (PSM), were included. Self-care approaches were classified based on the TIP framework (theme, intensity, provider): (1) PST ≥1/week via e-Health (PST/High/e-Health); (2) PST ≥1/week by health care practitioner (PST/High/HCP); (3) PST <1/week via e-Health (PST/Low/e-Health); (4) PSM ≥1/week by e-Health (PSM/High/e-Health); (5) PSM ≥1/week by patient (PSM/High/Pt); (6) PSM <1/week by patient (PSM/Low/Pt); and (7) PSM with flexible frequency by patient (PSM/Flex/Pt). Mean differences (MDs) and risk ratios (RRs) with 95% confidence interval (CI) were estimated using frequentist network meta-analyses with a random-effects model. The certainty of evidence was evaluated using CINeMA (Confidence in Network Meta-Analysis).

RESULTS

Sixteen RCTs involving 5,895 participants were included. When compared with usual care, time in therapeutic range was higher in PSM/High/Pt and PST/High/e-Health with MD [95% CI] of 7.67% [0.26-15.08] and 5.65% [0.04-11.26], respectively. The certainty of evidence was rated as moderate for these findings. The risk of thromboembolic events was lower in the PSM/Flex/Pt group when compared with PST/High/e-Health (RR: 0.39 [0.20-0.77]) and usual care (RR: 0.38 [0.17-0.88]) with low and very low level of evidence, respectively. There was no significant difference in the proportion of international normalized ratio (INR) values in range, major bleeding, and all-cause mortality among different self-care features.

CONCLUSION

Patient self-care (either PST or PSM) by measuring INR values at least once weekly is more effective in controlling the INR level.

Impact of CYP3A5 phenotype on tacrolimus time in therapeutic range and clinical outcomes in pediatric renal and heart transplant recipients

STUDY OBJECTIVE

This study investigated the effect of CYP3A5 phenotype on time in therapeutic range (TTR) of tacrolimus post-transplant in pediatric patients.

DESIGN AND DATA SOURCE

This retrospective study assessed medical records of pediatric kidney and heart recipients with available CYP3A5 genotype for tacrolimus dosing, troughs, and the clinical events (biopsy-proven acute rejection [BPAR] and de novo donor-specific antibodies [dnDSA]).

MEASUREMENTS AND MAIN RESULTS

The primary outcome, mean TTR in the first 90 days post-transplant, was 9.0% (95% CI: -16.1, -1.9) lower in CYP3A5 expressers (p = 0.014) when adjusting for time to therapeutic concentration and organ type. There was no difference between CYP3A5 phenotypes in time to the first clinical event using TTR during the first 90 days. When applying TTR over the first year, there was a significant difference in event-free survival (EFS) which was 50.0% for CYP3A5 expressers/TTR < 35%, 45.5% for expressers/TTR ≥ 35%, 38.1% for nonexpressers/TTR < 35%, and 72.9% for nonexpressers/TTR ≥ 35% (log-rank p = 0.03). A post hoc analysis of EFS identified CYP3A5 expressers had lower EFS compared to nonexpressers in patients with TTR ≥ 35% (p = 0.04) but no difference among patients with TTR < 35% (p = 0.6).

CONCLUSIONS

The relationship between TTR and CYP3A5 phenotype suggests that achieving a TTR ≥ 35% during the first year may be a modifiable factor to attenuate the risk of BPAR and dnDSA.

Association between Patients' Knowledge and Adherence to Anticoagulants, and Its Effect on Coagulation Control

BACKGROUND

Warfarin requires strict monitoring by measuring prothrombin time (PT), international normalized ratio (INR), and time in therapeutic range (TTR). Several factors can lead to poor PT/INR control including vitamin K status, medication adherence, knowledge, and quality of life. The present study aims to assess patient adherence to warfarin treatment and its correlation with INR control.

METHODS

A cross-sectional study was conducted between October 2017 and January 2018 at Tripoli University Hospital. Data were collected by structured questionnaires which included; demographic and clinical characteristics, the Oral Anticoagulation Knowledge (OAK) test, and the Morisky Medication Adherence Scale (MMAS-8).

RESULTS

The final analysis included 88 out of 140 patients (73.33%). There were significant differences in age range, gender, marital status, and education level between the 2 groups (poor knowledge and adequate knowledge) (p < 0.05). There was a significant positive correlation between OAK test score and TTR. Overall, 76.2% of patients were adherent to warfarin (MMAS score ≥6) and 20.45% of patients were of high adherence (MMAS score of 8). The median score was 6 (IQR 6-7). A statistically significant, strong positive correlation between adherence to medication and TTR as an indicator of INR control was found (rs[86] = 0.472, p < 0.0001).

CONCLUSION

The study addressed and identified several areas for future improvement of patient outcomes. The implementation of new approaches to enhance patient knowledge and adherence is warranted, and measures to provide treatment for all patients that require it are needed, to improve outcomes and decrease adverse drug effects.

Health Economic Analysis of Rivaroxaban and Warfarin for Venous Thromboembolism Management in Chinese Patients

PURPOSE

Rivaroxaban, a direct oral anticoagulant, has demonstrated non-inferiority to warfarin for venous thromboembolism (VTE) treatment in clinical trials. This study aimed to analyze the direct medical costs for VTE management with rivaroxaban versus warfarin in Hong Kong Chinese patients.

METHODS

In this retrospective observational study, VTE patients admitted to the Princess Margaret Hospital from March 2012 to February 2017 who were initiated and discharged with either rivaroxaban or warfarin were included. Patient demographic and clinical data, and healthcare resource utilization for VTE management were collected for the VTE index admission and 1-year post-discharge period.

RESULTS

A total of 181 patients (90 in the rivaroxaban group; 91 in the warfarin group) were included. The mean (± SD) length of stay (LOS) was 4.8 ± 2.7 days and 8.0 ± 3.0 days in the rivaroxaban and warfarin groups, respectively (p > 0.001). The total cost for VTE index admission in the rivaroxaban group was significantly lower than that of the warfarin group (USD 5473 ± 1914 versus USD 3457 ± 1796; p < 0.001) (USD 1 = HKD 7.8). Recurrent VTE and bleeding rates in 1-year post-discharge period were not significantly different between the two groups. The direct total cost of the rivaroxaban group (USD 1271 ± 767) was significantly lower than that of the warfarin group (USD 1739 ± 1045) in 1-year post-discharge period (p < 0.001).

