Use of oral anticoagulants in older patients

Impact of age on the efficacy and safety of extended-duration thromboprophylaxis in medical patients

The EXCLAIM study enrolled hospitalised acutely ill medical patients with age >40 years and recently-reduced mobility into a trial of extended-duration anticoagulant thromboprophylaxis. This post-hoc analysis evaluated the impact of age on patient outcomes. After completion of open-label therapy with enoxaparin 40 mg once-daily (10 ± 4 days), eligible patients underwent randomisation to receive double-blind therapy of enoxaparin (n=2,975) or placebo (n=2,988) for 28 ± 4 days. During follow-up, the venous thromboembolism (VTE) risk increased with age in both treatment groups. In patients with age >75 years, those who received extended-duration enoxaparin had lower incidence of VTE (2.5% vs 6.7%; absolute difference [AD] [95% confidence interval]: −4.2% [−6.5, −2.0]), proximal deep-vein thrombosis (2.5% vs 6.6%; AD −4.1 % [−6.2, −2.0]), and symptomatic VTE (0.3% vs 1.5%; AD −1.2% [−2.2, −0.3]), in comparison to those who received placebo. In patients with age ≤75 years, those who received enoxaparin had reduced VTE (2.4% vs 2.8%; AD −0.4% [−1.5, 0.7]) and symptomatic VTE (0.2% vs 0.7%; AD −0.6% [−1.0, −0.1]) in comparison to those who received placebo. In both age subgroups, patients who received enoxaparin had increased rates of major bleeding versus those who received placebo: age >75 years (0.6% vs 0.2%; AD +0.3% [−0.2, 0.9], respectively); age ≤75 years (0.7% vs 0.2%; AD +0.5% [0.1, 0.9]). Patients in both age subgroups that received enoxaparin had similar low bleeding rates (0.6% and 0.7%, respectively). VTE risk increased with age, though the bleeding risk did not. Patients with age >75 years had a more favourable benefit-to-harm profile than younger patients.

Recommendations to prescribe in complex older adults: results of the CRIteria to assess appropriate Medication use among Elderly complex patients (CRIME) project

The occurrence of several geriatric conditions may influence the efficacy and limit the use of drugs prescribed to treat chronic conditions. Functional and cognitive impairment, geriatric syndromes (i.e. falls or malnutrition) and limited life expectancy are common features of old age, which may limit the efficacy of pharmacological treatments and question the appropriateness of treatment. However, the assessment of these geriatric conditions is rarely incorporated into clinical trials and treatment guidelines. The CRIME (CRIteria to assess appropriate Medication use among Elderly complex patients) project is aimed at producing recommendations to guide pharmacologic prescription in older complex patients with a limited life expectancy, functional and cognitive impairment, and geriatric syndromes, and providing physicians with a tool to improve the quality of prescribing, independent of setting and nationality. To achieve these aims, we performed the following: (i) Existing disease-specific guidelines on pharmacological prescription for the treatment of diabetes, hypertension, congestive heart failure, atrial fibrillation and coronary heart disease were reviewed to assess whether they include specific indications for complex patients; (ii) a literature search was performed to identify relevant articles assessing the pharmacological treatment of complex patients; (iii) A total of 19 new recommendations were developed based on the results of the literature search and expert consensus. In conclusion, the new recommendations evaluate the appropriateness of pharmacological prescription in older complex patients, translating the recommendations of clinical guidelines to patients with a limited life expectancy, functional and cognitive impairment, and geriatric syndromes. These recommendations cannot represent substitutes for careful clinical consideration and deliberation by physicians; the recommendations are not meant to replace existing clinical guidelines, but they may be used to help physicians in the prescribing process.

VKORC1 and CYP2C9 Genotype Variations in Relation to Warfarin Dosing in Korean Stroke Patients

Background and Purpose

Variant alleles of CYP2C9 and VKORC1 account for differences in anticoagulation response. We sought to establish a warfarin dosing formula for individualized target International Normalization Ratio of Prothrombin Times (INRs) using data from single nucleotide polymorphisms (SNPs) in VKORC1 and CYP2C9 in Korean patients.

