Variability of INR and its relationship with mortality, stroke, bleeding and hospitalisations in patients with atrial fibrillation

Association between gene polymorphisms and initial warfarin therapy in patients after heart valve surgery

BACKGROUND

Warfarin is widely used for the prevention and treatment of thrombotic events. This study aimed to examine the influence of gene polymorphisms on the early stage of warfarin therapy in patients following heart valve surgery.

METHODS

Nine single nucleotide polymorphisms were genotyped using microarray chips, categorizing patients into three groups: normal responders (Group I), sensitive responders (Group II), and highly sensitive responders (Group III). The primary clinical outcomes examined were time in therapeutic range (TTR) and international normalized ratio (INR) variability. To investigate potential influencing factors, a generalized linear regression model was employed.

RESULTS

Among 734 patients, the prevalence of CYP2C9*3-1075A > C, CYP2C19*3-636G > A, and CYP2C19*17-806C > T variants were 11.2%, 9.9%, and 1.9% of patients, respectively. VKORC1-1639G > A or the linked -1173C > T variant was observed in 99.0% of the patients. Generalized linear model analysis revealed an impact of sensitivity grouping on INR variability. Compared to Group I, Group II showed higher TTR values (p = 0.023), while INR variability was poorer in Group II (p < 0.001) and Group III (p < 0.001). Individual gene analysis identified significant associations between CYP2C9*3-1075A > C (p < 0.001), VKORC1-1639G > A or the linked -1173 C > T (p = 0.009) and GGCX-3261G > A (p = 0.019) with INR variability.

CONCLUSION

The genotypes of CYP2C9, VKORC1, and GGCX were found to have a significant impact on INR variability during the initial phase of warfarin therapy. However, no significant association was observed between TTR and gene polymorphisms. These findings suggest that focusing on INR variability is crucial in clinical practice, and preoperative detection of gene polymorphisms should be considered to assist in the initiation of warfarin therapy.

Elevated International Normalized Ratio and Mortality in Hospitalized Patients Treated with Direct Oral Anticoagulants

BACKGROUND

Direct oral anticoagulants (DOACs) are associated with a prolongation of the prothrombin time and an increased international normalized ratio (INR). The clinical significance of these changes is unclear. This study aimed to examine the association between an elevated INR on admission and in-hospital death and long-term survival in patients treated with DOACs.

METHODS

Data were retrospectively retrieved from records of hospitalized patients at the Sheba Medical Center between November 2008 and July 2023. Patients were selected based on DOAC treatment, coagulation profile, and INR test done within 48 hours of hospitalization. The outcomes were in-hospital mortality and mortality in the year following hospitalization.

RESULTS

The study included 11,399 hospitalized patients treated with DOACs. Patients with elevated INR had a 180% higher risk of in-hospital mortality (adjusted odds ratio 2.80; 95% confidence interval, 2.30-3.39) and a 57% increased risk of death during the following year (adjusted hazard ratio 1.57; 95% confidence interval, 1.44-1.71). Similar results were observed in subgroup analyses for each DOAC.

CONCLUSIONS

An elevated INR on admission is associated with a higher risk for in-hospital death and increased risk for mortality during the first year following hospitalization in hospitalized patients treated with DOACs. This highlights that elevated INR levels in patients on DOACs should not be dismissed as laboratory variations due to DOAC treatment, as they may serve as a prognostic marker.

The association between prothrombin time-international normalized ratio and long-term mortality in patients with coronary artery disease: a large cohort retrospective study with 44,662 patients

BACKGROUND

The association between prothrombin time-international normalized ratio (PT-INR) and long-term prognosis among patients with coronary artery disease (CAD) without atrial fibrillation or anticoagulant therapy was still unclear. We analyzed the association of PT-INR levels and long-term mortality in a large cohort of CAD patients without atrial fibrillation or using of anticoagulant drugs.

METHODS

We obtained data from 44,662 patients who were diagnosed with CAD and had follow-up information from January 2008 to December 2018. The patients were divided into 4 groups (Quartile 1: PT-INR ≤ 0.96; Quartile2: 0.96 < PT-INR ≤ 1.01; Quartile3: 1.01 < PT-INR ≤ 1.06; Quartile4: PT-INR > 1.06). The main endpoint was long-term all-cause death. Kaplan-Meier curve analysis and Cox proportional hazards models were used to investigate the association between quartiles of PT-INR levels and long-term all-cause mortality.

RESULTS

During a median follow-up of 5.25 years, 5613 (12.57%) patients died. We observed a non-linear shaped association between PT-INR levels and long-term all-cause mortality. Patients in high PT-INR level (Quartile4: PT-INR > 1.06) showed a significantly higher long-term mortality than other groups (Quartile2 or 3 or 4), (Compared with Quartile 1, Quartile 2 [0.96 < PT-INR ≤ 1.01], aHR = 1.00, 95% CI 0.91-1.00, P = 0.99; Quartile 3 [1.01 < PT-INR ≤ 1.06], aHR = 1.10, 95% CI 1.01-1.20, P = 0.03; Quartile 4 [PT-INR > 1.06], aHR = 1.33, 95% CI 1.22-1.45, P < 0.05).

CONCLUSIONS

Our study demonstrates high levels of PT-INR were associated with an increased risk of all-cause mortality.

Increased rebleeding and mortality in patients with gastrointestinal bleeding treated with anticoagulant drugs compared to antiplatelet drugs

BACKGROUND/AIM

We determined the effect of antiplatelet and anticoagulant agents on rebleeding and mortality in patients with gastrointestinal bleeding.

METHODS

This was a prospective study of patients admitted with gastrointestinal bleeding between 2013 and 2018. Outcomes were compared among patients on antiplatelet agents only, anticoagulant drugs only, combination therapy, and none. The association between mortality, rebleeding, and type of antithrombotic medication on admission and discharge was determined using multivariate analysis.

RESULTS

A total of 509 patients were followed up for a median of 19 months. End of follow-up rebleeding and mortality rates were 19.4% and 23.0%, respectively. Independent predictors of mortality were age [hazard ratio (HR) = 1.025 per year increase, P = 0.002], higher Charlson Comorbidity Index (HR = 1.4, P < 0.0001), severe bleeding (HR = 2.1, P < 0.0001), and being on anticoagulants (HR = 2.3, P = 0.002). Being on antiplatelets was protective against rebleeding (HR = 0.6, P = 0.047). Those on anticoagulants were more likely to die (HR = 2.5, P < 0.0001) and to rebleed (HR = 2.1, P = 0.01) than those on antiplatelets. Antithrombotic drug discontinuation upon discharge was associated with increased mortality in patients with cardiovascular disease.