CONCLUSIONS

Total direct cost and LOS for VTE admission and total cost in 1-year post-discharge period were significantly lower in patients initiated and discharged with rivaroxaban than those of warfarin.

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.

Experiencia de validación de material educativo pacientes anticoagulados en un servicio de consulta externa

La terapia con anticoagulantes está indicada en los procesos trombóticos y requieren un manejo integral para reducir los eventos adversos. Las medidas para el seguimiento incluyen monitorización,  vigilancia y educación continua creando alternativas pedagógicas que facilitan los procesos de recepción y apropiación de la información. Objetivo: validar el material educativo para el paciente anticoagulado asistente al servicio de hematología. Metodología: la experiencia se desarrolló en tres fases: búsqueda bibliográfica, construcción y diseño del material educativo, y validación. Para esta fase se realizaron dos procesos, uno de validación técnica y otro con la comunidad. Resultados: se identificaron 19 documentos, ninguno reportó procesos de validación. Con base en la documentación analizada se consideró que el material más adecuado para la población era una cartilla educativa. Discusión: los materiales educativos para pacientes son una herramienta utilizada  con frecuencia por el sistema de salud, como complemento de la atención que se realiza por fuera de la consulta médica, pero son escasos los procesos de validación rigurosa de este tipo de material en el área de hematología.

A rapid evidence assessment of bleed-related healthcare resource utilization in publications reporting the use of direct oral anticoagulants for non-valvular atrial fibrillation

Objective: Non-valvular atrial fibrillation (NVAF), a common cardiac arrhythmia, is associated with high morbidity and carries a substantial economic burden. Historically, vitamin K antagonists (VKAs; e.g. warfarin) have been used for therapy of NVAF, but recently several direct oral anticoagulants (DOACs) have been approved for prevention of stroke in patients with NVAF. This review summarizes the real-world evidence (RWE) for healthcare resource utilization (HRU) in patients receiving oral anticoagulants (VKAs and/or DOACs) for therapy of NVAF.Methods: A PRISMA-compliant literature search assessed Medline^® and Embase^® databases from 1 January 2011 to 4 May 2017, and the National Health Service Economic Evaluation Database from 1 January 2011 to 31 December 2015. Publications were included if they reported observational data from real-world use of one or more anticoagulant therapies. Outcomes of interest included hospitalizations, length of stay (LOS), mortality and costs.Results: Twenty-eight publications were included. Apixaban and dabigatran were associated with fewer bleed-related hospitalizations than warfarin. Bleed-related LOS were generally longer for warfarin than for DOACs. Bleed-related treatment costs were lower for patients receiving apixaban or receiving dabigatran than patients receiving rivaroxaban or receiving warfarin. Bleed-related mortality in patients receiving oral anticoagulation for treatment of NVAF were low across all DOACs and warfarin.Conclusions: The limited available evidence for HRU burden among patients receiving oral anticoagulation for NVAF suggests that DOACs (particularly apixaban and dabigatran) offer some degree of benefit in terms of HRU outcomes, compared with warfarin. Further work is required to understand HRU outcomes in patients receiving DOACs.

Follow-up and management of valvular heart disease patients with prosthetic valve: a clinical practice guideline for Indian scenario

PURPOSE

Valvular heart disease (VHD) patients after prosthetic valve implantation are at risk of thromboembolic events. Follow-up care of patients with prosthetic valve has a paramount role in reducing the morbidity and mortality. Currently, in India, there is quintessential need to stream line the follow-up care of prosthetic valve patients. This mandates the development of a consensus guideline for the antithrombotic therapy in VHD patients post prosthetic valve implantation.

METHODS

A national level panel was constituted comprising 13 leading cardio care experts in India who thoroughly reviewed the up to date literature, formulated the recommendations, and developed the consensus document. Later on, extensive discussions were held on this draft and the recommendations in 8 regional meetings involving 79 additional experts from the cardio care in India, to arrive at a consensus. The final consensus document is developed relying on the available evidence and/or majority consensus from all the meetings.

RESULTS

The panel recommended vitamin K antagonist (VKA) therapy with individualized target international normalized ratio (INR) in VHD patients after prosthetic valve implantation. The panel opined that management of prosthetic valve complications should be personalized on the basis of type of complications. In addition, the panel recommends to distinguish individuals with various co-morbidities and attend them appropriately.

CONCLUSIONS

Anticoagulant therapy with VKA seems to be an effective option post prosthetic valve implantation in VHD patients. However, the role for non-VKA oral therapy in prosthetic valve patients and the safety and efficacy of novel oral anticoagulants in patients with bioprosthetic valve need to be studied extensively.

Optimizing quality care for the oral vitamin K antagonists (VKAs)

Vitamin K antagonists (VKAs) have been the only oral anticoagulants for decades. The management of anticoagulant therapy with VKA is challenging because of the intricate pharmacological properties of these agents. The success of VKA therapy depends on the quality of treatment that is ensured through continuing comprehensive communication and education. The educational program should address important issues of the VKA therapy such as beginning of treatment, pharmacological, dietary, and drug-drug interactions, as well as treatment temporary suspension during surgical interventions or invasive maneuvers. In addition, the initial and continuing patient education is of imperative importance. A major role in the educational process may be addressed by patient associations. The quality of treatment is better reached if patients are followed in anticoagulation clinics. Moreover, a federation of anticoagulation clinics may improve patient care through regular meetings to update knowledge on VKA treatment. Learning objectives of this paper is to allow readers to correctly approach patients starting VKA treatment, recognize possible pitfalls of treatment, and provide adequate solutions.

Retrospective cohort study for evaluating the INR monitoring patterns in patients with deep vein thrombosis in daily practice: Analysis of 2010-2013 database of a tertiary care center

OBJECTIVE

To evaluate the international normalized ratio (INR) monitoring patterns in patients with deep vein thrombosis.

METHODS

Of 32,012 patients with ≥1 outpatient INR measurement and 42,582 patients with confirmed deep vein thrombosis diagnosis registered to our hospital between 1 January 2010 and 31 December 2013, 6720 records were identified to have both deep vein thrombosis and international normalized ratio measurement, and 4.377 out of 6.720 single patient records were determined to be statistically analyzable.

RESULTS

Median INR measurement frequency was 6.47 times/year and patients had INR levels of 2-3 in 34.3% of follow-up time. Having ≥70% vs. <70% of follow-up time within therapeutic range was associated with lower hospital admission frequency (9.7 vs. 10.3 times/year).