Methods

Ischemic stroke patients displaying stable target INR for at least 3 months before enrollment were analyzed. Warfarin and vitamin K levels were measured to adjust for confounders. Phenotypes were defined using the 'warfarin response index' (WRI) defined as INR divided by the daily maintenance warfarin dose. We tested SNPs in CYP2C9 (3 sites: 430C>T (rs1799853), 1075A>C (rs1057910), 1076T>C) and VKORC1 (14 sites: 381C>T, 861C>A (rs17880887), 2653G>C, 3673A>G, 5496G>T, 5808T>G (r17882154), 6009C>T, 6484T>C (rs9934438), 6853C>T (rs17886369), 7566T>C, 8767G>C, 8814T>C, 9041G>A (rs17880624), and 9071G>T) using a standard sequencing method. Multivariate linear regression analysis was applied to establish the formula for warfarin dosage.

Results

All 204 patients had excellent drug compliance. The mean INR was 2.22 (+0.56) and mean daily maintenance dose of warfarin was 3.92 mg (+1.54). Patients with low WRI were younger (P<0.001) with high body mass index (P=0.003), high prevalence of wild-type CYP2C9 polymorphism (1075A>C, P<0.001), and six heterozygote SNPs in VRORC1 (P<0.001), which were tightly interlinked (381T>C, 3673G>A, 6484T>C, 6853C>G. 7566C>T, 9041G>A) (r²=1). Based on these data, a warfarin dosing formula was established.

Conclusions

WRI is influenced by age, body mass index and SNPs in VKORC1 and CYP2C9 in Korean stroke patients. The obtained warfarin dosing formula may be clinically applicable.

Warfarin-antibiotic interactions in older adults of an outpatient anticoagulation clinic

BACKGROUND

Several classes of drugs, such as antibiotics, may interact with warfarin to cause an increase in warfarins anticoagulant activity and the clinical relevance of warfarin-antibiotic interactions in older adults is not clear.

OBJECTIVE

The aim of this study was to determine the effect of oral antibiotics, such as amoxicillin, azithromycin, cephalexin, ciprofloxacin, levofloxacin, and moxifloxacin, on the international normalized ratio (INR) in patients ≥65 years on stable warfarin therapy. The secondary objective was to compare the effect of warfarin-antibiotic interactions on outcomes of overanticoagulation.

METHODS

Data for this retrospective cohort study were collected through a medical record review of patients in an outpatient anticoagulation clinic of a Veterans Affairs medical center. Patients aged ≥65 years on stable warfarin therapy and with at least 1 prescription of an oral antibiotic of interest during the period from January 1, 2003 to March 1, 2011 were included. A mixed-effects repeated-measures ANOVA model was used to determine the effect of antibiotics on the mean change in patients' INR. The Fisher exact test was used to determine the association between the antibiotics and secondary outcomes of overanticoagulation, using cephalexin as the control. Statistical significance was defined as a P value <0.05.

RESULTS

A total of 205 patients had 364 prescriptions for warfarin and antibiotics concomitantly, and there was a significant interaction between antibiotic and time (F(15, 358) = 1.9; P = 0.0221). Antibiotics with a significant increase in INR were amoxicillin (P = 0.0019), azithromycin (P < 0.0001), ciprofloxacin (P = 0.002), levofloxacin (P < 0.0001) and moxifloxacin (P < 0.0001). There was a significant association between type of antibiotic and secondary outcomes of overanticoagulation.

CONCLUSIONS

In older patients on stable warfarin therapy, antibiotics may lead to an increase in INR. However, this may not result in clinically significant outcomes of bleeding or hospitalization, suggesting that antibiotics may be prescribed for older adults taking warfarin as long as their INR is being routinely monitored.