CONCLUSION

In gastrointestinal bleeding, rebleeding and mortality were associated with being on anticoagulant drugs, while being on antiplatelet agents was protective against rebleeding. Discontinuation of antithrombotics upon discharge increased the risk of death. The findings inform risk stratification and decisions regarding continuation or discontinuation of antithrombotics.

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.

Usefulness of International Normalized Ratio to Albumin Ratio for Evaluation of Mortality in Hepatitis B Virus-Associated Decompensated Cirrhosis

Background

We sought to determine the prognostic value of prothrombin time-international normalized ratio to albumin ratio (PTAR) in patients with hepatitis B virus-associated decompensated cirrhosis (HBV-DeCi).

Methods

The study enrolled 166 HBV-DeCi patients. Multivariate regression analysis was performed to identify predictors associated with mortality.

Results

Among the 166 HBV-DeCi patients, 27 (16.3%) had died by 30 days after admission. PTAR was markedly increased in nonsurvivors compared with survivors, and had a significant positive correlation with disease severity. Multivariate analysis identified PTAR as an effective independent predictor for mortality in HBV-DeCi patients.

Conclusions

High PTAR was associated with poor outcomes and can act as a novel prognostic predictor for mortality in HBV-DeCi patients.

Outcomes related to anticoagulation management for mechanical valve replacements

Background

This study evaluates anticoagulation management and its impact on longitudinal clinical outcomes in patients undergoing mechanical valve replacement.

Methods

Patients undergoing mechanical mitral valve replacement (MVR) or aortic valve replacement (AVR) from 2010–2018 at a single center were included. Patients were stratified into therapeutic and non-therapeutic anticoagulation groups based on the median percentage of international normalized ratio (INR) values within the reference range (2.0–3.0 for AVR, 2.5–3.5 for MVR) during the first post-operative year. Using Cox regression analysis, comorbidity-adjusted survival and freedom from adverse events were compared.

Results

Six hundred and fifty-one patients underwent mechanical valve replacement (166 MVR, 485 AVR). Comorbidity-adjusted survival was similar in the MVR and AVR cohorts (P=0.23). There was a median of 27 [interquartile range (IQR): 14–42] INRs drawn per patient in the first post-operative year. The median percentage of INRs within the reference values during the first post-operative year was 42.85% (IQR: 30.77–53.95%), with the majority of non-therapeutic INRs being subtherapeutic (34.51%; n=6,864). There were no significant differences in adjusted survival between the therapeutic and non-therapeutic groups [hazard ratio (HR): 1.12, P=0.73]. Within the first post-operative year, there were no significant differences in stroke, major bleeding, peripheral non-stroke arterial thromboembolism, and readmission for intravenous heparin in the therapeutic and non-therapeutic groups.

Conclusions

Taking into account relevant comorbidities and valve type, patients with a larger proportion of non-therapeutic INRs during the first post-operative year demonstrated no difference in longitudinal clinical outcomes. Further research into more standardized INR monitoring and potentially expanded INR target ranges for patients undergoing mechanical valve replacement is warranted.

Effect of switching from acenocoumarol to phenprocoumon on time in therapeutic range and INR variability: A cohort study

Background

Treatment with vitamin K antagonists (VKA) requires a high proportion of time in the therapeutic range (TTR) and a low international normalised ratio (INR) variability to be maximally safe and effective. Switching from short-acting acenocoumarol to long-acting phenprocoumon could improve VKA control.

Aims

We assessed whether switching from acenocoumarol to phenprocoumon improves the time in the therapeutic range (TTR) and INR variability.

Methods and results

In a retrospective cohort with data on 236,957 patients-years of VKA management from two first-line anticoagulation clinics in the Netherlands, we identified 124 patients in target range 2–3, 269 patients in target range 2–3.5 and 98 patients in target range 2.5–3.5 who switched from acenocoumarol to phenprocoumon. They were matched in a 1:2 ratio to non-switching controls using propensity score matching. Over the first 180 days after a switch, switchers’ TTR declined 5 (95% CI 1 to 10), 10 (95% CI 7 to 13) and 5 (95% CI 0 to 11) percentage points relative to non-switchers, in target ranges 2–3, 2–3.5 and 2.5–3.5. Anticoagulation was more often supra-therapeutic in switchers, and switchers had a higher INR variability. In the following 180 days, TTR in switchers became 1 (95% CI -4 to 6), 4 (95% CI 0 to 7) and 6 (95% CI 1 to 12) percentage points better than in non-switchers. Switchers’ INRs were much more stable than non-switchers’.

Conclusion

Eventually, a switch from acenocoumarol to phenprocoumon leads to a higher TTR and a lower INR variability. However, this is preceded by a transition period with opposite effects. An improved conversion algorithm could possibly shorten the transition period. Until then, physicians and patients should decide whether switching is worth the increased risk during the transition phase.

Revisiting the International Normalized Ratio Threshold for Bleeding Risk and Mortality in Primary Total Hip Arthroplasty: A National Surgical Quality Improvement Program Analysis of 17,567 Patients

BACKGROUND

Efforts to identify preoperative risk factors for primary total hip arthroplasty have amplified with its increasing incidence. The international normalized ratio (INR) is 1 measure that may influence postoperative outcomes. This study of a national database assessed whether there exists an association between preoperative INR and postoperative bleeding and mortality among patients who underwent primary total hip arthroplasty.

METHODS

We retrospectively analyzed 17,567 adult patients who underwent primary total hip arthroplasty in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) between 2005 and 2016. Patients were stratified by preoperative INR into 4 groups: INR <1.0, 1.0 to <1.25, 1.25 to <1.5, and ≥1.5. Bleeding necessitating transfusion was the primary outcome, and secondary outcomes included mortality, infection, and readmission. Multivariable logistic regressions controlled for baseline differences.

RESULTS

Among the patients who underwent total hip arthroplasty, 20.5% had INR <1.0, 73.6% had INR 1.0 to <1.25, 4.2% had INR 1.25 to <1.5, and 1.8% had INR ≥1.5. Mortality increased incrementally from 0.3% for INR <1.0 to 4.9% for INR ≥1.5 (p < 0.001), and bleeding risk increased from 13.2% for INR <1.0 to 29.3% for INR ≥1.5 (p < 0.001). After adjustment, bleeding risk was increased for INR 1.25 to <1.5 (odds ratio [OR], 1.55 [95% confidence interval (CI), 1.26 to 1.92]) and INR ≥1.5 (OR, 1.55 [95% CI, 1.15 to 2.08]) compared with INR <1.0. The only group associated with increased mortality was INR ≥1.5 (OR, 2.69 [95% CI, 1.07 to 6.76]). The length of stay significantly increased with increasing INR, from 3.6 to 6.3 days (p < 0.001).