CONCLUSION

Our study revealed only one-third of the follow-up time to be spent within therapeutic INR, association of INR therapeutic range with lesser number of hospital admissions and INR monitoring frequency of 6.47 times/year despite lack of stable INR control in most of the deep vein thrombosis patients.

Therapeutic endoscopy-related GI bleeding and thromboembolic events in patients using warfarin or direct oral anticoagulants: results from a large nationwide database analysis

OBJECTIVE

To compare the risks of postendoscopy outcomes associated with warfarin with direct oral anticoagulants (DOACs), taking into account heparin bridging and various types of endoscopic procedures.

DESIGN

Using the Japanese Diagnosis Procedure Combination database, we identified 16 977 patients who underwent 13 types of high-risk endoscopic procedures and took preoperative warfarin or DOACs from 2014 to 2015. One-to-one propensity score matching was performed to compare postendoscopy GI bleeding and thromboembolism between the warfarin and DOAC groups.

RESULTS

In the propensity score-matched analysis involving 5046 pairs, the warfarin group had a significantly higher proportion of GI bleeding than the DOAC group (12.0% vs 9.9%; p=0.002). No significant difference was observed in thromboembolism (5.4% vs 4.7%) or in-hospital mortality (5.4% vs 4.7%). The risks of GI bleeding and thromboembolism were greater in patients treated with warfarin plus heparin bridging or DOACs plus bridging than in patients treated with DOACs alone. Compared with percutaneous endoscopic gastrostomy, patients who underwent endoscopic submucosal dissection, endoscopic mucosal resection and haemostatic procedures including endoscopic variceal ligation or endoscopic injection sclerotherapy were at the highest risk of GI bleeding among the 13 types of endoscopic procedures, whereas those who underwent lower polypectomy endoscopic sphincterotomy or endoscopic ultrasound-guided fine needle aspiration were at moderate risk.

CONCLUSION

The risk of postendoscopy GI bleeding was higher in warfarin than DOAC users. Heparin bridging was associated with an increased risk of bleeding and did not prevent thromboembolism. The bleeding risk varied by the type of endoscopic procedure.

Heart Failure Severity and Quality of Warfarin Anticoagulation Control (From the WARCEF Trial)

Previous studies in patients with atrial fibrillation showed that a history of heart failure (HF) could negatively impact anticoagulation quality, as measured by the average time in therapeutic range (TTR). Whether additional markers of HF severity are associated with TTR has not been investigated thoroughly. We aimed to examine the potential role of HF severity in the quality of warfarin control in patients with HF with reduced ejection fraction. Data from the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction Trial were used to investigate the association between TTR and HF severity. Multivariable logistic regression models were used to examine the association of markers of HF severity, including New York Heart Association (NYHA) class, Minnesota Living with HF (MLWHF) score, and frequency of HF hospitalization, with TTR ≥70% (high TTR). We included 1,067 participants (high TTR, N = 413; low TTR, N = 654) in the analysis. In unadjusted analysis, patients with a high TTR were older and less likely to have had strokes or receive other antiplatelet agents. Those patients also had lower NYHA class, better MLWHF scores, greater 6-minute walk distance, and lower frequency of HF hospitalizations. Multivariable analysis showed that NYHA class III and/or IV (Odds ratio [OR] 0.68 [95% confidence intervals [CIs] 0.49 to 0.94]), each 10-point increase in MLWHF score (i.e., worse health-related quality of life) (OR 0.92 [0.86 to 0.99]), and higher number of HF hospitalization per year (OR0.45 [0.30 to 0.67]) were associated with decreased likelihood of having high TTR. In HF patients with systolic dysfunction, NYHA class III and/or IV, poor health-related quality of life, and a higher rate of HF hospitalization were independently associated with suboptimal quality of warfarin anticoagulation control. These results affirm the need to assess the new approaches, such as direct oral anticoagulants, to prevent thromboembolism in this patient population.

Clinical Outcomes of Telemonitoring for Patients on Warfarin after Discharge from Hospital

OBJECTIVE

To evaluate the impact of telephone follow-up service on clinical outcomes in patients on warfarin when discharged from hospital.

METHODS

This randomized controlled trial was conducted at a general hospital in Thailand. Patients aged ≥20 years who were prescribed warfarin when discharged were eligible to participate in this study. They were randomly allocated, using a computer generated random number, to receive either telephone follow-up intervention or usual care. Participants in the intervention group received telephone follow-up by hospital pharmacists for three months. During each telephone call, pharmacists performed medicine use reviews and addressed any problems identified.

KEY FINDINGS

A total of 50 patients participated in this study. The proportion of international normalized ratio (INR) values in the target range for the telephone follow-up group (36/79, 45.6%) was higher than that in the usual care group (19/79, 24.1%), p=0.005. The mean time in the therapeutic range (TTR) in the telephone follow-up group was also higher than that in the usual care group (49.8±34.3 versus 28.0±27.5, p=0.017). All patients in the usual care group experienced one or more out-of-range INR values (25/25, 100%) compared to 21 out of 25 (84%) in the telephone follow-up group, p=0.037. There was no difference between the two groups in the incidence of complications or adverse events associated with warfarin.

CONCLUSIONS

The telephone follow-up service in recently discharged patients helps them achieve and maintain their INR target. This anticoagulant supportive service should be promoted to patients receiving warfarin therapy after discharge. This trial is registered with TCTR20180614006 (Thai Clinical Trials Registry).

Post-polypectomy bleeding and thromboembolism risks associated with warfarin vs direct oral anticoagulants

AIM

To verify the validity of the endoscopy guidelines for patients taking warfarin or direct oral anticoagulants (DOAC).

METHODS

We collected data from 218 patients receiving oral anticoagulants (73 DOAC users, 145 warfarin users) and 218 patients not receiving any antithrombotics (age- and sex-matched controls) who underwent polypectomy. (1) We evaluated post-polypectomy bleeding (PPB) risk in patients receiving warfarin or DOAC compared with controls; (2) we assessed the risks of PPB and thromboembolism between three AC management methods: Discontinuing AC with heparin bridge (HPB) (endoscopy guideline recommendation), continuing AC, and discontinuing AC without HPB.

