Bleeding risk factors in chronic oral anticoagulation with acenocoumarol

Bleeding and asymptomatic overdose in patients under Vitamin K antagonist therapy: Frequency and risk factors

Background

Vitamin K antagonists are widely used in the treatment and prevention of thromboembolic disease. However, these drugs can cause serious side effects, especially bleeding. This study aims to evaluate frequency and risk factors of both bleeding and asymptomatic overdose in North African patients undergoing Vitamin K antagonist therapy.

Methods

We performed a cross-sectional study in patients undergoing Vitamin K antagonist therapy. A statistical analysis has been conducted to identify overdose and bleeding risk factors by using chi-square test (p < .05).

Results

One hundred and eleven patients were included. We recorded 14 cases of bleeding and 26 cases of asymptomatic overdose. Advanced age, poor adherence, concomitant use of paracetamol and history of previous bleeding are significant risk factors of over-anticoagulation. An INR value over 6 at admission, a high therapeutic target range for INR, concomitant use of acetylsalicylic acid, lack of information on overdose signs and measures to be taken in case of bleeding were identified as risk factors for bleeding.

Conclusion

Most of the risk factors identified in our study seem to be related to patients lack of information and education. These results highlight the importance of creating a therapeutic patient education program.

Polypharmacy is associated with an increased risk of bleeding in elderly patients with venous thromboembolism

BACKGROUND

Polypharmacy, defined as the concomitant use of multiple medications, is very common in the elderly and may trigger drug-drug interactions and increase the risk of falls in patients receiving vitamin K antagonists.

OBJECTIVE

To examine whether polypharmacy increases the risk of bleeding in elderly patients who receive vitamin K antagonists for acute venous thromboembolism (VTE).

DESIGN

We used a prospective cohort study.

PARTICIPANTS

In a multicenter Swiss cohort, we studied 830 patients aged ≥ 65 years with VTE.

MAIN MEASURES

We defined polypharmacy as the prescription of more than four different drugs. We assessed the association between polypharmacy and the time to a first major and clinically relevant non-major bleeding, accounting for the competing risk of death. We adjusted for known bleeding risk factors (age, gender, pulmonary embolism, active cancer, arterial hypertension, cardiac disease, cerebrovascular disease, chronic liver and renal disease, diabetes mellitus, history of major bleeding, recent surgery, anemia, thrombocytopenia) and periods of vitamin K antagonist treatment as a time-varying covariate.

KEY RESULTS

Overall, 413 (49.8 %) patients had polypharmacy. The mean follow-up duration was 17.8 months. Patients with polypharmacy had a significantly higher incidence of major (9.0 vs. 4.1 events/100 patient-years; incidence rate ratio [IRR] 2.18, 95 % confidence interval [CI] 1.32-3.68) and clinically relevant non-major bleeding (14.8 vs. 8.0 events/100 patient-years; IRR 1.85, 95 % CI 1.27-2.71) than patients without polypharmacy. After adjustment, polypharmacy was significantly associated with major (sub-hazard ratio [SHR] 1.83, 95 % CI 1.03-3.25) and clinically relevant non-major bleeding (SHR 1.60, 95 % CI 1.06-2.42).

CONCLUSIONS

Polypharmacy is associated with an increased risk of both major and clinically relevant non-major bleeding in elderly patients receiving vitamin K antagonists for VTE.

Surgical management of severe spontaneous hemorrhage of the abdominal wall complicating acenocoumarol treatment

Acenocoumarol is a vitamin K antagonist that is used for the treatment of acquired and congenital, both arterial and venous, thrombotic diseases. Its use is complicated by the narrow therapeutic range. Bleeding following oral anticoagulation, despite rare, remains the major complication. Most cases of hemorrhagic episodes usually require short hospitalization and transfusion, while surgical drainage of the hematoma is not recommended. However, in cases that conservative treatment isn't successful, surgical intervention remains an option. We present a case of severe spontaneous bleeding of the rectus abdominis muscle which was successfully managed surgically.

Factors affecting adherence to guidelines for antithrombotic therapy in elderly patients with atrial fibrillation admitted to internal medicine wards

INTRODUCTION

Current guidelines for ischemic stroke prevention in atrial fibrillation or flutter (AFF) recommend Vitamin K antagonists (VKAs) for patients at high-intermediate risk and aspirin for those at intermediate-low risk. The cost-effectiveness of these treatments was demonstrated also in elderly patients. However, there are several reports that emphasize the underuse of pharmacological prophylaxis of cardio-embolism in patients with AFF in different health care settings.

AIMS

To evaluate the adherence to current guidelines on cardio-embolic prophylaxis in elderly (> 65 years old) patients admitted with an established diagnosis of AFF to the Italian internal medicine wards participating in REPOSI registry, a project on polypathologies/polytherapies stemming from the collaboration between the Italian Society of Internal Medicine and the Mario Negri Institute of Pharmacological Research; to investigate whether or not hospitalization had an impact on guidelines adherence; to test the role of possible modifiers of VKAs prescription.

