Should aspirin be continued in patients started on warfarin?

The prescription of antiplatelet medication in a very elderly population: An observational study in 15 141 ambulatory subjects

OBJECTIVE

Despite the frequent use of antiplatelet medication (AM) in the elderly patients, very few studies have investigated its prescription. We describe AM prescription through retrospective study in ambulatory elderly patients.

METHOD

All subjects aged over 80 years with a medical prescription delivered in March 2015 and affiliated to the Mutualité Sociale Agricole de Bourgogne. Subjects with prescriptions for AM were compared with those without.

RESULTS

A total of 15 141 ambulatory elderly patients (83-89 years, 61.3% of women) were included and 4412 (29.14%) had a prescription for AM. The latter were more frequently men than those without AM (43% vs 36.93%, P < .0001) and more frequently had chronic comorbidities (77.24% vs 64.65%, P < .0001). Compared with ambulatory subjects without AM, those with AM more frequently had coronary heart disease (35.15% vs 14.49%), severe hypertension (30% vs 25.65%), diabetes (27.42% vs 20.64%), peripheral arterial diseases (16.28% vs 5.96%) and disabling stroke (9% vs 5.56% (all P < .0001). In addition, they had more prescriptions of beta-blockers (45.24% vs 36.90%), angiotensin conversion enzyme inhibitor (31.35% vs 25.44%), calcium channel blockers (33.34% vs 27.90%), nitrate derivatives (10.6% vs 6.03%) or hypolipidemic agents (HA; 49.81% vs 29.72%) (all P < .0001) than those without AM.

CONCLUSION

In this study, which is very interested for its size and the advanced age of the subjects, long-course AM was prescribed in one third of ambulatory elderly patients. Coronary heart disease, severe hypertension and diabetes were more frequent in AM subjects. However, the low percentage of declared strokes was surprising. We provide additional data to doctors following subjects with AM.

The mortality reducing effect of aspirin in colorectal cancer patients: Interpreting the evidence

In 1971 the first study appeared that suggested a relationship between aspirin and cancer. Currently publications on the subject of aspirin and cancer are numerous, with both a beneficial effect of aspirin on cancer incidence and a beneficial effect on cancer survival. This review focusses on the relation between the use of aspirin and improved survival in colorectal cancer patients. Various study designs have been used, with the main part being observational studies and post hoc meta-analyses of cancer outcomes in cardiovascular prevention trials. The results of these studies are unambiguously pointing towards an effect of aspirin on colorectal cancer survival, and several randomised controlled trials are currently ongoing. Some clinicians feel that the current evidence is conclusive and that the time has come for aspirin to be prescribed as adjuvant therapy. However, until this review, not much attention has been paid to the specific types of bias associated with these studies. One of these biases is confounding by indication, because aspirin is indicated for patients as secondary prevention for cardiovascular disease. This review aims to provide perspective on these biases and provide tools for the interpretation of the current evidence. Albeit promising, the current evidence is not sufficient to already prescribe aspirin as adjuvant therapy for colorectal cancer.

Economic Evaluation of the Combined Use of Warfarin and Low-dose Aspirin Versus Warfarin Alone in Mechanical Valve Prostheses

BACKGROUND

The use of combined therapy of antiplatelet and anticoagulant versus anticoagulant alone to reduce instances of thromboembolic events in patients with heart valve prostheses is an established standard of care in many countries but not in Egypt. A previous Markov model cost-effectiveness study on Egyptian patients aged 50-60 years demonstrated that the combined therapy reduces the overall treatment cost. However, due to the lack of actual real-world data on cost-effectiveness and the limitation of the Markov model study to 50- to 60-year-old patients, the Egyptian medical community is still questioning whether the added benefit is worth the cost.

OBJECTIVE

To assess, from the perspective of the Egyptian health sector, the cost-effectiveness of the combined use of warfarin and low-dose aspirin (75 mg) versus that of warfarin alone in patients with mechanical heart valve prostheses who began therapy between the age of 15 and 50 years.

METHODS

An economic evaluation was conducted alongside a randomized, controlled trial to assess the cost-effectiveness of the combined therapy in patients with mechanical valve prostheses. A total of 316 patients aged between 15 and 50 years were included in the study and randomly assigned to a group treated with both warfarin and aspirin or a group treated with warfarin alone.