RESULTS

PPB rate was significantly higher in warfarin users and DOAC users compared with controls (13.7% and 13.7% vs 0.9%, P < 0.001), but was not significantly different between rivaroxaban (13.2%), dabigatran (11.1%), and apixaban (13.3%) users. Two thromboembolic events occurred in warfarin users, but none in DOAC users. Compared with the continuing anticoagulant group, the discontinuing anticoagulant with HPB group (guideline recommendation) had a higher PPB rate (10.8% vs 19.6%, P = 0.087). These findings were significantly evident in warfarin but not DOAC users. One thrombotic event occurred in the discontinuing anticoagulant with HPB group and the discontinuing anticoagulant without HPB group; none occurred in the continuing anticoagulant group.

CONCLUSION

PPB risk was similar between patients taking warfarin and DOAC. Thromboembolism was observed in warfarin users only. The guideline recommendations for HPB should be re-considered.

Lower tacrolimus exposure and time in therapeutic range increase the risk of de novo donor-specific antibodies in the first year of kidney transplantation

De novo donor-specific antibodies (dnDSAs) have been associated with reduced graft survival. Tacrolimus (TAC)-based regimens are the most common among immunosuppressive approaches used in in clinical practice today, yet an optimal therapeutic dose to prevent dnDSAs has not been established. We evaluated mean TAC C0 (tacrolimus trough concentration) and TAC time in therapeutic range for the risk of dnDSAs in a cohort of 538 patients in the first year after kidney transplantation. A mean TAC C0  < 8 ng/mL was associated with dnDSAs by 6 months (odds ratio [OR] 2.51, 95% confidence interval [CI] 1.32-4.79, P = .005) and by 12 months (OR 2.32, 95% CI 1.30-4.15, P = .004), and there was a graded increase in risk with lower mean TAC C0 . TAC time in the therapeutic range of <60% was associated with dnDSAs (OR 2.05, 95% CI 1.28-3.30, P = .003) and acute rejection (hazard ratio [HR] 4.18, 95% CI 2.31-7.58, P < .001) by 12 months and death-censored graft loss by 5 years (HR 3.12, 95% CI 1.53-6.37, P = .002). TAC minimization may come at a cost of higher rates of dnDSAs, and TAC time in therapeutic range may be a valuable strategy to stratify patients at increased risk of adverse outcomes.

Use of neutrophil-lymphocyte ratio for risk stratification and relationship with time in therapeutic range in patients with nonvalvular atrial fibrillation: A pilot study

BACKGROUND

Atrial fibrillation is one of the most common abnormal heart rhythms. Neutrophil-lymphocyte ratio (NLR) has emerged as a potential marker for the level of inflammation in cardiac disorders.

HYPOTHESIS

NLR might be associated with thrombosis and bleeding risk scores and might predict cardioembolic risk in nonvalvular atrial fibrillation (NVAF) patients within the therapeutic international normalized ratio (INR).

METHODS

We enrolled 272 patients taking warfarin for NVAF and classified them into 2 groups: Group A consisted of patients (n = 132) whose time in therapeutic range (TTR) was ≥65%, and Group B comprised patients (n = 139) whose TTR was <65%.

RESULTS

NLR values were higher in group B than in group A (P < 0.0001). Patients classified as high risk according to CHA₂ DS₂ -VASc score had significantly higher NLR levels (P = 0.002) than those classified as low and intermediate risk. Furthermore, NLR levels were significantly correlated with CHA₂ DS₂ -VASc and HAS-BLED scores (P < 0.001 and P < 0.0001, respectively). NLR predicted patients within therapeutic INR range (TTR ≥65%) with sensitivity of 81% and specificity of 71% in a receiver operator characteristic curve analysis, using a cutoff value of 2.17. Area under the curve for NLR was 0.81 (P < 0.0001).

CONCLUSIONS

To our knowledge, this is the first study showing correlation of NLR with both CHA₂ DS₂ -VASc and HAS-BLED risk scores. NLR might represent a useful marker to identify patients with high risks of stroke and bleeding and may have predictive value in identifying patients within the therapeutic INR range.

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.

Quality of anticoagulation management with warfarin among outpatients in a tertiary hospital in Addis Ababa, Ethiopia: a retrospective cross-sectional study

Background

Warfarin is the most widely used anticoagulant in the world. The difficulty of managing warfarin contributes to great potential for patient harm, both from excessive anticoagulation and insufficient anticoagulation. This study assessed the International Normalized Ratio (INR) control outcome measures and warfarin dose adjustment practices at cardiology and hematology outpatient clinics at a teaching hospital in Addis Ababa, Ethiopia.

Methods

The study was based on a cross - sectional study design involving 360 retrospective patients’ chart review among outpatients who received warfarin for its various indications.

Results

The mean frequency of INR monitoring per patient was 62.9 days (17.2–143.7 days).

Patients spent 52.2%, 29.0% and 18.8% of the time in sub-therapeutic, therapeutic and supra-therapeutic ranges, respectively. The daily warfarin dose was increased 50.9% and 36.9% and decreased in 52.8% and 60.9% of the time for occurrences of sub-therapeutic and supra-therapeutic INRs to achieve target ranges of 2.0–3.0 and 2.5–3.5, respectively.

Conclusion

The quality of anticoagulation management with warfarin among outpatients in Tikur Anbessa Specialized Hospital was sub-optimal. This was reflected by low Time in Therapeutic Range (TTR), longer than recommended INR monitoring frequency, and minimal actions taken to adjust warfarin dose after occurrences of non-therapeutic INRs.

Comparison of the INR Values Measured by CoaguChek XS Coagulometer and Conventional Laboratory Methods in Patients on VKA Therapy

BACKGROUND

Warfarin, which is a widely used oral anticoagulant, has a narrow therapeutic window and requires regular international normalized ratio (INR) monitoring to maintain optimal anticoagulation. Recently, several portable coagulometers have been developed to measure INR levels.

OBJECTIVE

To compare the INR results obtained by a portable coagulometer (CoaguChek XS) and a standard laboratory method (STAGO STA-R).

METHODS

Overall, 433 consecutive patients (male: 191, median age: 61 [44-86] years) who were admitted to outpatient anticoagulation clinic were enrolled in this study. Each patient was tested for INR using portable CoaguChek XS and STAGO STA-R automatic laboratory coagulometer. Correlation between methods was assessed using the Pearson correlation test and Cohen κ test. Bland-Altman plot was used to identify mean difference and 95% limits of agreement.