METHODS

We retrospectively analyzed registry data collected from January to December 2008 and assessed the prevalence of patients with AFF at admission and the prevalence of risk factors for cardio-embolism. After stratifying the patients according to their CHADS(2) score the percentage of appropriateness of antithrombotic therapy prescription was evaluated both at admission and at discharge. Univariable and multivariable logistic regression models were employed to verify whether or not socio-demographic (age >80years, living alone) and clinical features (previous or recent bleeding, cranio-facial trauma, cancer, dementia) modified the frequency and modalities of antithrombotic drugs prescription at admission and discharge.

RESULTS

Among the 1332 REPOSI patients, 247 were admitted with AFF. At admission, CHADS(2) score was ≥ 2 in 68.4% of patients, at discharge in 75.9%. Among patients with AFF 26.5% at admission and 32.8% at discharge were not on any antithrombotic therapy, and 43.7% at admission and 40.9% at discharge were not taking an appropriate therapy according to the CHADS(2) score. The higher the level of cardio-embolic risk the higher was the percentage of antiplatelet- but not of VKAs-treated patients. At admission or at discharge, both at univariable and at multivariable logistic regression, only an age >80 years and a diagnosis of cancer, previous or active, had a statistically significant negative effect on VKAs prescription. Moreover, only a positive history of bleeding events (past or present) was independently associated to no VKA prescription at discharge in patients who were on VKA therapy at admission. If heparin was considered as an appropriate therapy for patients with indication for VKAs, the percentage of patients admitted or discharged on appropriate therapy became respectively 43.7% and 53.4%.

CONCLUSION

Among elderly patients admitted with a diagnosis of AFF to internal medicine wards, an appropriate antithrombotic prophylaxis was taken by less than 50%, with an underuse of VKAs prescription independently of the level of cardio-embolic risk. Hospitalization did not improve the adherence to guidelines.

Patients with coronary, cerebrovascular or peripheral arterial obstructive disease differ in risk for new vascular events and mortality: the SMART study

AIMS

Atherosclerosis causes coronary artery disease (CAD), cerebrovascular disease (CVD) or peripheral arterial obstructive disease (PAOD). The risk of new vascular events and mortality is high. Direct comparisons of vascular event rates are scarce.

METHODS AND RESULTS

Vascular risk factors and outcome events of 3563 patients from a university hospital presenting with nondisabling CAD, CVD or PAOD were compared with regression analyses, adjusted for age and sex (median follow-up, 3.9 years). The primary outcome was the composite of myocardial infarction, stroke and vascular death. The risk among the three groups of outcomes was compared using the Cox regression analysis. At baseline, CAD patients were the most obese; PAOD patients smoked the most and suffered more often from hypertension and hyperlipidaemia. The average rate of vascular events was 2.5% per year; the hazard ratio (HR) of CVD/CAD was 1.7 [95% confidence interval (CI): 1.3-2.2] and PAOD/CAD was 1.8 (95% CI: 1.5-2.0). PAOD patients had a higher risk for coronary events than CAD (HR: 1.6; 95% CI: 1.2-2.1). Patients with CVD or PAOD had a higher risk for major bleeding than CAD patients (HR: 2.1; 95% CI: 1.4-3.2).

CONCLUSION

Patients with a recent CVD or PAOD have almost twice the risk for future vascular events than those with CAD.

Anticoagulation intensity and outcomes among patients prescribed oral anticoagulant therapy: a systematic review and meta-analysis

BACKGROUND

Patients taking oral anticoagulant therapy balance the risks of hemorrhage and thromboembolism. We sought to determine the association between anticoagulation intensity and the risk of hemorrhagic and thromboembolic events. We also sought to determine how under-or overanticoagulation would influence patient outcomes.

METHODS

We reviewed the MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and CINAHL databases to identify studies involving patients taking anticoagulants that reported person-years of observation and the number of hemorrhages or thromboemboli in 3 or more discrete ranges of international normalized ratios. We estimated the overall relative and absolute risks of events specific to anticoagulation intensity.

RESULTS

We included 19 studies. The risk of hemorrhage increased significantly at high international normalized ratios. Compared with the therapeutic ratio of 2-3, the relative risk (RR) of hemorrhage (and 95% confidence intervals [CIs]) were 2.7 (1.8-3.9; p < 0.01) at a ratio of 3-5 and 21.8 (12.1-39.4; p < 0.01) at a ratio greater than 5. The risk of thromboemboli increased significantly at ratios less than 2, with a relative risk of 3.5 (95% CI 2.8-4.4; p < 0.01). The risk of hemorrhagic or thromboembolic events was lower at ratios of 3-5 (RR 1.8, 95% CI 1.2-2.6) than at ratios of less than 2 (RR 2.4, 95% CI 1.9-3.1; p = 0.10). We found that a ratio of 2-3 had the lowest absolute risk (AR) of events (AR 4.3%/yr, 95% CI 3.0%-6.3%).

CONCLUSIONS

The risks of hemorrhage and thromboemboli are minimized at international normalized ratios of 2-3. Ratios that are moderately higher than this therapeutic range appear safe and more effective than subtherapeutic ratios.

Risk factors for bleeding during anticoagulation of atrial fibrillation in older and younger patients in clinical practice

BACKGROUND

The prevalence of atrial fibrillation increases with age, affecting approximately 5% of people aged >65 years and almost 10% of people aged >80 years.