Bleeding peptic ulcer in the elderly: risk factors and prevention strategies

Peptic ulcer bleeding is a frequent and dramatic event with both a high mortality rate and a substantial cost for healthcare systems worldwide. It has been found that age is an independent predisposing factor for gastrointestinal bleeding, with the risk increasing significantly in individuals aged>65 years and increasing further in those aged>75 years. Indeed, bleeding incidence and mortality are distinctly higher in elderly patients, especially in those with co-morbidities. NSAID therapy and Helicobacter pylori infection are the most prevalent aetiopathogenetic factors involved in peptic ulcer bleeding. The risk of bleeding seems to be higher for NSAID- than for H. pylori-related ulcers, most likely because the antiplatelet action of NSAIDs impairs the clotting process. NSAID users may be classified as low or high risk, according to the absence or presence of one or more of the following factors associated with an increased risk of bleeding: co-morbidities; corticosteroid or anticoagulant co-therapy; previous dyspepsia, peptic ulcer or ulcer bleeding; and alcohol consumption. Different types of NSAIDs have been associated with different bleeding risk, but no anti-inflammatory drug, including selective cyclo-oxygenase (COX)-2 inhibitors, is completely safe for the stomach. Furthermore, even low-dose aspirin (acetylsalicylic acid) [<325 mg/day] and a standard dose of non-aspirin antiplatelet treatment (clopidogrel or ticlopidine) have been found to cause bleeding and mortality. No clear risk factor favouring H. pylori-related ulcer bleeding has been identified. Peptic ulcer bleeding prevention remains a challenge for the physician, but data are now available on use of a safer and cheaper strategy for both low- and high-risk patients. Unfortunately, despite the fact that several society and national guidelines have been formulated, these are poorly followed in clinical practice. Proton pump inhibitor (PPI) or misoprostol therapy and H. pylori eradication in NSAID-naive patients are the most commonly proposed strategies. Selective COX-2 inhibitor therapy in high-risk patients has also been suggested, but concerns over the possible cardiovascular adverse effects of some of these agents should be taken into account. Moreover, switching to selective COX-2 inhibitors in patients with previous bleeding is not completely risk free, and concomitant PPI therapy is also needed. H. pylori eradication is mandatory in all patients with peptic ulcer, and such an approach has been found to be significantly superior to PPI maintenance therapy. H. pylori eradication is frequently achieved with sequential therapy in elderly patients with peptic ulcer. In conclusion, upper gastrointestinal bleeding is a dramatic event with a high mortality rate, particularly in the elderly. Some effective preventative strategies are now available that should be implemented in clinical practice.

Individualizing warfarin therapy

Warfarin is the most commonly prescribed oral anticoagulant for the treatment and prevention of thromboembolic events. The correct maintenance dose of warfarin for a given patient is difficult to predict, the drug carries a high risk of toxicity, and variability among patients means that the safe dose range differs widely between individuals. Recent pharmacogenetic studies indicate that the routine incorporation of genetic testing into warfarin therapy protocols could substantially ease both the financial and health risks currently associated with this treatment. In particular, the variability in warfarin dose requirement is now recognized to be due, in large part, to polymorphisms in two genes: cytochrome P450 2C9 and the vitamin K epoxide reductase complex subunit 1. The development of algorithms that integrate all of the relevant genetic and physical factors into comprehensive, individualized predictive models for warfarin dose could be used to translate the results of pharmacogenetic testing into actionable clinical application.

The risks of warfarin use in the elderly

The use of warfarin in the elderly, particularly for stroke prevention in chronic atrial fibrillation, is steadily increasing. Although the benefits of warfarin are greatest in the elderly, so are the risk of adverse outcomes and the difficulties of anticoagulant management. Clinical systems need to improve to counter this therapeutic dilemma, as warfarin is likely to remain the only widely available oral anticoagulant for the foreseeable future. Aspects that require attention are: the careful selection of patients in whom treatment with warfarin is appropriate; initiating therapy in a low dose (e.g., 2.5-5 mg/day); thorough education of patients and carers; close monitoring, especially with any change in the patient's regular drug therapy; involving patients more in the management of their warfarin therapy (self-monitoring/management in suitable patients); and ongoing review of the appropriateness of therapy as circumstances change.