RESULTS

The mean INR values for CoaguChek XS and STAGO STA-R were 2.54 ± 1.17 and 2.79 ± 1.39, respectively. There was a strong positive correlation between the 2 methods ( r = .966; 95% confidence interval [CI]: 0.95-0.97, P < .001). The Bland-Altman analysis gave a mean difference of 0.26 ± 0.40 between the 2 methods, with a 95% limit of agreement of -0.54 to 1.05. In patients with INR values >5.0, there was only a moderate correlation ( r = .676; 95% CI: 0.38-0.89, P = .002), and the mean difference of INR tended to increase as mean INR values increased. There was a high overall agreement between the 2 methods (κ = .751; 95% CI: 0.69-0.80; P < .001).

CONCLUSION

There was good consistency between traditional laboratory testing and CoaguChek XS coagulometer, which provides rapid and reliable INR analysis.

Challenges in achieving a target international normalized ratio for deep vein thrombosis among HIV-infected patients with tuberculosis: a case series

Background

Tuberculosis (TB) and HIV are among the risk factors for deep vein thrombosis (DVT). There are several challenges in the management of DVT patients with TB-HIV co-infection including drug-drug interactions and non-adherence due to pill burden.

Methods

HIV infected patients starting treatment for TB were identified and followed up two weekly. Cases of DVT were diagnosed with Doppler ultrasound and patients were initiated on oral anticoagulation with warfarin and followed up with repeated INR measurements and warfarin dose adjustment.

Results

We describe 7 cases of TB and HIV-infected patients in Uganda diagnosed with DVT and started on anticoagulation therapy. Their median age was 30 (IQR: 27–39) years and 86 % were male. All patients had co-medication with cotrimoxazole, tenofovir, lamivudine and efavirenz and some were on fluconazole. The therapeutic range of the International Normalization Ratio (INR) was difficult to attain and unpredictable with some patients being under-anticoagulated and others over-anticoagulated. The mean Time in Therapeutic Range (TTR) for patients who had all scheduled INR measurements in the first 12 weeks was 33.3 %. Only one patient among those with all the scheduled INR measurements had achieved a therapeutic INR by 2 weeks. Four out of seven (57 %) of the patients had at least one INR above the therapeutic range which required treatment interruption. None of the patients had major bleeding.

Conclusion

We recommend more frequent monitoring and timely dose adjustment of the INR, as well as studies on alternative strategies for the treatment of DVT in TB-HIV co-infected patients.

[Evaluation of the knowledge of patients about the management of treatment with anti-vitamin K drugs in the Service of Cardiology of Ouagadougou]

INTRODUCTION

Vitamin K antagonists (VKA), the most widely prescribed oral anticoagulant therapy, represent a major public health problem by the adverse events related to their use. The aim of this study was to clarify the level of knowledge that patients have about the management of their oral anticoagulant treatment.

PATIENTS AND METHODS

This was a descriptive cross-sectional study performed at Yalgado Ouedraogo university Hospital, over a period of three months starting from March 1st to May 31st 2012. A questionnaire was given to patients receiving VKA treatment for at least a month.

RESULTS

Seventy patients were enrolled in the study of which 30 men. The median age was 49±16 years. Heart disease and venous thromboembolic disease justifying the introduction of VKA treatment were found respectively in 58.6 and 41.4% of the cases. The name of the VKA and the exact reason for the treatment were known respectively in 91.4 and 61.7% of the case. More than half of patients (68.6%) knew that the VKA makes blood more fluid. Forty-six patients (65.7%) cited INR as biological monitoring of treatment but only 28 patients (40%) were aware of INR target values. The majority of patients did not know the risks in case of overdose (72.8%) and underdosing (71.4%). Self-medication by non-steroidal anti-inflammatory drugs was reported by 18 patients (25.7%). Cabbage (74.3%) and lettuce (62.9%) were the main foods reported to be consumed moderately.

CONCLUSION

The knowledge of patients on the management of VKA is fragmentary and remains insufficient to ensure the effectiveness of the treatment. The creation of a therapeutic education program is then necessary.

A before and after study of warfarin monitoring in a single region as part of the Scottish patient safety programme in primary care

Introduction

Warfarin is an effective drug for patients at risk of thromboembolic events, but sub-optimal pharmacological management may cause significant harm. As part of the Scottish patient safety programme in primary care, one health board region aimed to determine if the international normalised ratio control for patients taking warfarin in general practice improved over the first 12 months of participation.

Methods

A before and after study of a multi-intervention improvement strategy was employed that combined financial incentivisation, a regional learning collaborative, clinical care bundle implementation, audit and feedback and clinical ‘safety champions’. The main patient outcome measures were: mean time in therapeutic range; proportion with good control (time in therapeutic range >60%) and excellent control (time in therapeutic range > 75%); and the proportion of very abnormal results (international normalised ratio < 1.5 or >5). Chi-square tests were used to determine statistical differences.

Results

In total, 49 of 55 general practices participated (89%) with 33/55 providing usable data (60%) on 1480 patients (before) and 1946 patients (after), respectively. Improvements were observed in mean time in therapeutic range ( P < 0.05) as well as in the proportion of patients with good control (time in therapeutic range > 60%, P < 0.01) and excellent control (time in therapeutic range > 75%, P = 0.06). A reduction in the proportion of very abnormal results (international normalised ratio < 1.5 or >5) was also observed ( P < 0.01), while the mean number of patient attendances reduced ( P < 0.05).

Conclusions

The introduction of a complex safety improvement intervention via a national patient safety programme has resulted in modest improvements in the control of warfarin monitoring in a single region. These improvements may potentially reduce the incidence of serious adverse events. The study method, interventions and findings should be of interest to primary care settings with similar warfarin management arrangements internationally.

Comorbidities against quality control of VKA therapy in non-valvular atrial fibrillation: a French national cross-sectional study

Background

Given the prevalence of non-valvular atrial fibrillation in the geriatric population, thromboembolic prevention by means of vitamin K antagonists (VKA) is one of the most frequent daily concerns of practitioners. The effectiveness and safety of treatment with VKA correlates directly with maximizing the time in therapeutic range, with an International Normalized Ratio (INR) of 2.0-3.0. The older population concentrates many of factors known to influence INR rate, particularly concomitant medications and concurrent medical conditions, also defined as comorbidities.

Objective

Determine whether a high burden on comorbidities, defined by a Charlson Comorbidity Index (CCI) of 3 or greater, is associated a lower quality of INR control.

Study-Design

Cross-sectional study.

Settings

French geriatric care units nationwide.

Participants

2164 patients aged 80 and over and treated with vitamin K antagonists.