OBJECTIVE

The goal of this study was to identify risk factors for bleeding during warfarin treatment of nonvalvular atrial fibrillation (NNVAF) in older patients (those aged >or=75 years) compared with younger patients (those aged <75 years) in clinical practice.

METHODS

All patients with NVAF newly started on warfarin at an anticoagulation clinic in a large university hospital were included in this prospective observational study. Patient details were recorded at their first visit; details of any bleeding events were recorded via telephone interview every 4 to 6 weeks for a minimum of 10 months. Patients were divided into 2 groups (ie, those >or=75 years old and those <75 years old). Logistic regression analysis was used to identify risk factors for bleeding.

RESULTS

A total of 402 patients were included in the study. Group I comprised 203 patients <75 years old (mean [SD] age, 64.33 [8.33] years) and group II comprised 199 patients >or=75 years old (mean [SD] age, 80.44 [3.99] years). Follow-up ranged from 1 to 31 months (mean [SD], 19 [8.11] months). For major bleeding, number of medications was a significant risk factor in older patients (odds ratio [OR], 3.0; 95% CI, 1.2-7.8 [P = 0.02 ]) and range of the international normalized ratio (INR) was a significant risk factor in both groups. For every unit increase in the range of INR, the odds of major bleeding increased by 0.6 (OR, 1.6; 95% CI, 1.2-2.4 [P = 0.03 ]) in younger patients and by 0.4 (OR, 1.4; 95% CI, 1.07-1.99 [P = 0.04 ])in older patients. For minor bleeding, history of hypertension was the only significant risk factor in older patients (OR, 3.3; 95% CI, 1.3-8.1 [P = 0.01 ]), while history of ischemic heart disease was the only risk factor in younger patients (OR, 1.9; 95% CI, 1.1-5.4 [P = 0.04 ]).

CONCLUSIONS

Bleeding pattern was similar in both age groups regarding severity, onset, anatomic site of bleeding, and INR values during the bleeding event. Risk factors for episodes of major bleeding, which are more of a clinical concern, are potentially modifiable. They include quality of anticoagulation control in both groups and number of medications in the older age group.

Effect of setting, monitoring intensity and patient experience on anticoagulation control: a systematic review and meta-analysis of the literature

OBJECTIVES

To investigate the relationship between time spent in the recommended target International Normalised Ratio (INR) range and the setting and intensity of anti coagulant monitoring, in both treatment-experienced and treatment-naive atrial fibrillation (AF) patients receiving oral anticoagulation (OAC) therapy for the prevention of ischaemic stroke.

RESEARCH DESIGN AND METHODS

Systematic review of published studies on participants with atrial fibrillation on anticoagulation therapy. We compared frequent monitoring (well-controlled, according to a strict protocol) versus infrequent monitoring (frequency representative of routine clinical practice), specialised care versus usual care, and naive versus prior anticoagulant use. Meta-analysis was performed using a random effects model.

RESULTS

36 studies were included, 22 (primary data) of AF patients managed in line with the consensus guidelines target INR range of 2.0-3.0, and 14 studies (secondary data) of mixed patient groups, including AF, with an INR target of 2.0-3.5. Both data sets were combined for sensitivity analysis. Pooled mean time in INR range was 59.1% (95% CI: 55.5, 62.8%) and 64.3% (95% CI: 60.5, 68.0%) for infrequent monitoring and frequent monitoring, respectively. Significantly more time was spent in range in specialist care settings compared to usual care: +11.3% (95% CI: 0.1-21.7%). Naive OAC users spent less time in range 56.5% (95% CI: 45.5-67.5%) than existing users 61.2% (95% CI: 57.2-65.2%). All of these differences were found to be significant in the sensitivity analyses.

CONCLUSIONS

INR control is variable and dependent on monitoring intensity and duration of anticoagulant therapy.

Frequency of adverse events in patients with poor anticoagulation: a meta-analysis

BACKGROUND

Patients taking anticoagulants orally over the long term have international normalized ratios (INRs) outside the individual therapeutic range more than one-third of the time. Improved anticoagulation control will reduce hemorrhagic and thromboembolic event rates. To gauge the potential effect of improved anticoagulation control, we undertook to determine the proportion of anticoagulant-associated events that occur when INRs are outside the therapeutic range.

METHODS

We conducted a meta-analysis of all studies that assigned hemorrhagic and thromboembolic events in patients taking anticoagulants to discrete INR ranges. We identified studies using the MEDLINE (1966-2006) and EMBASE (1980-2006) databases. We included studies reported in English if the majority of patients taking oral anticoagulants had an INR range with a lower limit between 1.8 and 2 and an upper limit between 3 and 3.5, and their INR at the time of the hemorrhagic or thromboembolic event was recorded.