Management of oral anticoagulant in clinical practice: a retrospective study of 187 patients

Oral anticoagulant (OA) therapy is widely used in elderly patients because of the increase of indications with age (venous thromboembolism and atrial fibrillation). A particularity of France is to administer three different OAs (warfarin and more often fluindione or acenocoumarol). In an attempt to assess the particularities of managing all three OAs in elderly patients in clinical practice, we studied the modalities of anticoagulation of 187 consecutive OA therapy patients (mean age = 74.4 years) hospitalized in an Internal Medicine department (95 patients on OA at admission and 92 patients initiated on OA during hospitalization). Patients aged 75 years or older more often required a low dosage of OA than those aged younger than 75, irrespective of the OA (warfarin and more often fluindione or acenocoumarol). Ambulatory patients aged 75 years or older were more susceptible to receive acenocoumarol than were ambulatory patients younger than 75 years (respectively 30/67 vs 8/28, respectively), whereas fluindione was prescribed at the same frequency in ambulatory patients and hospitalized patients, regardless of age group (> or =75: 32/67; <75: 19/28). In hospitalized patients with OA induction, fluindione was prescribed as often in patients younger than 75 than in patients aged 75 years or older (40/47 vs 35/45, respectively). On admission, international normalized ratio was in the target range in 26 of the 95 patients (27.4%) and was >3 in 51 of the 95 patients (51.6%). OA therapy was stopped during hospitalization in 35 patients (36.8%). In conclusion, we have a picture of the practice of anticoagulation with three different OA therapies. Although it is usually recommended to prescribe long half-time OA therapy (2), it appears that short half-time therapy such as acenocoumarol still represents an important number of OA prescriptions in France, especially in ambulatory and elderly patients. International normalized ratio is not in the target range as often as expected in clinical practice, and elderly patients require specific modalities of OA therapy management, such as half dose initiation, use of long-half-life OA, and close monitoring.

Cognitive Impairment as Determinant for Sub-Optimal Control of Oral Anticoagulation Treatment in Elderly Patients with Atrial Fibrillation

BACKGROUND AND OBJECTIVE

Atrial fibrillation is an indication for oral anticoagulation treatment. Maintaining the International Normalized Ratio (INR) within the therapeutic range minimises thromboembolic and bleeding complications. We have investigated whether cognitive capacity affects control of anticoagulation in elderly patients with atrial fibrillation.

PATIENTS AND METHODS

A retrospective study was conducted to investigate the association between cognitive impairment and control of anticoagulation. Patients > or =70 years of age with atrial fibrillation using acenocoumarol (nicoumalone) as anticoagulant were included. All patients were monitored by the Anticoagulation Clinic in the Midden-Brabant region in the Netherlands. The cognitive function of all patients was assessed using the Mini-Mental State Examination (MMSE) on the index date. INR values were obtained from the year preceding the index date. Patients with an MMSE score <23 were defined as cognitively impaired. The primary outcome of the study was the incidence of an INR value within the therapeutic range of 2.0-3.4 during < or =70% of treatment time in the year prior to the cognitive function assessment. The secondary endpoint was the number of patients with an INR <2.0 or > or =6.0 at least once during this year. Logistic regression analysis was used to evaluate the association between cognitive function and control of anticoagulation.

RESULTS

A total of 152 patients were included in the study. An MMSE score <23 was associated with an inadequate INR control (odds ratio [OR] 2.77; 95% CI 1.13, 6.74). After correction for hospital admission and change of possibly interacting medication (both also associated with inadequate INR control), this association remained statistically significant. Significantly more patients with an MMSE score <23 had one or more INR values of six or higher (OR 3.06; 95% CI 1.14, 8.18).