CONCLUSIONS

This study found a significant, independent effect between increased preoperative INR and increased bleeding and mortality. Bleeding risk becomes evident at INR ≥1.25, and those patients with INR ≥1.5 are at significantly increased risk of mortality.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The association of high-normal international-normalized-ratio (INR) with mortality in patients referred for coronary angiography

Aims

The international-normalized-ratio (INR) is typically used to monitor patients on warfarin or related oral anticoagulant therapy. The aim of our study was to investigate the association of the INR with mortality in coronary artery disease (CAD) patients not on oral anticoagulant therapy.

Methods and results

Between 1997 to 2000 the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study enrolled 3316 patients of German ancestry that had been referred for coronary angiography. We excluded patients on coumarin therapy (n = 222) and patients with an INR more than 5 standard deviations (SD) away from the mean (n = 30). During a median follow-up of 9.9 years, 884 patients died, 547 patients from cardiovascular causes. After adjustment for cardiovascular risk factors the INR was associated with all-cause mortality in all patients and the CAD positive group with HRs (95% CI) of 1.14(1.07–1.21) and 1.16(1.09–1.23) per 1-SD increase, respectively. Adjustment for NT-proBNP rendered the association insignificant.

Conclusion

In LURIC, the INR was positively associated with mortality in patients with prevalent CAD not on oral anticoagulant therapy as well as in patients without CAD. Adjustment for NT-proBNP abolished the association suggesting clinical or subclinical heart failure strongly contributing to increased INR and higher mortality.

Control of Anticoagulation Therapy in Patients with Atrial Fibrillation Treated with Warfarin: A Study from the Chinese Atrial Fibrillation Registry

Background

Several factors determine the efficacy of warfarin anticoagulation in patients with non-valvular atrial fibrillation (NVAF). This study aimed to use data from the Chinese Atrial Fibrillation Registry study to assess the control of anticoagulation therapy in Chinese patients with NVAF treated with warfarin.

Material/Methods

From the Chinese Atrial Fibrillation Registry study the anticoagulant use and dosing, the time in therapeutic range (TTR) of the international normalized ratio (INR), and standard deviation of the observed INR values (SD_INR), and their influencing factors were evaluated.

Results

The median INR and SD_INR were 2.04 (IQR 1.71–2.41) and 0.50 (IQR, 0.35–0.69), respectively. The median TTR was 51.7% (IQR, 30.6–70.1%) and only 25.1% had a TTR ≥70%. Age was ≥70 years (OR, 0.72; 95% CI, 0.55–0.94; P=0.015), bleeding history (OR 0.48; 95% CI, 0.23–0.89; P=0.029), the use of a single drug (OR, 0.62; 95% CI, 0.42–0.92; P=0.016), more than drug (OR, 0.60; 95% CI, 0.41–0.88; P=0.009), and lack of assessment of bleeding risk (OR, 0.72; 95% CI, 0.54–0.97; P=0.033) were associated with TTR <70% (INR 2.0–3.0). Coronary heart disease (CHD) and peripheral artery disease (PAD) (OR, 0.69; 95% CI, 0.52–0.90; P=0.007) and diabetes mellitus (OR, 0.79; 95% CI, 0.62–0.99; P=0.044) were associated with increased variability in INR (SD_INR ≥0.5).

Conclusions

In Chinese patients with NVAF, warfarin anticoagulation was associated with lower TTR and less stable anticoagulation than in current guidelines, and risk factors for reduced safety and efficacy were identified.

Predicting Thromboembolic and Bleeding Event Risk in Patients with Non-Valvular Atrial Fibrillation: A Systematic Review

BACKGROUND

 Atrial fibrillation (AF) is a common cardiac arrhythmia that increases the risk of stroke. Medical therapy for decreasing stroke risk involves anticoagulation, which may increase bleeding risk for certain patients. In determining the optimal therapy for stroke prevention for patients with AF, clinicians use tools with various clinical, imaging and patient characteristics to weigh stroke risk against therapy-associated bleeding risk.

AIM

 This article reviews published literature and summarizes available risk stratification tools for stroke and bleeding prediction in patients with AF.

METHODS

 We searched for English-language studies in PubMed, Embase and the Cochrane Database of Systematic Reviews published between 1 January 2000 and 14 February 2018. Two reviewers screened citations for studies that examined tools for predicting thromboembolic and bleeding risks in patients with AF. Data regarding study design, patient characteristics, interventions, outcomes, quality, and applicability were extracted.

RESULTS

 Sixty-one studies were relevant to predicting thromboembolic risk and 38 to predicting bleeding risk. Data suggest that CHADS₂, CHA₂DS₂-VASc and the age, biomarkers, and clinical history (ABC) risk scores have the best evidence for predicting thromboembolic risk (moderate strength of evidence for limited prediction ability of each score) and that HAS-BLED has the best evidence for predicting bleeding risk (moderate strength of evidence).

LIMITATIONS

 Studies were heterogeneous in methodology and populations of interest, setting, interventions and outcomes analysed.

CONCLUSION

 CHADS₂, CHA₂DS₂-VASc and ABC scores have the best prediction for stroke events, and HAS-BLED provides the best prediction for bleeding risk. Future studies should define the role of imaging tools and biomarkers in enhancing the accuracy of risk prediction tools.

PRIMARY FUNDING SOURCE

 Patient-Centered Outcomes Research Institute (PROSPERO #CRD42017069999).

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.

Differences among western European countries in anticoagulation management of atrial fibrillation

Due to improved implementation of guidelines, new scoring approaches to improve risk categorisation, and introduction of novel oral anticoagulants, medical management of patients with atrial fibrillation (AF) is continuously improving. The PREFER in AF registry enrolled 7,243 consecutive patients with ECG-confirmed AF in seven European countries in 2012–2013 (mean age: 71.5 ± 10.7 years; 60.1% males; mean CHA2DS 2 -VASc score: 3.4). While patient characteristics were generally homogeneous across countries, anticoagulation management showed important differences: the proportion of patients taking vitamin K antagonists (VKAs) varied between 86.0% (in France) and 71.4% (in Italy). Warfarin was used predominantly in the UK and Italy (74.9% and 62.0%, respectively), phenprocoumon in Germany (74.1%), acenocoumarol in Spain (67.3%), and fluindione in France (61.8 %). The major sites for international normalised ratio (INR) measurements were biology laboratories in France anticoagulation clinics in Italy, Spain, and the UK, and physicians’ offices or self-measurement in Germany. Temporary VKA discontinuation and bridging with other anticoagulants was frequent (at least once in the previous 12 months for 22.9% of the patients, on average; ranging from 29.7% in Germany to 14.9% in the UK). Time in therapeutic range (TTR), defined as at least two of the last three available INR values between 2.0–3.0 prior to enrolment, ranged from 70.3% in Spain to 81.4% in Germany. TTR was constantly overestimated by physicians. While the type and half-lives of VKA as well as the mode of INR surveillance differed, overall quality of anticoagulation management by TTR was relatively homogenous in AF patients across countries.