RESULTS

The final analysis included results from 45 studies (23 that reported both hemorrhages and thromboemboli; 14 that reported hemorrhages only; and 8, thromboemboli only) involving a median of 208 patients (limits of interquartile range [25th-75th percentile] 131-523 subjects; total n = 71 065). Of these studies, 64% were conducted at community practices; the remainder, at anticoagulation clinics. About 69% of the studies were classed as having moderate or high quality. Overall, 44% (95% confidence interval [CI] 39%-49%) of hemorrhages occurred when INRs were above the therapeutic range, and 48% (95% CI 41%-55%) of thromboemboli took place when below it. The mean proportion of events that occurred while the patient's INR was outside the therapeutic range was greater for studies with a short mean follow-up (< 1 yr). Between-study heterogeneity was significant (p < 0.001).

INTERPRETATION

Improved anticoagulation control could decrease the likelihood of almost half of all anticoagulant-associated adverse events.

Anticoagulation control in the peri-hospitalization period

Oral anticoagulants (OAC) are effective and safe if the international normalized ratio (INR) is maintained within a narrow therapeutic range. Hospitalization is independently associated with poor anticoagulation control. The objective of this study is to describe how anticoagulation control changes in the peri-hospitalization period. This study is a retrospective cohort study using population-based administrative databases. INR results were retrieved from a population-based laboratory database. INR levels between laboratory measures were estimated using linear interpolation. Auto-regressive, integrated, moving average (ARIMA) time-series modeling was used to determine how anticoagulation control changed in the peri-hospitalization period. The study included 5,380 elderly patients in Eastern Ontario between 1 September 1999 and 1 September 2000 taking OACs. Results showed that 951 (17.7%) were hospitalized during their OAC therapy [thrombotic, n = 52 (1.0%); hemorrhagic, n = 140 (2.6%); other hospitalization types, n = 759 (14.1%)]. All measures of anticoagulation control changed significantly in the peri-hospitalization period. Before hemorrhagic admissions, mean INR and proportion with INR > 5 increased significantly (daily increase 0.024, P = .03 and 0.2%, P = .01). Following other hospitalization types, the proportion of patients with INR < 1.5 was significantly increased (daily increase 0.19%, P = .02). Patients admitted to the hospital for a variety of indications have significantly worse anticoagulation control in the peri-hospitalization period. Anticoagulated patients discharged after medical hospitalizations could be targeted for improved anticoagulation control.

Burden of Potentially Avoidable Anticoagulant-Associated Hemorrhagic and Thromobembolic Events in the Elderly

BACKGROUND

On average, patients receiving therapy with oral anticoagulants (OACs) in the community are in the therapeutic range only 55% of the time. Anticoagulation control strongly influences the risk of hemorrhagic and thromboembolic events in such patients. However, not all anticoagulation-associated events are attributable to poor anticoagulation control, nor do all hemorrhagic or thromboembolic events occur in anticoagulated patients.

OBJECTIVE

Measure the proportion of serious hemorrhagic and thromboembolic events that would be avoided if anticoagulation control was perfect.

METHODS

A retrospective cohort study of eastern Ontario using population-based administrative databases. Anticoagulation control was determined for each day of OAC exposure using linear interpolation. Incident hemorrhagic or thromboembolic hospitalizations for control and OAC patients were identified. Hemorrhages and thromboemboli in OAC patients were deemed to be avoidable if they occurred at international normalized ratios of > 3 and < 2, respectively.

RESULTS

The study included > 183,000 patient-years of observation with 6,400 patient-years of OAC exposure. Anticoagulation control could be determined for 51.5% of OAC exposure time. Control patients had hemorrhagic and thromboembolic event rates of 1.8% and 1.5% per year, respectively. A total of 10,020 people were exposed to OACs, and spent 14.2% and 26.7% of the time, respectively, with excessively high and low anticoagulation intensity. Excessively high anticoagulation intensity explained 25.6% (95% confidence interval [CI], 19.4 to 31.7) and 2.0% (95% CI, 1.5 to 2.5) , respectively, of all serious hemorrhages in the anticoagulated and entire population. Excessively low anticoagulation intensity explained 11.1% (95% CI, 4.4 to 17.7) and 1.1% (95% CI, 0.7 to 1.6) of all thromboemboli, respectively.

CONCLUSIONS

Our study showed that extreme anticoagulation intensity significantly impacted the health of the population. Improving anticoagulation control will have significant effects on the incidence of serious hemorrhagic and thromboembolic events in the both the anticoagulated and entire populations.

Oral anticoagulant treatment: risk factors involved in 500 intracranial hemorrhages

Intracranial bleeding is the most severe complication caused by anticoagulant or antiplatelet treatment. The increasing use of this therapy, especially in older people, makes the balance between clinical benefit and bleeding risk an important consideration. A retrospective study of all consecutive 500 intracranial hemorrhages in the West Valladolid area, approximately 220,000 people, during the period 1998 to 2004, was performed. In relation to mortality, predisposing conditions were included, such as age, antithrombotic treatment, arterial hypertension, cancer, blood diseases, vascular malformations, and traumatisms. The incidence of intracranial hemorrhage was 310 per 100,000 per year with a mortality of 30%. Higher mortality was found in antiplatelet-treated patients (44.9%) than in anticoagulated patients (31.1%). This may be related to a different mean age of 78 vs. 71 years. Arterial hypertension was the most frequent risk factor (45.1% in nontreated patients, 60% anticoagulated, and 75.5% antiplatelet). The relative risk of intracranial bleeding in anticoagulated patients was 11.2 (p < 0.001) with an incidence of 0.03% and a median of 14 months since treatment began. The median INR was 3.3. In 40% of the patients the previous five controls were in range. Strict consideration of indications criteria joined to a better control of risk factors may avoid intracranial bleeding episodes.