RESULTS

The patients in the combined therapy group exhibited a significantly longer duration of protection against the first event. Fewer primary events were observed in the patients treated with warfarin plus aspirin than in those treated with warfarin alone (1.4 %/year, vs. 4.8 %/year), and a higher mean quality-adjusted life-years (QALYs) value over 4 years was obtained for the group treated with warfarin plus aspirin (difference 0.058; 95 % CI 0.013-0.118), although this difference did not reach a conventional level of statistical significance. The total costs over a 4-year period were lower with the combined therapy (difference -US$244; 95 % CI -US$483.1 to -US$3.8), which yielded an incremental cost-effectiveness ratio of -US$4206 per QALY gained. Thus, the combined therapy was dominant. All costs were reported in US dollars (USD) for the financial year 2014.

CONCLUSIONS

The results of this analysis indicate that from the perspective of the Egyptian health sector, the addition of aspirin to the typical warfarin therapy is more effective and less costly for patients with mechanical valve prostheses than treatment with warfarin alone. This combined strategy could be adopted to prevent the complications of mechanical valve prostheses. Our study adds to the body of evidence supporting the option of warfarin-plus-aspirin therapy for patients with mechanical valve prostheses.

Inappropriate prescribing of antithrombotic therapy in Ethiopian elderly population using updated 2015 STOPP/START criteria: a cross-sectional study

Background

Inappropriate use of antiplatelets and anticoagulants among elderly patients increases the risk of adverse outcomes. The aim of this study was to assess the prevalence of inappropriate prescribing of antithrombotic therapy in hospitalized elderly patients.

Methods

A retrospective cross-sectional, single-center study was conducted at the Gondar University Hospital. A total of 156 hospitalized elderly patients fulfilling the inclusion/exclusion criteria were included in the study. The Screening Tool for Older Person’s Prescription/Screening Tool to Alert doctors to Right Treatment criteria version 2 were applied to patients’ data to identify the total number of inappropriate prescribing (IPs) including potentially inappropriate medications and potential prescribing omissions.

Results

A total of 70 IPs were identified in 156 patients who met the inclusion criteria. Of these, 36 (51.4%) were identified as potentially inappropriate medications by the Screening Tool for Older Person’s Prescription criteria. The prevalence of IP per patient indicated that 58 of the 156 (37.2%) patients were exposed to at least one IP. Of these, 32 (55.2%) had at least one potentially inappropriate medication and 33 (56.9%) had at least one potential prescribing omission. Patients hospitalized due to venous thromboembolism (adjusted odds ratio [AOR] =29.87, 95% confidence interval [CI], 1.26–708.6), stroke (AOR =7.74, 95% CI, 1.27–47.29), or acute coronary syndrome (AOR =13.48, 95% CI, 1.4–129.1) were less likely to be exposed to an IP. An increase in Charlson comorbidity index score was associated with increased IP exposure (AOR =0.60, 95% CI, 0.39–0.945). IPs were about six times more likely to absent in patients prescribed with antiplatelet only therapy (AOR =6.23, 95% CI, 1.90–20.37) than those receiving any other groups of antithrombotics.

Conclusion

IPs are less common in elderly patients primarily admitted due to venous thromboembolism, stroke, and acute coronary syndrome, and those elderly patients prescribed with only antiplatelet. Patients with higher Charlson comorbidity index were, however, associated with increased IPs exposure. Our study may guide further research to reduce high-risk prescription of antithrombotics in the elderly.

Patient-Centred Care of Older Adults With Cardiovascular Disease and Multiple Chronic Conditions

Multimorbidity, defined as the presence of 2 or more chronic conditions, is common among older adults with cardiovascular disease. These individuals are at increased risk for poor health outcomes and account for a large proportion of health care utilization. Clinicians are challenged with the heterogeneity of this population, the complexity of the treatment regimen, limited high-quality evidence, and fragmented health care systems. Each treatment recommended by a clinical practice guideline for a single cardiovascular disease might be rational, but the combination of all evidence-based recommendations can be impractical or even harmful to individuals with multimorbidity. These challenges can be overcome with a patient-centred approach that incorporates the individual's preferences, relevant evidence, the overall and condition-specific prognosis, clinical feasibility of treatments, and interactions with other treatments and coexisting chronic conditions. The ultimate goal is to maximize benefits and minimize harms by optimizing adherence to the most essential treatments, while acknowledging trade-offs between treatments for different health conditions. It might be necessary to discontinue therapies that are not essential or potentially harmful to decrease the risk of drug-drug and drug-disease interactions from polypharmacy. A decision to initiate, withhold, or stop a treatment should be on the basis of the time horizon to benefits vs the individual's prognosis. In this review, we illustrate how cardiologists and general practitioners can adopt a patient-centred approach to focus on the aspects of cardiovascular and noncardiovascular health that have the greatest effect on functioning and quality of life in older adults with cardiovascular disease and multimorbidity.