[Stroke prevention in atrial fibrillation in Germany. Situational analysis of treatment reality based on retrospective data]

BACKGROUND

Guideline-based, risk-adjusted therapy with anticoagulants reduce thromboembolic stroke risk in patients with atrial fibrillation (AF).

METHOD

This study analyzed use of oral anticoagulation in German AF-patients. Access to anonymized patient records was made via IMS Health Disease Analyzer database (sample size: 113,619 patients with ICD-10 Code I48.-; observation period: 11/2010-10/2013). Results were subsequently extrapolated to all general practitioners' (GPs) and cardiological practices in Germany.

RESULTS

In 2011 12-month AF-prevalence was extrapolated to 2.1 million patients (first diagnosed: n = 537.548). In 2012 AF-prevalence gone up to 2.2 million cases (first diagnosed: n = 537.548) and in 2013 to 2.8 million (first diagnosed: n = 636.571). Commonly prescribed oral anticoagulants (OAC) were vitamin K antagonists (VKA). Unstable INR setting, private health insurance, hospital admission, heart failure or hypertension increased probability of change from VKA to non-vitamin K antagonist oral anticoagulants (NOAC). 17.3-36.5% of patients with CHA₂DS₂-VASc-score ≥ 2 did not receive any thromboembolism prophylaxis; 38.5% with CHA₂DS₂-VASc-score = 0 received unnecessarily OACs. For 2013 a potential of 29.749 ischemic strokes in GP practices was calculated, which possibly can be avoided by thromboembolism prophylaxis according to guidelines.

CONCLUSIONS

Risk-based anticoagulation showed requirements for optimization. Use of OACs, according to guideline recommendations, would minimize bleeding risks, reduce ischemic strokes and could release resources.

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.

Bleeding complications and mortality in warfarin-treated VTE patients, dependence of INR variability and iTTR

High quality of warfarin treatment is important to prevent recurrence of venous thromboembolism (VTE) without bleeding complications. The aim of this study was to examine the effect of individual time in therapeutic range (iTTR) and International Normalised Ratio (INR) variability on bleeding risk and mortality in a large cohort of well-managed patients with warfarin due to VTE. A cohort of 16612 patients corresponding to 19502 treatment periods with warfarin due to VTE between January 1, 2006 and December 31, 2011 was retrieved from the Swedish national quality register AuriculA and matched with the Swedish National Patient Register for bleeding complications and background characteristics and the Cause of death register for occurrence and date of death. The rate of bleeding was 1.79 (confidence interval (CI) 95 % 1.66–1.93) per 100 treatment years among all patients. Those with poor warfarin treatment quality had a higher rate of clinically relevant bleeding, both when measured as iTTR below 70 %, 2.91 (CI 95 % 2.61–3.21) or as INR variability over the mean value 0.85, 2.61 (CI 95 % 2.36–2.86). Among those with both high INR variability and low iTTR the risk of clinically relevant bleeding was clearly increased hazard ratio (HR) 3.47 (CI 95 % 2.89–4.17). A similar result was found for all-cause mortality with a HR of 3.67 (CI 95 % 3.02–4.47). Both a low iTTR and a high INR variability increase the risk of bleeding complications or mortality. When combining the two treatment quality indicators patients at particular high risk of bleeding or death can be identified.

Impact of renal function on ischemic stroke and major bleeding rates in nonvalvular atrial fibrillation patients treated with warfarin or rivaroxaban: a retrospective cohort study using real-world evidence

OBJECTIVES

Renal dysfunction is associated with increased risk of cardiovascular disease and is an independent predictor of stroke and systemic embolism. Nonvalvular atrial fibrillation (NVAF) patients with renal dysfunction may face a particularly high risk of thromboembolism and bleeding. The current retrospective cohort study was designed to assess the impact of renal function on ischemic stroke and major bleeding rates in NVAF patients in the real-world setting (outside a clinical trial).

METHODS

Medical claims and Electronic Health Records were retrieved retrospectively from Optum's Integrated Claims-Clinical de-identified dataset from May 2011 to August 2014. Patients with NVAF treated with warfarin (2468) or rivaroxaban (1290) were selected. Each treatment cohort was stratified by baseline estimated creatinine clearance (eCrCl) levels. Confounding adjustments were made using inverse probability of treatment weights (IPTWs). Incidence rates and hazard ratios of ischemic stroke and major bleeding events were calculated for both cohorts.

RESULTS

Overall, patients treated with rivaroxaban had an ischemic stroke incidence rate of 1.9 per 100 person-years (PY) while patients treated with warfarin had a rate of 4.2 per 100 PY (HR = 0.41 [0.21-0.80], p = .009). Rivaroxaban patients with an eCrCl below 50 mL/min (N = 229) had an ischemic stroke rate of 0.8 per 100 PY, while the rate for the warfarin cohort (N = 647) was 6.0 per 100 PY (HR = 0.09 [0.01-0.72], p = .02). For the other renal function levels (i.e. eCrCl 50-80 and ≥80 mL/min) HRs indicated no statistically significant differences in ischemic stroke risks. Bleeding events did not differ significantly between cohorts stratified by renal function.

CONCLUSIONS

Ischemic stroke rates were significantly lower in the overall NVAF population for rivaroxaban vs. warfarin users, including patients with eCrCl below 50 mL/min. For all renal function groups, major bleeding risks were not statistically different between treatment groups.

Influence of renal function on anticoagulation control in patients with non-valvular atrial fibrillation taking vitamin K antagonists

BACKGROUND AND PURPOSE

Chronic kidney disease (CKD) has been related to poor anticoagulation control and an increased risk of bleeding. This study aims to evaluate the association between impaired renal function (eGFR <60 mL/min/1.73 m² ) and anticoagulation control in patients with non-valvular atrial fibrillation (AF) on vitamin K antagonists (VKA) therapy. We also assessed whether the predictive value of the SAMe-TT₂ R₂ score prevailed for subgroups both with and without CKD.

METHODS

This is an ancillary analysis of 1381 patients from the PAULA study, which was a cross-sectional, retrospective and nationwide multicenter study.