Effect of Study Setting on Anticoagulation Control

BACKGROUND

For patients receiving therapy with oral anticoagulants (OACs), the proportion of time spent in the therapeutic range (ie, anticoagulation control) is strongly associated with bleeding and thromboembolic risk. The effect of study-level factors, especially study setting, on anticoagulation control is unknown.

OBJECTIVES

Describe anticoagulation control achieved in the published literature. We also used metaregressive techniques to determine which study-level factors significantly influenced anticoagulation control.

STUDIES

All published randomized or cohort studies that measured international normalized ratios (INRs) serially in anticoagulated patients and reported the proportion of time between INRs ranging from 1.8 to 2.0 and 3.0 to 3.5.

RESULTS

We identified 67 studies with 123 patient groups having 50,208 patients followed for a total of 57,154.7 patient-years. A total of 68.3% of groups were from anticoagulation clinics, 7.3% were from clinical trials, and 24.4% were from community practices. Overall, patients were therapeutic 63.6% of time (95% confidence interval [CI], 61.6 to 65.6). In the metaregression model, study setting had the greatest effect on anticoagulation control with studies in community practices having significantly lower control than either anticoagulation clinics or clinical trials (-12.2%; 95% CI, -19.5 to -4.8; p < 0.0001). Self-management was associated with a significant improvement of time spent in the therapeutic range (+7.0%; 95% CI, 0.7 to 13.3; p = 0.03).

CONCLUSIONS

Patients who have received anticoagulation therapy spend a significant proportion of their time with an INR out of the therapeutic range. Patients from community practices showed significantly worse anticoagulation control than those from anticoagulation clinics or clinical trials. This should be considered when interpreting the results of, and generalizing from, studies involving OACs.

Patients' perceptions regarding oral anticoagulation therapy and its effect on quality of life

OBJECTIVE

Anticoagulation clinics have improved the time spent within therapeutic range and decreased hemorrhagic complications and costs in chronic oral anticoagulation. Whether these benefits correlate to patients' quality of life (QOL) remains to be determined. The impact of patients' perceptions about anticoagulation on QOL has not been evaluated. The objective of this study was to evaluate prospectively patients' perceptions and quality of life in patients chronically anticoagulated.

RESEARCH DESIGN AND METHODS

A cross-sectional study was designed to investigate the prevalence of positive and negative perceptions about oral anticoagulation therapy (OAT) and to identify vulnerable groups. Patients anonymously completed the SF-36 survey and a questionnaire that focused on patients' perceptions of protection from thrombotic complications or fear of haemorrhage due to the anticoagulation. We related those perceptions to the General Health SF-36 score, to the patient's characteristics, the absolute bleeding risk (i.e. intended International Normalized Ratio [INR]), duration of therapy and medical attention.

RESULTS

One thousand patients were included and 905 questionnaires evaluated. Most patients felt protected and better since the beginning of therapy (71.5% and 61.5%, respectively). Patient characteristics associated with negative perceptions were; female sex (Odds Ratio [OR] 1.58, 95% Confidence Interval [CI] 1.06-2.36, p = 0.01); patients with less than 1 year of therapy (OR 2.16, 95% CI 1.34-3.48, p = 0.006); those not satisfied with medical attention (OR 2.86, 95% CI 1.53-5.18, p = 0.0001); and those that modified their lifestyle (OR 2.75, 95% CI 1.49-4.91, p = 0.0002). Patients with a lower bleeding risk (INR 2.0-3.0) had more negative perceptions than those with a higher risk. Patients with negative perceptions achieved the lowest score in the SF-36 survey. Haemorrhages did not affect patients' perception or QOL.

CONCLUSIONS

Patients' perceptions correlated with QOL. We were able to identify patient characteristics associated with poor QOL and thus the group of patients whose negative perceptions most warranted special attention from their clinicians.

Evaluación del programa piloto de descentralización del control del tratamiento anticoagulante oral en el Servicio Navarro de Salud-Osasunbidea

BACKGROUND AND OBJECTIVE

The objective of this study was the evaluation of the pilot programme of decentralization of oral anticoagulant therapy (OAT) in eight basic health zones (ZBS) for the first six months and then a year after the programme was put into practice.

PATIENTS AND METHOD

Descriptive transversal study. It includes all patients aged 14 years or older in the OAT (540 in the initial period and then 640 more) in eight ZBS (five urban and three rural). The evaluation was done including: prevalence of INR in control (2-3 or 2.5-3.5, according to indications), clinically suitable INR (INR in control +/- 0.2) and INR in control +/- 0.5, accumulated thrombosis and bleeding incidence. Source data: ANTICOAGN computer programme.