CONCLUSION

In elderly people with atrial fibrillation using oral anticoagulation, an MMSE score <23 is independently associated with an inadequate INR control, mainly because of an increased number of supratherapeutic INR values. This finding should be taken into account when making decisions about use of oral anticoagulants in the elderly.

Drug interactions in gastroenterology: mechanisms, consequences, and how to avoid

Drug interactions are an important avoidable cause of illness. With an increasing array of medications available to treat human disease and an increasing number of patients taking many medications, the risk of clinically significant drug interactions increases. This review describes some examples of common drug interactions in gastroenterology. The underlying mechanisms are discussed, and strategies are proposed to avoid drug interactions in clinical practice.

Anticoagulation for non-valvular atrial aibrillation - towards a new beginning with ximelagatran

OBJECTIVES: Ximelagatran is a novel oral direct thrombin inhibitor. It has favorable pharmacodynamic properties, with a broad therapeutic range without the need for anticoagulation monitoring. We aimed to discover whether ximelagatran offers a genuine future replacement to warfarin for patients in persistent atrial fibrillation (AF). MATERIALS AND METHODS: We provide an evidence-based review of the relative merits and disadvantages of warfarin and aspirin. We subsequently present an overview of the evidence for the utility of ximelagatran in the treatment of AF. RESULTS: Adjusted dose warfarin is recommended over aspirin for patients in AF at high risk of future stroke. Some of this benefit is partially offset by the higher bleeding risks associated with warfarin therapy. The SPORTIF III and V studies have shown that ximelagatran is not inferior to warfarin in the prevention of all strokes in patients with AF (both persistent and paroxysmal). This benefit was partially offset by the finding of a significant elevation of liver transaminases (>3 x normal) in 6% of patients. CONCLUSIONS: Current data would suggest that ximelagatran might represent a future alternative to warfarin. The lack of need for anticoagulant monitoring has been partially offset by a need for regular monitoring of liver function. Further data from randomized clinical trials is clearly needed.

The prevalence of various arrhythmias in normotensive and hypertensive elderly patients

The prevalence of the most frequent arrhythmias was studied in a geriatric day hospital. Patients older than 65 years have been considered, of them 118 were normotensive and 56 hypertensive subjects. Comparison of the two groups revealed no statistically significant difference either in the frequency of occurrence or in the type of arrhythmias. Dividing the hypertensive patients in the Lown's classes, only those of class 3 or over displayed a considerably higher frequency of arrhythmias than the normotensive subjects. The results demonstrate the age-dependent increase of the prevalence of arrhythmias in general, and the increased occurrence of complex ventricular types in the hypertensive subjects.

Large variations in the use of oral anticoagulants in stroke patients with atrial fibrillation: a Swedish national perspective

OBJECTIVES

To explore nation-wide use of anticoagulation in stroke patients with atrial fibrillation, in routine clinical practice in Sweden.

DESIGN

Cross-sectional cohort study.

SETTING

Patients included in Riks-Stroke, the Swedish national quality register for stroke care, during 2001.

SUBJECTS

Hospitals with incomplete coverage were excluded, leaving 4538 stroke patients with atrial fibrillation amongst 18 276 stroke patients from 75 hospitals in six health care regions.

MAIN OUTCOME MEASURE

Treatment with oral anticoagulants.

RESULTS

At stroke onset, the proportion of patients with atrial fibrillation and first-ever stroke, receiving oral anticoagulants as primary prevention was 11.0% (range 8.4-13.5% between regions and 2.5-24.4% between hospitals). Younger age, male sex and diabetes at stroke onset independently predicted primary prevention with oral anticoagulants. The proportion of stroke patients with atrial fibrillation receiving oral anticoagulants as secondary prevention at discharge was 33.5% (range 29.9-40.6% between regions and 16.4-61.9% between hospitals). Independent predictors for secondary prevention were younger age, male sex and independent activities of daily life (ADL) function before the stroke, being discharged to home, being fully conscious on admission and health care region.