Measurements

Comorbidities were assessed using the Charlson Comorbidity Index (CCI). The recorded data included age, sex, falls, kidney failure, hemorrhagic event, VKA treatment duration, and the number and type of concomitant medications. Quality of INR control, defined as time in therapeutic range (TTR), was assessed using the Rosendaal method.

Results

487 patients were identified the low-quality control of INR group. On multivariate logistic regression analysis, low-quality control of INR was independently associated with a CCI ≥3 (OR = 1.487; 95% CI [1.15; 1.91]). The other variables associated with low-quality control of INR were: hemorrhagic event (OR = 3.151; 95% CI [1.64; 6.07]), hospitalization (OR = 1.614, 95% CI [1.21; 2.14]).

Conclusion

An elevated CCI score (≥3) was associated with low-quality control of INR in elderly patients treated with VKA. Further research is needed to corroborate this finding.

[Evaluation of the level of knowledge of patients on treatment with vitamin K antagonists in Ouagadougou cardiology department]

Introduction

Les antivitamines K (AVK), traitement anticoagulant oral le plus largement prescrit, posent un réel problème de santé publique du fait de leur risque iatrogène. L'objectif de cette étude était de préciser le niveau de connaissance des patients sur la gestion de leur traitement par les AVK.

Méthodes

Il s'est agi d'une enquête transversale descriptive réalisée au CHU-Yalgado Ouédraogo, sur une période de 03 mois : du 1er mars au 31 mai 2012. Un questionnaire a été administré aux patients bénéficiant d'un traitement AVK depuis au moins un mois.

Résultats

Soixante-dix patients ont été inclus dans l'étude dont 30 hommes. L'âge moyen était de 49 ans ± 16 ans. Les cardiopathies et la maladie thromboembolique veineuse justifiant l'institution du traitement AVK étaient retrouvées respectivement dans 58,6% et 41,4% des cas. Le nom de l'AVK et la raison exacte du traitement étaient connus respectivement dans 91,4% et 67,1% des cas. Plus de la moitié des patients (68,6%) savaient que les AVK rendaient le sang plus fluide. Quarante-six patients (65,7%) citaient l'INR comme examen biologique de surveillance du traitement et seulement 28 patients (40%) connaissaient les valeurs cibles. La majorité des patients ne connaissait pas les risques encourus en cas de surdosage (72,8%) et de sous-dosage (71,4%). Une automédication par anti-inflammatoire non stéroïdien était signalée par 18 patients (25,7%). Les choux (74,3%) et la laitue (62,9%), aliments à consommer avec modération, étaient les plus cités.

Conclusion

Les connaissances des patients sur la gestion des AVK étaient fragmentaires et insuffisantes pour assurer la sécurité et l'efficacité du traitement. La création d'un programme d'éducation thérapeutique sur les AVK s'avère alors nécessaire.

Anticoagulation Management of Atrial Fibrillation: The Relationship of Prevailing Adherence to a Dose Protocol and Recall Schedule on TTR in Primary Care

Objective:

To investigate the prevailing level of adherence to a dosing algorithm and a recall schedule and its relationship with the time in therapeutic range (TTR) among patients with atrial fibrillation.

Methods:

The study was carried out at a regional primary care clinic in Malaysia. Patients on anticoagulation therapy aged older than 18 years were included in the study. The participants have received continuation of their anticoagulation therapy at the primary care clinic for at least 6 months to 1 year after being discharged from a tertiary center. Correlation and multiple regression studies were performed to determine the significance of the predictors of TTR.

Results:

A majority (217) of patients with atrial fibrillation received anticoagulation therapy at the clinic followed by patients with mitral valve replacement and aortic valve replacement. The mean TTR for patients with atrial fibrillation was 57.6%. General practitioners (GPs) adhered to 75.5% of the dose protocol but fared poorly in adhering to the recall schedule (36.2%). The concordance to the dose algorithm and recall schedule were significantly related to TTR. Multiple regression analysis proved that the concordance to the dose algorithm and recall schedule were important predictors of the level of TTR in patients with atrial fibrillation.

Discussion:

The study provides preliminary evidence on the relationship between a validated dose algorithm that is integrated with a recall schedule in the control of TTR in patients with atrial fibrillation on anticoagulation treatment. A larger multicenter study is needed to confirm the results of this finding.

Efficacy and safety of apixaban compared with warfarin regarding time within the therapeutic range

Prevention of thromboembolism by lifelong anticoagulation is an important therapeutic goal in patients with atrial fibrillation according to recent guidelines. Major drawback of vitamin K antagonists are their narrow therapeutic range and interactions with other drugs and food. These have significant impact on the pharmacokinetics and pharmacodynamics requiring regular measurements of the international normalized ratio. Efficiency of the anticoagulant therapy depends considerably on time within the therapeutic range of prothrombin international normalized ratio. Time within the therapeutic range represents the percentage of time within the required range of prothrombin international normalized ratio. Prothrombin international normalized ratio outside the therapeutic range increases the risk of thromboembolism or bleeding according to whether it falls below or above the range. New oral anticoagulants do not require routine monitoring of anticoagulation. Their efficacy and safety are shown to be at least as good as or better than those of warfarin. In patients with nonvalvular atrial fibrillation ARISTOTLE study revealed that antithrombotic effect of apixaban compared with warfarin is better and with lower bleeding risk irrespective of the quality of prothrombin international normalized ratio control. Orv. Hetil., 2014, 155(5), 177–181.

Improvement of anticoagulant treatment using a dynamic decision support algorithm: a Danish Cohort study

INTRODUCTION

Warfarin is the most widely prescribed vitamin K antagonist and in the United States and Europe more than 10 million people are currently in long-term oral anticoagulant treatment. This study aims to retrospectively validate a dynamic statistical model providing dosage suggestions to patients in warfarin treatment.

MATERIALS AND METHODS

The model was validated on a cohort of 553 patients with a mean TTR of 83%. Patients in the cohort were self-monitoring and managed by a highly specialised anticoagulation clinic. The predictive model essentially consists of three parts handling INR history, warfarin dosage and biological noise, which allows for prediction of future INR values and optimal warfarin dose to stay on INR target. Further, the model is based on parameters initially being set to population values and gradually individualised during monitoring of patients.

PRIMARY OUTCOME

Time in therapeutic range was used as surrogate quality measure of the treatment, and model-suggested dosage of warfarin was used to assess the accuracy of the model performance.