RESULTS

Comparison of INR control between both periods: 59% against 63.9% of INR in the range of INR in control (p < 0.001), 72.8% against 78.8% for clinically suitable INR (p < 0.001), and 86.6% against 91.4% for INR in control +/- 0.5 (p < 0.001). Accumulated incidence of bleeding episodes in 6 months: Pilot: 1.1% (0.7% majors and 0.4% minors). Subsequent period: 3.6% (0.6% majors and 3% minors).

CONCLUSIONS

The decentralization of control of the OAT with adequate resources implies a greater accessibility for the patient. The control of INR is acceptable and has improved significantly over the second period. We have detected an improvement in the increase of the INR below that of the range of the control INR. The incidence of minor hemorrhages has increased, owing probably to a better recording.

Hemorrhagic Complications of Anticoagulant Treatment

This chapter about hemorrhagic complications of anticoagulant treatment is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Bleeding is the major complication of anticoagulant therapy. The criteria for defining the severity of bleeding varies considerably between studies, accounting in part for the variation in the rates of bleeding reported. The major determinants of vitamin K antagonist-induced bleeding are the intensity of the anticoagulant effect, underlying patient characteristics, and the length of therapy. There is good evidence that vitamin K antagonist therapy, targeted international normalized ratio (INR) of 2.5 (range, 2.0 to 3.0), is associated with a lower risk of bleeding than therapy targeted at an INR > 3.0. The risk of bleeding associated with IV unfractionated heparin (UFH) in patients with acute venous thromboembolism (VTE) is < 3% in recent trials. This bleeding risk may increase with increasing heparin dosages and age (> 70 years). Low molecular weight heparin (LMWH) is associated with less major bleeding compared with UFH in acute VTE. UFH and LMWH are not associated with an increase in major bleeding in ischemic coronary syndromes, but are associated with an increase in major bleeding in ischemic stroke. Information on bleeding associated with the newer generation of antithrombotic agents has begun to emerge. In terms of treatment decision making for anticoagulant therapy, bleeding risk cannot be considered alone, ie, the potential decrease in thromboembolism must be balanced against the potential increased bleeding risk.

The use of vitamin K in patients on anticoagulant therapy: a practical guide

Anticoagulation with antivitamin K (AVK) is very effective for primary and secondary prevention of thromboembolic events. However, questions persist about the risks and management of over-anticoagulation. For reversal of excessive anticoagulation by warfarin, AVK withdrawal, oral or parenteral vitamin K administration, prothrombin complex or fresh frozen plasma may be used, depending on the excess of anticoagulation, the existence and site of active bleeding, patient characteristics and the indication for AVK. In over-anticoagulated patients, vitamin K aims at rapid lowering of the international normalized ratio (INR) into a safe range to reduce the risk of major bleeding and therefore improving patient outcome without exposing the patient to the risk of thromboembolism due to overcorrection, resistance to AVK, or an allergic reaction to the medication. The risk of bleeding increases dramatically when the INR exceeds 4.0-6.0, although the absolute risk of bleeding remains fairly low, <5.5 per 1000 per day. Patient characteristics, including advanced age, treated hypertension, history of stroke, and concomitant use of various drugs, affect the risk of bleeding. The absolute risk of thromboembolism associated with overcorrection appears to be in the same range as the risk of bleeding due to over-anticoagulation. The use of vitamin K in patients with warfarin over-anticoagulation lowers excessively elevated INR faster than withholding warfarin alone; however, it has not been clearly demonstrated that vitamin K treatment does, in fact, lower the risk of major hemorrhage. As vitamin K administration via the intravenous route may be complicated by anaphylactoid reactions, and via the subcutaneous route by cutaneous reactions, oral administration is preferred. A dose of 1-2.5mg of oral phytomenadione (vitamin K(1)), reduces the range of INR from 5.0-9.0 to 2.0-5.0 within 24-48 hours, and for an INR >10.0, a dose of 5mg may be more appropriate. Overcorrection of the INR or resistance to warfarin is unlikely if the above doses of vitamin K are used. Vitamin K is less effective for over-anticoagulation after treatment with acenocoumarol or phenprocoumon than after treatment with warfarin.

Primary and secondary stroke prevention in nonrheumatic atrial fibrillation by oral anticoagulation

The risk of stroke or embolism in atrial fibrillation (AF) patients can be reduced by 68% by oral anticoagulation (OAC). This review is aimed to (1) summarize indications for OAC in patients with AF, (2) give an overview of the current knowledge of risk factors for bleeding complications of OAC and (3) give practical recommendations for an optimal OAC therapy in the neurological setting. Indications for OAC are increased age (>75 years), arterial hypertension, diabetes mellitus, previous thromboembolism, heart failure and, probably, coronary heart disease. Risk factors for bleeding complications are overanticoagulation with international normalized ratios (INRs) >3.0, increased age, arterial hypertension, diabetes mellitus, previous thromboembolism, polypharmacy, the early phase of OAC therapy and a lack of patients' education. Before initiation of OAC, the patient should be screened for potential bleeding sites. Careful monitoring of OAC comprises fixed appointments for the INR value determination, tracking for the patient, if he does not attend, advices about pain therapy, information about the influence of diet on the INR value and drug interaction, unscheduled INR determination in case of acute disorders and regular assessment if OAC is still indicated. Monitoring of OAC needs an effort, which has to be adequately estimated by the health care system.