CONCLUSION

There were variations between hospitals and regions that differences in age, sex, functional impairments and comorbidities could not fully explain. This indicates that evidence-based primary and secondary prevention of embolic stroke is insufficiently practised. Local factors seem to determine whether patients with atrial fibrillation gain access to optimal prevention of stroke or not.

Evaluation of a warfarin initiation protocol for older people

A protocol for initiation of warfarin therapy, targeted specifically for older people and based on individual responses to initial warfarin doses, was evaluated in a case-control study. People within the protocol group: (i) received higher initial doses of warfarin, (ii) reached an international normalized ratio (INR) of 2 more quickly, (iii) spent more time with INR of 2-3 in the first week and (iv) were less likely to be over-anticoagulated. However, the proportion of people who reached an INR of 2 too quickly (in <4 days) was no greater. The protocol correctly predicted the maintenance dose range of warfarin in over 70% of cases.

Getting to the heart of atrial fibrillation

Review a management plan for atrial fibrillation, using cardiology association guidelines and standards.

Atrial fibrillation in the elderly: facts and management

Although atrial fibrillation is not widely known by the general public, in developed countries it is the most common arrhythmia. The incidence increases markedly with advancing age. Thus, with the growing proportion of elderly individuals, atrial fibrillation will come to represent a significant medical and socioeconomic problem. The consequences of atrial fibrillation have the greatest impact. The risk of thromboembolism is well known; other outcomes of atrial fibrillation are less well recognised, such as its relationship with dementia, depression and death. Such consequences are responsible for diminished quality of life and considerable economic cost. Atrial fibrillation is characterised by rapid and disorganised atrial activity, with a frequency between 300 and 600 beats/minute. The ventricles react irregularly, and may contract rapidly or slowly depending on the health of the conduction system. Clinical symptoms are varied, including palpitations, syncope, dizziness or embolic events. Atrial fibrillation may be paroxysmal, persistent or chronic, and a number of attacks are asymptomatic. Suspicion or confirmation of atrial fibrillation necessitates investigation and, as far as possible, appropriate treatment of underlying causes such as hypertension, diabetes mellitus, hypoxia, hyperthyroidism and congestive heart failure. In the evaluation of atrial fibrillation, cardiac exploration is invaluable, including electrocardiogram (ECG) and echocardiography, with the aim of detecting cardiac abnormalities and directing management. In elderly patients (arbitrarily defined as aged >75 years), the management of atrial fibrillation varies; it requires an individual approach, which largely depends on comorbid conditions, underlying cardiac disease, and patient and physician preferences. This management is essentially based on pharmacological treatment, but there are also nonpharmacological options. Two alternatives are possible: restoration and maintenance of sinus rhythm, or control of ventricular rate, leaving the atria in arrhythmia. Pharmacological options include antiarrhythmic drugs, such as class III agents, beta-blockers and class IC agents. These drugs have some adverse effects, and careful monitoring is necessary. The nonpharmacological approach to atrial fibrillation includes external or internal direct-current cardioversion and new methods, such as catheter ablation of specific foci, an evolving science that has been shown to be successful in a very select group of atrial fibrillation patients. Another serious challenge in the management of chronic atrial fibrillation in older individuals is the prevention of stroke, its primary outcome, by choosing an appropriate antithrombotic treatment (aspirin or warfarin). Several risk-stratification schemes have been validated and may be helpful to determine the best antithrombotic choice in individual patients.

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.

Thrombocytopenia in patients receiving oral anticoagulant therapy

The aim of this report was to determine the frequency of thrombocytopenia in a cohort of 1,126 patients receiving oral anticoagulant therapy (OAT), and to compare the grade of thrombocytopenia and the severity of bleeding complications. Severe thrombocytopenia was observed in five patients, and moderate and light thrombocytopenia were observed in 208 patients. Thrombocytopenic patients receiving OAT presented five major and six minor hemorrhages. The presence of hepatitis markers and autoantibodies was assessed. All parameters at the time of the bleeding complication were in the therapeutic range.