RESULTS

The accuracy of the model predictions measured as median absolute error was 0.53 mg/day (interquartile range from 0.25 to 1.0). The model performance was evaluated by the difference between observed and predicted warfarin intake in the preceding week of an INR measurement. In more than 70% of the cases where INR measurements were outside the therapeutic range, the model suggested a more reasonable dose than the observed intake.

CONCLUSION

Applying the proposed dosing algorithm can potentially further increase the time in INR target range beyond 83%.

Postdischarge international normalized ratio testing and long-term clinical outcomes of patients with heart failure receiving warfarin: findings from the ADHERE registry linked to Medicare claims

BACKGROUND

Effective warfarin thromboprophylaxis requires maintaining anticoagulation within the recommended international normalized ratio (INR) range. INR testing rates and associations between testing and outcomes are not well understood.

HYPOTHESIS

INR testing rates after hospitalization for acute decompensated heart failure are suboptimal, and testing is associated with lower risks of mortality and adverse clinical events.

METHODS

We conducted a retrospective cohort study of patients who were long-term warfarin users and were hospitalized for heart failure, had a medical history of atrial fibrillation or valvular heart disease, and were enrolled in fee-for-service Medicare. INR testing was defined as ≥1 outpatient INR test within 45 days after discharge. Using Cox proportional hazards models, we examined associations between testing and all-cause mortality, all-cause readmission, and adverse clinical events at 1 year.

RESULTS

Among 8558 patients, 7722 (90.2%) were tested. After 1 year, tested patients had lower all-cause mortality (23.5% vs 32.6%; P < 0.001) and fewer myocardial infarctions (2.0% vs 3.3%; P = 0.02). These differences remained significant after multivariable adjustment with hazard ratios of 0.72 (95% confidence interval [CI]: 0.63-0.84; P < 0.001) and 0.58 (95% CI: 0.41-0.83; P = 0.003), respectively. Differences in all-cause readmission, thromboembolic events, ischemic stroke, and bleeding events were not statistically significant.

CONCLUSIONS

Postdischarge outpatient INR testing in patients with heart failure complicated by atrial fibrillation or valvular heart disease was high. INR testing was associated with improved survival and fewer myocardial infarctions at 1 year but was not independently associated with other adverse clinical events.

Drug adherence in patients taking oral anticoagulation therapy

Oral anticoagulation has proven to reduce mortality and morbidity of thromboembolic events. One of the most important determinants of the effectiveness and safety of anticoagulation therapy is the adherence to the prescribed therapy. Vitamin K antagonists are characterized by under-utilization, a narrow therapeutic window and multiple food and drug interactions which contribute to a variable dose-response relationship with the risk of insufficient protection and/or increased bleeding risk. The "new" direct oral anticoagulants have demonstrated equal or superior protection and reduced bleeding risks compared to warfarin and are easier to use because of fixed dosing without monitoring of anticoagulation. Controlling of adherence to the direct oral anticoagulants is difficult. Therefore, continuous and regular medication intake represents a pre-requisite for achieving optimal protection. The present review aims to give an overview about the factors that affect drug adherence in patients taking oral anticoagulation drugs and discusses strategies to improve drug adherence.

Transitions of care in anticoagulated patients

Anticoagulation is an effective therapeutic means of reducing thrombotic risk in patients with various conditions, including atrial fibrillation, mechanical heart valves, and major surgery. By its nature, anticoagulation increases the risk of bleeding; this risk is particularly high during transitions of care. Established anticoagulants are not ideal, due to requirements for parenteral administration, narrow therapeutic indices, and/or a need for frequent therapeutic monitoring. The development of effective oral anticoagulants that are administered as a fixed dose, have low potential for drug-drug and drug-food interactions, do not require regular anticoagulation monitoring, and are suitable for both inpatient and outpatient use is to be welcomed. Three new oral anticoagulants, the direct thrombin inhibitor, dabigatran etexilate, and the factor Xa inhibitors, rivaroxaban and apixaban, have been approved in the US for reducing the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation; rivaroxaban is also approved for prophylaxis and treatment of deep vein thrombosis, which may lead to pulmonary embolism in patients undergoing knee or hip replacement surgery. This review examines current options for anticoagulant therapy, with a focus on maintaining efficacy and safety during transitions of care. The characteristics of dabigatran etexilate, rivaroxaban, and apixaban are discussed in the context of traditional anticoagulant therapy.

Clinical validation of a new algorithm for computerized dosing of vitamin K antagonist therapy: a retrospective simulation study

The number of patients on oral anticoagulant therapy has increased in recent years, and this trend is expected to continue. The increased workload for physicians has led to the development of computerized systems to make organizational workflow more efficient. These programs may include algorithms to propose a weekly dosage and timing for the following visit. Before introducing a new algorithm in clinical practice, its safety and efficacy must be validated. We undertook a retrospective simulation study to test a new algorithm for the TAOnet system. The main outcome was the percentage of concordant and discordant proposals between manual- and algorithm-based prescriptions. Pairs of computerized and physician prescriptions were assessed. They were categorized as 0.1-5, 5.1-10 and >10% if the dose was different, and assigned as "algorithm better" or "manual better" dependent upon the subsequent international normalized ratio value. In 61.0% of cases, the manual and computerized weekly dosage assignments were identical; in 15.3% of cases, the difference was between 0.1 and 5%; in 14.7 of cases, it was between 5.1 and 10%; and in 9.0% of cases, it was >10%. The algorithm did better in 43.9% of discordant pairs, generally due to less frequent under-dosing. In conclusion, the new algorithm proved to consistently overlap with the manual method. The algorithm is useful but must be tested in a multi-center, prospective, interventional study.

Evaluation of a Pharmacist-Managed Anticoagulation Clinic

Background

Anticoagulation therapy is important in the prevention and treatment of cardioembolic events. Warfarin is frequently used but requires continual monitoring to ensure safety and efficacy. The target time in therapeutic range (TTR) is not always achieved.

Objectives

The objectives for this study were to determine the TTR for a pharmacist-managed anticoagulation clinic and identify reasons for sub- and supratherapeutic international normalized ratio (INR) values.

Methods

Medical records for subjects prescribed warfarin were reviewed. Demographic and relevant clinical information was assessed. INR measurements were extracted for subjects enrolled. The TTR was calculated, and the cause for sub- or supratherapeutic values was determined when possible.

Results

One hundred twenty-six subjects were included in this retrospective study. The calculated TTR was 51%. The cause for more than 65% of the sub- and supratherapeutic INR values could not be determined. One subject incurred a clot and 6 subjects suffered a bleed. No deaths occurred. Age was the only factor that correlated with a supratherapeutic INR value ( r = −0.179, P = .045).