RESULTS

A total of 370 patients had eGFR <60 mL/min/1.73 m² . Anticoagulation control levels progressively worsened across each stage of CKD. Multiple linear regression analysis showed CKD as an independent predictor of time in therapeutic range (TTR). In the subgroup of patients with preserved renal function, female sex, diet affecting INR, polypharmacy and amiodarone were associated with poorer TTR. The SAMe-TT₂ R₂ score had a significant but modest predictive value for TTR<65% (AUC, area under the curve 0.558, P = .002). In the subgroup of patients with CKD, the SAMe-TT₂ R₂ (>2 points) showed no significant predictive capacity for TTR (AUC 0.528, P = .354). The average TTR was similar for both sexes (P = .255), but with a higher percentage of males subjects with TTR ≥65% (P = .013).

CONCLUSION

Chronic kidney disease is associated with poor anticoagulation control in patients with non-valvular AF taking VKA. The SAMe-TT₂ R₂ score was not predictive of poor TTR in the subgroup with CKD, although a modest predictive value for poor TTR was found in those without CKD.

Genetic determinants of variability in warfarin response after the dose-titration phase

OBJECTIVES

Genetic factors contribute considerably toward variability in warfarin dose requirements and are important in the dose-titration phase; their effects on the stability of anticoagulation later in therapy are not known.

METHODS

Using deidentified electronic medical records linked to a DNA-biobank, we studied 140 African-Americans and 943 European-Americans after the warfarin dose-titration phase. We genotyped 12 single nucleotide polymorphisms in genes (CYP2C9, VKORC1, CYP4F2, GGCX, EPHX1, CALU) associated with altered warfarin dose requirements and tested their associations with international normalized ratio variability (INRVAR) and percent time in therapeutic range in European-Americans and African-Americans.

RESULTS

One allele copy of rs2108622 in CYP4F2 was associated with a 15% [95% confidence interval (CI): 1-26, P=0.03] decrease in the median INRVAR in European-Americans. In African-Americans, GGCX variants rs11676382 and rs699664 were associated with 4.16-fold (95% CI: 1.45-11.97, P=0.009) and 1.50-fold (95% CI: 1.07-2.08, P=0.02) changes in the median INRVAR per variant allele copy, respectively; rs11676382 was also significantly associated with a 23.19% (95% CI: 5.89-40.48, P=0.01) decrease in time in therapeutic range. The total variation in INRVAR explained by both clinical factors and rs2108622 was 5.2% for European-Americans. In African-Americans, the inclusion of GGCX variants rs11676382 and rs699664, and the CYP2C9*8 variant rs7900194 explained ∼29% of the variation in INRVAR.

CONCLUSION

The stability of anticoagulation after the warfarin dose-titration phase is differentially affected by variants in CYP4F2 in European-Americans and GGCX loci in African-Americans.

Root Cause Analysis of Adverse Events in an Outpatient Anticoagulation Management Consortium

BACKGROUND

A number of factors can lead to adverse events (AEs) in patients taking warfarin. Performing a root cause analysis (RCA) of serious AEs is one systematic way of determining the causes of these events.

METHODS

Multidisciplinary teams were formed at Michigan Anticoagulation Quality Improvement Initiative (MAQI²) sites with organized anticoagulation management services (AMS). Medical records from patients who suffered serious AEs (major bleed, embolic stroke, venous thromboembolism) were reviewed, and AMS staff were interviewed to determine the root cause using the "5 Whys" technique. More than 600 patients had an AE and underwent screening by trained RNs. Of these, 79 required full review by a multidisciplinary panel. All potential contributing factors (comorbidities, concurrent medications, current protocols) were assessed to determine the main factor that caused the AE.

RESULTS

Full RCA was completed in 79 cases. The main contributing factor was identified in 69/79 (87%) cases. Most identified AEs, 55/69 (80%), were due to patient-specific factors such as comorbidities. Patient-to-provider and provider-to-provider communication accounted for 16/69 (23%) of events and was the second most common cause. Other causes included protocol non-adherence and technology/equipment issues. After each detailed review, the multidisciplinary panel recommended system changes that addressed the primary cause.

CONCLUSION

The majority of severe AEs for patients taking warfarin were related to nonmodifiable patient-related issues. The remaining AEs were primarily due to patient-to-provider and provider-to-provider communication issues. Methods for improving communication need to be addressed, and methods for more effective patient education should be investigated.

The microINR portable coagulometer: analytical quality and user-friendliness of a PT (INR) point-of-care instrument

Regular measurement of prothrombin time as an international normalized ratio PT (INR) is mandatory for optimal and safe use of warfarin. Scandinavian evaluation of laboratory equipment for primary health care (SKUP) evaluated the microINR portable coagulometer (microINR^®) (iLine Microsystems S.L., Spain) for measurement of PT (INR). Analytical quality and user-friendliness were evaluated under optimal conditions at an accredited hospital laboratory and at two primary health care centres (PHCCs). Patients were recruited at the outpatient clinic of the Laboratory of Medical Biochemistry, St Olav's University Hospital, Trondheim, Norway (n = 98) and from two PHCCs (n = 88). Venous blood samples were analyzed under optimal conditions on the STA-R^®Evolution with STA-SPA + reagent (Stago, France) (Owren method), and the results were compared to capillary measurements on the microINR^®. The imprecision of the microINR^® was 6% (90% CI: 5.3-7.0%) and 6.3% (90% CI: 5.1-8.3) in the outpatient clinic and PHCC2, respectively for INR ≥2.5. The microINR^® did not meet the SKUP quality requirement for imprecision ≤5.0%. For INR <2.5 at PHCC2 and at both levels in PHCC1, CV% was ≤5.0. The accuracy fulfilled the SKUP quality goal in both outpatient clinic and PHCCs. User-friendliness of the operation manual was rated as intermediate, defined by SKUP as neutral ratings assessed as neither good nor bad. Operation facilities was rated unsatisfactory, and time factors satisfactory. In conclusion, quality requirements for imprecision were not met. The SKUP criteria for accuracy was fulfilled both at the hospital and at the PHCCs. The user-friendliness was rated intermediate.

Evaluation of a pharmacogenetic-based warfarin dosing algorithm in patients with low time in therapeutic range - study protocol for a randomized controlled trial

Background

Time in therapeutic range (TTR) is a measurement of quality of warfarin therapy and lower TTR values (<50%) are associated with greater risk of thromboembolic and bleeding events. Recently, we developed a pharmacogenetic-based warfarin dosing algorithm specifically calibrated for a Brazilian patient sample. The aims of this study are: to evaluate the impact of a genetic-based algorithm, compared to traditional anticoagulation, in the time to achieve the therapeutic target and in TTR percentage; and to assess the cost-effectiveness of genotype-guided warfarin dosing in a specific cohort of patients with low TTR (<50%) from a tertiary cardiovascular hospital.