Acenocoumarol therapy in pediatric patients

To determine guidelines for administering and monitoring acenocoumarol therapy in children, 93 patients (median 5.1 years, range: 0.2-18 years) were prospectively evaluated over a 33-month period. The loading doses used were: <1 year, 0.20 mg x kg-1; >1-5 years, 0.09 mg x kg-1; 6-10 years, 0.07 mg x kg-1; 11-18 years, 0.06 mg x kg-1. In this study, the loading dose and the dose to achieve and maintain target therapeutic range (TTR) for acenocoumarol are age-dependent, with infants having the highest and teenagers having the lowest requirements. The use of a different loading dose according to age has allowed most of the children (80%) in all the age groups to achieve TTR in less than 1 week. No patients had serious bleeding or thrombotic complications. We conclude that there is an age-dependent response to acenocoumarol in pediatric patients. The implementation of an age-adjusted loading dose regimen reduces the length of hospitalization required to achieve effective anticoagulant therapy.

Low rate of bleeding and thrombotic complications of oral anticoagulant therapy independent of age in the real-practice of an anticoagulation clinic

Over past years, there has been a world-wide increase in oral anticoagulant treatment (OAT). This study was aimed at evaluating the efficacy and safety of OAT managing in a real-practice situation. Nine hundred and three consecutive unselected patients referred for the control of OAT to the Anticoagulation Clinic of the University of Florence were studied. The total follow-up period was 1679 patient-years. The rate of total, major and fatal bleeding events was 5.0, 1.1 and 0.06 per 100 patient-years, respectively. In patients with a target International Normalized Ratio (INR) > or = 3, a significantly higher rate of bleeding (P = 0.02) with respect to patients with a target INR < 3 was observed. The rate of all thrombotic events was 3.8 per 100 patient-years. The rate of major and fatal thrombotic events were 2.4 and 0.4 per 100 patient-years, respectively. At INR >/= 4.5 the rate of bleeding was significantly higher (P = 0.005) than at lower INR. At INR < 2 the rate of all thrombotic events was significantly higher (P = 0.00001) with respect to more elevated intensities of anticoagulation. A low incidence of complications may be obtained even in elderly outpatients on OAT followed at an anticoagulation clinic.

[Identification of factors responsible for oral over-anticoagulation in outpatients with heart disease]

BACKGROUND

Few studies have attempted to investigate the clinical course or identify factors responsible for excessive anticoagulation in patients with heart disease.

OBJECTIVES

To determine the incidence of excessive anticoagulation in outpatients with heart disease treated with acenocoumarol, analyze the factors related with over-anticoagulation, and identify bleeding complications.

PATIENTS AND METHOD

This 7-month prospective observational study included consecutive outpatients anticoagulated with acenocoumarol. They were seen in an anticoagulation unit. The high INR group of 55 over-anticoagulated patients had at least one test with INR > 5. The control group of 49 patients had INR results strictly within therapeutic range.

RESULTS

A total of 3,683 INR determinations were made in 512 patients. Seventy-seven tests had an INR > 5 (a 2% overall incidence of high-INR). In the group of 55 INR < 5 patients, 31% had more than one INR determination > 5 during follow-up. Multivariate analysis identified four variables as independent predictors of over-anticoagulation: artificial heart valve, poor treatment compliance, addition of potentially interactive new drugs, and illness in the last month. The high-INR group patients had more bleeding episodes (21.8 vs 4.08%; p = 0.008), one of which was major.

CONCLUSION

The incidence of excessive oral anticoagulation in our outpatient population was similar to that reported in other studies. Patients with INR > 5 had more total bleeding complications, mostly minor. It is recommended to proceed carefully with oral anticoagulant therapy in patients with an artificial heart valve, suspected poor treatment compliance, addition of potentially interactive new drugs, and illness in the last month.

Complications of minor cutaneous surgery in patients under anticoagulant treatment

Anticoagulant use is common in the elderly population. The role of these medications in the postoperative period is not well defined. We designed a prospective study to evaluate the incidence of postoperative complications in patients taking aspirin and warfarin. A prospective study was performed on 102 patients undergoing minor cutaneous plastic surgery. The number of subjects using regular aspirin, warfarin, and that of the patients with no anticoagulant medication were 37, 21, and 44, respectively. Complications were defined as minor, moderate, or major based on predetermined criteria. Of patients taking warfarin, 57% had some complication, significantly more than complications in the control group. The number of major complications in the warfarin group was significantly higher than those of the control and aspirin groups (p = 0.02). Also, the total number of complications in the warfarin group was significantly higher than the control group, but there was no significant difference between aspirin and control groups (p > 0.05). Cutaneous surgery in patients who receive warfarin is associated with a risk of major complication, but this risk does not exist in the patients receiving chronic aspirin treatment.