Conclusion

Pharmacists in the anticoagulation clinic are effectively managing patients who are taking warfarin by frequently maintaining INR values near or within the recommended therapeutic range. Very few negative outcomes occurred during the time of study.

Benchmark for time in therapeutic range in venous thromboembolism: a systematic review and meta-analysis

INTRODUCTION

The percentage of time within the target INR range 2.0 to 3.0 (TTR) in patients treated with vitamin K antagonists varies considerably among efficacy-studies of novel anticoagulants. In order to properly asses the quality of anticoagulant control in upcoming cost-effectiveness studies and real life registries this systematic review reports a benchmark of TTR for different treatment durations in patients with venous thromboembolism and discusses ways to calculate TTR.

METHODS

Medline and Embase were searched for studies published between January 1990 and May 2012. Randomized controlled trials and cohort studies reporting the TTR in patients with objectively confirmed venous thromboembolism treated with vitamin K antagonists (VKA) were eligible. Duplicate reports, studies only reporting INR during initial treatment or with VKA treatment less than 3 months were excluded. Three authors assessed trials for inclusion and extracted data independently. Discrepancies were resolved by discussion between the reviewers. A meta-analysis was performed by calculating a weighted mean, based on the number of participants in each included study, for each time-period in which the TTR was measured since the confirmation of the diagnosis of VTE.

RESULTS

Forty studies were included (26064 patients). The weighted means of TTR were 54.0% in the first month since the start of treatment, 55.6% in months 1 to 3, 60.0% in months 2 to 3, 60.0% in the months 1 to 6+ and 75.2% in months 4 to 12+. Five studies reported TTR in classes. The INR in these studies was ≥ 67% of time in therapeutic range in 72.0% of the patients.

CONCLUSION

Reported quality of VKA treatment is highly dependent on the time-period since the start of treatment, with TTR ranging from approximately 56% in studies including the 1(st) month to 75% in studies excluding the first 3 months.

Electronic health record-based monitoring of primary care patients at risk of medication-related toxicity

BACKGROUND

Timely laboratory monitoring may reduce the potential harm associated with chronic medication use. A study was conducted to determine the proportion of patients receiving National Committee for Quality Assurance (NCQA)-recommended laboratory medication monitoring in a primary care setting and to assess the effect of electronic health record (EHR)-derived, paper-based, provider-specific feedback bulletins on subsequent patient receipt of medication monitoring.

METHODS

In a single-arm, pre-post intervention in two federally qualified community health centers in Baltimore, patients targeted were adults prescribed at least 6 months (in the preceding year) for at least one index medication (digoxin, statins, diuretics, angiotensin-converting enzyme inhibitors/ angiotensin II-receptor blockers) in a 12-month period (August 2008-July 2009).

RESULTS

Among the 2,013 patients for whom medication monitoring was recommended, 42% were overdue for monitoring at some point during the study. As the number of index medications the patient was prescribed increased, the likelihood of ever being overdue for monitoring decreased. Being listed on the provider-specific monitoring bulletin doubled the odds of a patient receiving recommended laboratory monitoring before the next measurement period (1-2 months). Limiting the intervention to the most overdue patients, however, mitigated its overall impact.

CONCLUSIONS

Recommended laboratory monitoring of chronic medications appears to be inconsistent in primary care, resulting in potential harm for individuals at risk for medication-related toxicity. EHRs may be an important component of systems designed to improve medication monitoring, but multimodal interventions will likely be needed to achieve high reliability.

The benefits of pharmacist-delivered warfarin education in the home

Objectives

Good warfarin knowledge is important for optimal patient outcomes, but barriers exist to effective education and warfarin knowledge is often poor. This study aimed to explore the educational outcomes of home-based warfarin education provided by trained pharmacists.

Methods

In a prospective, non-randomised, controlled cohort trial, patients received either usual community-based post-discharge care or a post-discharge warfarin management service, including warfarin education by trained pharmacists during two or three home visits. Patients’ warfarin knowledge was assessed at 8 and 90 days post-discharge using the Oral Anticoagulation Knowledge test.

Key findings

One hundred and thirty-nine patients were recruited into the usual care group between November 2008 and August 2009, and 129 into the intervention group between May and December 2009. Pharmacist-delivered warfarin education was associated with a significant difference between the intervention patients’ baseline and day 8 mean warfarin knowledge scores of 64.5% (95% confidence interval (CI) 61.0–68.5%) and 78.0% (95% CI 74.5–81.5%; P &lt; 0.001), respectively. The intervention patients also scored significantly higher than the usual care patients at day 8 (65.0%, 95% CI 61.5–68.0%; P &lt; 0.001), but not at day 90.

Conclusions

Use of an existing healthcare framework overcame several systemic barriers by facilitating warfarin education in patients’ homes. While the intervention was associated with better short-term warfarin knowledge, follow-up may be required to optimise its benefits. Widespread implementation of home-based warfarin education by pharmacists has the potential to contribute significantly to improved outcomes from warfarin therapy.

Natural Health Product Utilization in Warfarinized Children; Prevalence and Knowledge

Background:

The need for long-term thromboprophylaxis in children using warfarin therapy is increasing. Natural health products (NHPs) are administered to children by parents who perceive them to be useful and acceptable adjuncts or alternatives to conventional therapies. Interactions of NHPs with prescribed therapies may result in serious adverse events. NHP usage is underevaluated in children and there are no studies evaluating NHP usage in warfarinized children.

Objectives:

To explore NHP use in warfarinized children and their siblings to determine the prevalence, varieties, and reasons for NHP usage, as well as the potential effect on warfarinization (eg, time in therapeutic range [TTR]).

Methods:

This is a 3-phase cross-sectional cohort study that includes the (1) prevalence (2) NHP education and knowledge assessment, and (3) the follow-up NHP utilization phase.

Results:

Forty-six percent of warfarinized children consumed NHPs, with time in therapeutic range of 74%. The mean score for baseline knowledge of NHPs and warfarin following the education phase was 67%. Follow-up NHP use was 30%, and increased consistency of utilization with TTR was 83% (p < 0.05), consistent with education provided.

Conclusions:

The consistent prevalence rates over time of NHP usage in warfarinized children indicate the need for future studies. Education remains vital to combat the potential risks of NHP-warfarin interaction, encouraging patient disclosure and consistency.