Methods/design

This study is a randomized controlled trial in patients (n = 300) with atrial fibrillation with TTR < 50%, based on the last three INR values. At the first consultation, patients will be randomized into two groups: TA group (traditional anticoagulation) and PA group (pharmacogenetic anticoagulation). For the first group, the physician will adjust the dose according to current INR value and, for the second group, a pharmacogenetic algorithm will be used. At the second, third, fourth and fifth consultations (with an interval of 7 days each) INR will be measured and, if necessary, the dose will be adjusted based on guidelines. Afterwards, patients who are INR stable will begin measuring their INR in 30 day intervals; if the patient’s INR is not stable, the patient will return in 7 days for a new measurement of the INR. Outcomes measures will include the time to achieve the therapeutic target and the percentage of TTR at 4 and 12 weeks. In addition, as a secondary end-point, pharmacoeconomic analysis will be carried out. Ethical approval was granted by the Ethics Committee for Medical Research on Human Beings of the Clinical Hospital of the University of São Paulo Medical School.

Discussion

This randomized study will include patients with low TTR and it will evaluate whether a population-specific genetic algorithm might be more effective than traditional anticoagulation for a selected group of poorly anticoagulated patients.

Trial registration

ClinicalTrials.gov, NCT02592980. Registered on 29 October 2015.

Comparison of the Abilities of Summary Measures of International Normalized Ratio Control to Predict Clinically Relevant Bleeding

BACKGROUND

Limited research has compared the measures of summarizing international normalized ratio (INR) control over time. Measures that are more predictive of patient outcomes would be preferred as would those that are easier to calculate and understand.

METHODS AND RESULTS

We examined 676 patients who received long-term warfarin therapy to treat atrial fibrillation: 125 patients who experienced major hemorrhage and 551 matched controls who did not. Patient INR control was characterized using various measures, from simple (proportion of INR values in range) to complex (eg, area under the curve above target range, squared) measures. Conditional logistic regression was used to examine the ability of each measure to predict the outcome of clinically relevant bleeding across quintiles of control. All measures were associated with clinically relevant bleeding to some extent: patients with the poorest control had significantly more bleeding events compared with patients with the best control. The measure most strongly associated with bleeding was a combination of percent time in therapeutic range and INR variability (odds ratio of 4.34, comparing the lowest to the highest quintiles of control). The strongest single predictor was INR variability, followed closely by time in therapeutic range. More computationally complex measures, which had been expected to perform better, were not so strongly associated with bleeding.

CONCLUSIONS

INR variability was the most strongly associated predictor of clinically relevant bleeding followed closely by time in therapeutic range. Using both measures together had an even stronger association. These findings support continued use of INR variability, time in therapeutic range, or both for research and quality assurance efforts.

Improving Anticoagulation Measurement Novel Warfarin Composite Measure

BACKGROUND

Percent time in therapeutic range (TTR) and international normalized ratio (INR) variability both measure warfarin control and are associated with outcomes independently. Here, we examine the advantages of a warfarin composite measure (WCM), which summarizes the 2 when measuring patient outcomes. We also examine how the measure chosen would affect anticoagulation clinic performance rankings.

METHODS AND RESULTS

We constructed WCM using an equally weighted method, adding standardized TTR to standardized log-transformed INR variability using 103 897 warfarin-experienced patients from 100 anticoagulation clinics. We examined the association of WCM with ischemic stroke, major bleeding, and fatal bleeding, using a subset of patients with atrial fibrillation (n=40 404). We divided patients into quintiles based on their level of control for TTR, log INR variability, and WCM. We calculated the hazard ratios for ischemic stroke, major bleeding, and fatal bleeding stratified by these quintiles. WCM hazard ratios for stroke and fatal bleeding showed the largest difference between excellent control and poorest control quintile compared with TTR and log INR variability, but not for major bleeding. In addition, we compared site rankings obtained using each of our 3 performance measures. Kappa scores for identifying outlier and nonoutlier clinics between WCM and its components were moderate (κ=0.56 for TTR and κ=0.62 for log INR variability) but was weak between TTR and log INR variability (κ=0.13).

CONCLUSIONS

WCM produces the largest range of risk for warfarin complications, widening the floor ceiling effects that limit the use of TTR and INR variability as separate measures. Anticoagulation clinics ranking changed considerably according to the anticoagulation measure that was selected.

Effects of anticoagulation provider continuity on time in therapeutic range for warfarin patients

Anticoagulation (AC) clinics use the percentage of time in the therapeutic INR range (%TTR) to characterize the quality of management for patients treated with warfarin. In order to guide policy and procedure changes, the purpose of this quality improvement (QI) study was to characterize the AC patient population at The Johns Hopkins Hospital (JHH). We set out to investigate the impact of AC clinic provider continuity on the quality of anticoagulation management. This QI study is a retrospective chart review of 525 warfarin patients managed by pharmacists in the Hematology AC Management Clinic at JHH from June 28, 2013 to November 1, 2014. We recorded patient demographic and clinical characteristics and the quality of AC management using %TTR, and compared these parameters between patients with (Group A) and without a primary AC (Group B). Group A patients had a significantly higher %TTR than Group B patients (53.2 vs. 46.5 %, p = 0.008). In conclusion, we found that patients with a primary AC clinic provider had a higher %TTR than patients with multiple providers. If confirmed prospectively, this approach to warfarin management could represent one technique for AC clinics to optimize patient management and clinical outcomes.

Gastrointestinal Bleeding in Patients With Atrial Fibrillation Treated With Rivaroxaban or Warfarin: ROCKET AF Trial

BACKGROUND

Gastrointestinal (GI) bleeding is a common complication of oral anticoagulation.

OBJECTIVES

This study evaluated GI bleeding in patients who received at least 1 dose of the study drug in the on-treatment arm of the ROCKET AF (Rivaroxaban Once-daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation) trial.

METHODS

The primary outcome was adjudicated GI bleeding reported from first to last drug dose + 2 days. Multivariable modeling was performed with pre-specified candidate predictors.

RESULTS

Of 14,236 patients, 684 experienced GI bleeding during follow-up. These patients were older (median age 75 years vs. 73 years) and less often female. GI bleeding events occurred in the upper GI tract (48%), lower GI tract (23%), and rectum (29%) without differences between treatment arms. There was a significantly higher rate of major or nonmajor clinical GI bleeding in rivaroxaban- versus warfarin-treated patients (3.61 events/100 patient-years vs. 2.60 events/100 patient-years; hazard ratio: 1.42; 95% confidence interval: 1.22 to 1.66). Severe GI bleeding rates were similar between treatment arms (0.47 events/100 patient-years vs. 0.41 events/100 patient-years; p = 0.39; 0.01 events/100 patient-years vs. 0.04 events/100 patient-years; p = 0.15, respectively), and fatal GI bleeding events were rare (0.01 events/100 patient-years vs. 0.04 events/100 patient-years; 1 fatal events vs. 5 fatal events total). Independent clinical factors most strongly associated with GI bleeding were baseline anemia, history of GI bleeding, and long-term aspirin use.