Effect of low-dose aspirin on the international normalized ratio variability in patients with mechanical heart valve prostheses

An increased risk of bleeding is associated with a more intense oral anticoagulation, a greater international normalized ratio (INR) variability and the use of aspirin. We studied the INR variability of patients (n = 121) with modern heart valves who had been prospectively randomized to receive acenocoumarol at a targeted INR of 2.4-3.6 plus aspirin 100 mg/day or acenocoumarol alone at the same dosage, to evaluate whether aspirin influences variability and thus the risk of bleeding. Variability was similar in patients with no events regardless of the use of aspirin. A statistically significantly higher variability was observed in patients with bleeding events independently of the use of aspirin. Nevertheless, the concomitant use of aspirin in patients with a high variability should be monitored closely and thoroughly.

[Oral anti-coagulants in an urban health centre. The first years results]

OBJECTIVES

To assess the management of oral anti-coagulation treatment (OAT) by family doctors and nurses from a health centre (HC) during its first year.

DESIGN

Descriptive cross-sectional study.Setting. La Chana, an urban HC in Granada, covering 19,362 inhabitants in family care units.

PARTICIPANTS

220 patients with acenocumarol prescribed during the year 2000. The criterion for inclusion was to have at least 3 OAT check-ups a year. 24 people were excluded.Interventions. Recruitment by personal invitation at the clinic. Capillary blood analyses and dose adjustments by the 10 nurses and 10 family doctors of the HC. Internationally recognised therapeutic ranges.

MAIN MEASUREMENTS

Prevalence of OAT: prescriptions of acenocumarol. Recruitment: patients monitored at the HC.

INDICATIONS

those found in the clinical records. Monitoring: % of patients with INR within range in final annual check-up.

COMPLICATIONS

rate of haemorrhages, thrombo-embolic accidents and other secondary effects.

RESULTS

196 patients followed OAT, a prevalence of 10.12 per thousand, with 19.6 patients per family doctor. The HC monitored 122 (62.24%); and the hospital, 74 (37.76%). The HC carried out 1,224 check-ups, 208 in the homes of 21 patients. There were 70.5% within the therapeutic range. Only 13% were in a situation of dose adjustment. Most common indications: non-rheumatic auricular fibrillation 65, TVP/TEP 27, mechanical cardiac prostheses 22. There were no fatal haemorrhages. Major haemorrhages ran at 2.22% of patients a year; and minor ones, at 6.68%. There were no thrombo-embolic accidents. There were two skin allergies.

CONCLUSIONS

The study showed good results, in line with the findings of other studies.

Evaluation of risk factors for stroke/embolism and of complications due to anticoagulant therapy in atrial fibrillation

BACKGROUND AND PURPOSE

We sought to assess in outpatients with atrial fibrillation and oral anticoagulation (1) whether the complication rate is influenced by the presence of the risk factors age >65 years, arterial hypertension, diabetes, or previous stroke; (2) whether the complication rate is influenced by the number of additional drugs taken by patients; and (3) whether problems and interventions differ between patients with or without complications.

METHODS

- Clinical characteristics, drugs, problems, interventions, and complications were registered during 2 years.

RESULTS

- Three hundred sixty patients (mean age, 68 years; 43% female) were observed for 383 patient-years. Patients aged >65 years had more serious, life-threatening, or fatal complications (11% versus 5.3%/100 patient-years; P=0.0428) than younger patients. Patients with diabetes had more life-threatening and fatal complications (2.8% versus 0.6%/100 patient-years; P=0.0354) than patients without. The complication rate did not differ regarding the presence of previous stroke or hypertension. Patients who took </=3 drugs had fewer complications than patients who took more (4.3% versus 24.4%/100 patient-years; P=0.0041). Patients with complications complained more of chest (48% versus 28%/100 patient-years; P=0.0113) and abdominal pain (30% versus 13%/100 patient-years; P=0.0057), more frequently failed to keep appointments (134% versus 107%/100 patient-years; P=0.0321), had a higher tracking rate (134% versus 105%/100 patient-years; P=0.0272), and took more additional drugs (4.6 versus 3.5 drugs per day; P=0.0063) than patients with no complications.

CONCLUSIONS

- Patients with increased age or diabetes mellitus or those who take >3 drugs per day have an increased complication rate and thus need especially careful monitoring of oral anticoagulation, including adequate pain control.

Reversal of excessive oral anticoagulation with a low oral dose of vitamin K1 compared with acenocoumarine discontinuation. A prospective, randomized, open study

We performed a prospective, randomized, open study in 109 outpatients under chronic anticoagulation with acenocoumarine, presenting with International Normalized Ratios (INRs) > or = 6.0 and no or minor bleeding. All the patients withheld one dose of acenocoumarine; in addition, a treated group also received 1 mg oral vitamin K1. We aimed at a post-intervention INR < 6.0, with a target zone of 2.0-4.0. The INRs were lowered from a mean of 8.1 +/- 1.7 to 4.9 +/- 2.5 in the controls (P = 0.0000) and from 8.4 +/- 2.4 to 3.3 +/- 3 in the treated patients (P = 0.0000). There were no differences in the percentage of patients with post-intervention INRs < 6.0 or within the therapeutic zone. One-third of the treated patients and only 2% of the controls reached INRs < 2.0 (P = 0.0003). Oral vitamin K1 offered no advantage to the simple discontinuation of one dose of acenocoumarine. A substantial number of treated patients were consequently exposed to under-anticoagulation.