CONCLUSIONS

In the ROCKET AF trial, rivaroxaban increased GI bleeding compared with warfarin. The absolute fatality rate from GI bleeding was low and similar in both treatment arms. Our results further illustrate the need for minimizing modifiable risk factors for GI bleeding in patients on oral anticoagulation.

Effectiveness and safety of dabigatran versus acenocoumarol in 'real-world' patients with atrial fibrillation

Aims

Randomized trials showed non-inferior or superior results of the non-vitamin-K-antagonist oral anticoagulants (NOACs) compared with warfarin. The aim of this study was to assess the effectiveness and safety of dabigatran (direct thrombin inhibitor) vs. acenocoumarol (vitamin K antagonist) in patients with atrial fibrillation (AF) in daily clinical practice.

Methods and results

In this observational study, we evaluated all consecutive patients who started anticoagulation because of AF in our outpatient clinic from 2010 to 2013. Data were collected from electronic patient charts. Primary outcomes were stroke or systemic embolism and major bleeding. Propensity score matching was applied to address the non-randomized design. In total, 920 consecutive AF patients were enrolled (442 dabigatran, 478 acenocoumarol), of which 2 × 383 were available for analysis after propensity score matching. Mean follow-up duration was 1.5 ± 0.56 year. The mean calculated stroke risk according to the CHA₂DS₂-VASc score was 3.5%/year in dabigatran vs. 3.7%/year acenocoumarol-treated patients. The actual incidence rate of stroke or systemic embolism was 0.8%/year [95% confidence interval (CI): 0.2–2.1] vs. 1.0%/year (95% CI: 0.4–2.1), respectively. Multivariable analysis confirmed this lower but non-significant risk in dabigatran vs. acenocoumarol after adjustment for the CHA₂DS₂-VASc score [hazard ratio (HR)_dabigatran = 0.72, 95% CI: 0.20–2.63, P = 0.61]. According to the HAS-BLED score, the mean calculated bleeding risk was 1.7%/year in both groups. Actual incidence rate of major bleeding was 2.1%/year (95% CI: 1.0–3.8) in the dabigatran vs. 4.3%/year (95% CI: 2.9–6.2) in acenocoumarol. This over 50% reduction remained significant after adjustment for the HAS-BLED score (HR_dabigatran = 0.45, 95% CI: 0.22–0.93, P = 0.031).

Conclusion

In ‘real-world’ patients with AF, dabigatran appears to be as effective, but significantly safer than acenocoumarol.

Engaging with quality improvement in anticoagulation management

Anticoagulants are highly effective at preventing thrombosis across a variety of clinical indications. However, their use can also lead to devastating effects, including major bleeding and death. Anticoagulation providers strive to balance the benefits of anticoagulant therapy with the risks of major bleeding. A measure of quality care can be used to assess the strengths and potential weaknesses in any system of coordinated care delivery. Quality measures in anticoagulation include patient-centered outcomes (e.g. major bleeding, time in the therapeutic range) and provider- or process-focused outcomes (e.g. compliance with guideline recommendations and response times to out-of-range laboratory values). Engaging in quality improvement activities allows anticoagulation providers to assess their own performance and identify areas for targeted interventions. This review summarizes the justification for engaging in quality improvement for anticoagulation management and describes a number of example programs. Interventions benefiting the management of both warfarin and the direct oral anticoagulants are included. The review also details potential quality measures and resources for any anticoagulation provider looking to begin a quality improvement process.

Independent predictors of poor vitamin K antagonist control in venous thromboembolism patients. Data from the EINSTEIN-DVT and PE studies

Vitamin K antagonists (VKA) are used to prevent recurrent disease in patients with venous thromboembolism (VTE). Their efficacy and safety depend on individual time in therapeutic range (iTTR) and variability of International Normalised Ratios (INR). We aimed to identify independent predictors of poor VKA control > 28 days. In a prospective cohort of 3825 VTE patients, separate logistic regression analyses were performed to identify predictors of low iTTR (first quartile) and instability (iTTR <median and variability >median). Subsequently, the association between these predictors and clinical outcomes was investigated. Weight < 50 kg (odds ratio [OR]=1.89; 95 % confidence interval [CI] 1.03-3.49), active cancer at baseline (OR=1.52; CI1.05-2.19), secondary VTE (OR=1.42; CI1.20-1.68), and INR < 2.0 at stop of double therapy (OR=1.35; CI1.09-1.67) were independent predictors of low iTTR. The first two were also predictive for instability (OR=1.96; CI1.06-3.63 and OR=1.95; CI1.36-2.80, respectively). ORs of early (≤ 28 days) low iTTR and instability depended on VKA type. In acenocoumarol users, early low iTTR was an independent predictor of subsequent low iTTR (OR=1.92; CI1.31-2.80) and instability (OR=1.55; CI1.07-2.23). In warfarin users, early low iTTR (OR=1.36; CI1.09-1.69) and instability (OR=1.25; CI1.01-1.55) were additionally predictive for low iTTR, but only the latter was predictive for instability (OR=1.91; CI1.57-2.32). Many predictors of VKA control also predicted premature discontinuation, but only region was prognostic for clinical outcome. In conclusion, we identified several independent predictors of low iTTR and instability > 28 days, which showed some similarities but did not fully overlap. Early VKA control was of additional value for prediction of both, but had to be interpreted in the context of VKA type.

International Normalized Ratio Variability: A Measure of Anticoagulation Quality or a Powerful Mortality Predictor

BACKGROUND

As atrial fibrillation (AF) carries twice the mortality hazard when compared with a similar population without diagnosed AF, the importance of risk stratifying is obvious. Several variables are related to outcome: age, comorbidities, and use of several medications, particularly oral anticoagulants. The CHA2DS2VASc score is an extremely useful tool to predict thromboembolic events and also mortality. The international normalized ratio (INR) variability is a treatment efficacy variable also associated with morbidity in patients receiving warfarin. The objective of the study is to compare the prognostic value of the CHA2DS2VASc versus the INR variability or its combination to predict mortality.

METHODS

In this observational study, we analyzed 589 patients from our Atrial Fibrillation Cohort, all on warfarin for more than 1 year and had more than 5 INRs performed in the last 2 years. The CHA2DS2VASc, HAS-BLED, and SAMe-TT2R2 scores were calculated as well as the INR variability using the time-in-therapeutic-range (TTR), the percentage of INRs (%INRs) within range, and the standard deviation of the INRs (SDINRs). Kaplan-Meier survival curves were plotted via different cutoff points.

RESULTS

The mean TTR was 53 ± 23%; 34.6% of the patients had a TTR above 64%. The mean %INRs in range was 50.2 ± 20.2; 17.3% of the population had %INRs in range above 70%. The mean SDINRs was .84 ± .54, and 38.4% had SDINRs below .79. Of 598, 139 (22%) discontinued warfarin treatment. Death was responsible for almost 50% of treatment discontinuation. Of 598, 68 patients died during the study period (11.5 %); the most frequent causes of death were heart failure (30%), bleeding (17%), and ischemic stroke (15%). Patient survival had a correlation with TTR, %INRs in range, SDINRs, left ventricular ejection fraction, CHA2DS2VASc, and the combination of CHA2DS2VASc + SDINRs (cutoff >1 and >.79, respectively).

CONCLUSIONS

INR variability is an extremely useful tool to assess anticoagulation quality. Calculation of both CHA2DS2VASc and INR variability appears to be extremely useful to predict mortality in patients with AF receiving warfarin. The SDINRs emerges as a strong mortality predictor compared to the other INR variability indexes.

Comparison of two approaches of INR-follow-up and determinants of INR-stability

INTRODUCTION

Patients with atrial fibrillation (AF) and treated with coumarins need a close follow-up of the international normalized ratio (INR)-values. This can be done by the general practitioner (GP) or by a haematologist in an outpatient hospital clinic.

OBJECTIVE

To compare both ways of follow-up and to investigate determinants of stable INR-patterns.

METHODS

Cross-sectional single-centre study in patients with AF treated at the UZ Brussel, a university hospital in Brussels. Of the 113 patients included in the study, 71 had their INR followed-up by their GP and 42 similar patients were followed-up by a haematologist. Data of these 113 patients were further analysed to identify possible determinants for stable INR-values.

RESULTS

The time in therapeutic range (TTR) did not significantly differ between both groups. However, patients in the GP-group had significantly more INR-values under 2.0 compared to patients from the haematologist-group (P =  0.044), whereas patients in the haematologist-group had significantly more INR-values above 3.0 compared to patients from the GP-group (P = 0.038). Reimbursement costs of both ways of follow-up were comparable, but the out-of-pocket costs for the patient were lower in the GP-group. The time since AF diagnosis was the only significant determinant predicting a higher TTR.

CONCLUSION

Both approaches of follow-up seem to lead to the same TTR, yielding no reason to advocate one approach above the other. However, the patient costs were lower when followed-up by the GP.

Self-management of warfarin therapy

BACKGROUND

Clinical studies from other countries show that self-management of warfarin therapy may reduce the risk of mortality, thromboembolism and complications when compared to conventional therapy. The purpose of this study was to train patients in self-management and compare the results with conventional therapy in Norway.

METHOD

A total of 23 patients who had previously been given conventional therapy by their GPs were instructed in how to measure INR (using the CoaguChek XS device) and administer warfarin dosage through a structured training programme over the course of 27 weeks. The participants continued with self-management for a further 28 weeks after the end of the training period. The time in the therapeutic range (TTR, measured as a percentage) was calculated and the TTR for conventional therapy and self-management were compared.

RESULTS

No significant difference in average TTR was found when comparing conventional therapy (70% (95% confidence interval (CI) 62-78)) with the self-management period (75% (95% CI 69-81, p = 0.24)). The percentage of extreme INR values (< 1.5 or > 5.0) was higher during conventional therapy than during self-management (6.8% vs. 1.0%, p < 0.001).

INTERPRETATION

No significant difference in TTR was found when comparing self-management and conventional warfarin therapy in our study, but for self-management there was a lower percentage of extreme INR values compared to conventional warfarin therapy.

Oral anticoagulant therapy and bleeding events with vitamin K antagonists in patients with atrial fibrillation in a Hungarian county hospital

Background

Vitamin K antagonists, despite their tight therapeutic spectrum and the fear of bleeding complications, were long the most important drugs used in anticoagulant therapy. The aim of this study was to evaluate the quality of anticoagulant therapy and its relation with bleedings in everyday clinical practice.

Material/Methods

We analyzed the data of 272 patients with non-valvular atrial fibrillation treated in our county hospital using retrospective data collection of the last 1008±384 days. The INR (International Normalized Ratio) values and the time in therapeutic range (TTR) were analyzed. We asked patients about bleeding complications and searched the medical records.

Results

The TTR proved to be 64% and there was no statistically significant difference between that of 252 (92.7%) patients taking acenocoumarol and 20 (7.3%) on warfarin. Analyzing various factors leading to TTR under 70%, we found that none of them have a significant impact. Significantly more bleeding events occurred in the first 3 months after the initiation of anticoagulant therapy and in patients with TTR under 70%, but the latter was not significant after adjustment for factors influencing bleeding (OR 1.607, CI 0.571–4.522, p=0.392).

Conclusions

Although the present study’s TTR values were similar to those found in the warfarin branch of various large-scale international trials and in real-life settings, further improvement of vitamin K antagonist therapy are necessary. As the possibilities for this are limited, we believe that the new type anticoagulant agents have a place in everyday clinical practice.

Computerized clinical decision support improves warfarin management and decreases recurrent venous thromboembolism

BACKGROUND

An explicit approach to warfarin dose adjustment using computerized clinical decision support (CDS) improves warfarin management. We report metrics of quality for warfarin management before and after implementation of CDS in a large health care system.

METHODS

A total of 2591 chronically anticoagulated patients were eligible for inclusion. We compared interpatient time in therapeutic range (TTR) and international normalized ratio (INR) variability before and after implementation of CDS. We report outcomes of major bleeding, thrombosis, and health care utilization.

RESULTS

Implementation of CDS significantly improved TTR (from 63.99% to 65.13%; P = .04) and reduced out-of-range INRs (from 42.39% to 39.97%; P < .001). Venous thromboembolism (relative risk [RR] 0.41; P < .001) emergency department utilization (RR 0.62; P < .001), and hospitalization (RR 0.62; P < .001) were reduced after CDS implementation. Major hemorrhage was more frequent after CDS implementation (RR 1.42; P = .01).

CONCLUSION

The CDS warfarin management was associated with improved TTR and decreased INR variability in a large cohort of chronically anticoagulated patients. Clinically relevant outcomes were broadly improved, although more bleeding events were observed.