Cost-Effectiveness of the Combined Use of Warfarin and Low-Dose Aspirin versus Warfarin Alone in Egyptian Patients with Aortic Valve Replacements: A Markov Model

BACKGROUND

The combination of antiplatelet and anticoagulant therapy significantly reduces the rate of thromboembolic events in patients with heart valves compared with anticoagulant therapy alone. Cost-effectiveness of this therapy in Egypt, however, has not yet been established.

OBJECTIVE

The aim of the present study was to evaluate the cost-effectiveness of the combined use of warfarin and low-dose aspirin (100 mg) versus warfarin alone in patients with mechanical aortic heart valve prostheses who began therapy at the age of 50 to 60 years over a 5-year period from the perspective of the medical providers.

METHODS

A cohort Markov process model with five health states (recovery, reoperation, bleeding, thromboembolism, and death) based on Egyptian clinical practice was derived from published sources. The clinical parameters were derived from meta-analyses of randomized controlled trials of patients with mechanical valve prostheses. The quality of life of the health states was derived using the available published data. Direct medical costs were obtained from four top-rated governmental cardiology hospitals in Egypt. All costs and effects were discounted at 3.5% annually. All costs were converted using the purchasing power parity rate and are reported in US $ for the financial year of 2013.

RESULTS

The total quality-adjusted life-years (QALYs) were estimated to be 1.1616 and 1.1199 for the warfarin plus aspirin group and the warfarin group, respectively, which resulted in a difference of 0.0416 QALYs. The total costs for the warfarin plus aspirin group and the warfarin group were US $307.33 and US $315.25, respectively (the difference was US $7.92), which yielded an incremental cost-effectiveness ratio of -190.38 for the warfarin plus aspirin group. Thus, the combined therapy was dominant. Various one-way sensitivity analyses indicated that probabilities of reoperation and bleeding in the recovery state had the greatest effects on incremental costs. The model parameters that had the greatest effects on incremental QALYs were the relative risk reduction of death and the utility value in the recovery state.

CONCLUSIONS

The present study is the first cost-utility analysis to conclude that, from the perspective of Egyptian medical providers, combined therapy is more effective and less costly than warfarin alone for patients with mechanical aortic valve prostheses. For clinicians and patients who choose to focus on minimizing thromboembolic risk, these results suggest that combined therapy offers the best protection. This study helps to inform decisions about the allocation of health care system resources and to achieve better health in the Egyptian population.

Antithrombotic medication use and bleeding risk in medically ill patients after hospitalization

BACKGROUND

Hospitalized medically ill patients receiving antithrombotic medications experience increased risk of bleeding. We examined antithrombotic use, bleeding rates, and associated risk factors at 30 days post discharge.

METHODS

This retrospective database analysis included nonsurgical patients aged ≥40 years hospitalized for ≥2 days during 2005 to 2009. Previously cited, validated International Classification of Diseases, Ninth Revision, Clinical Modification codes for major bleeding were used to define clinically relevant bleeding.

RESULTS

Of the 327,578 patients, 9.1% received antithrombotic medications, of which 3.7% were anticoagulants. Rates of major and minor bleeding were 1.8% and 7.1%, respectively. Preindex gastroduodenal ulcer, thromboembolic stroke, blood dyscrasias, liver disease, and rehospitalization were the strongest predictors of major bleeding. Other risk factors included increasing age, male gender, and hospital stay of ≥3 days.

CONCLUSIONS

Careful consideration of these demonstrated bleed-associated comorbidities before initiating anticoagulation or combining antithrombotic medications in medically ill patients may improve strategies for prevention of postdischarge thromboembolism.

Evaluation of drug-drug interaction screening software combined with pharmacist intervention

BACKGROUND

Drug-drug interactions (DDI) in hospitalized patients are highly prevalent and an important source of adverse drug reactions. DI computerized screening system can prevent the occurrence of some of these events.

OBJECTIVE

To evaluate the impact of drug-drug interaction (DDI) screening software combined with active intervention in preventing drug interactions.

SETTING

The study was conducted at General Hospital of Vitória da Conquista (HGVC), Brazil.

METHOD

A quasi-experimental study was used to evaluate the impact of IM-Pharma, a locally developed drug-drug interaction screening system, coupled with pharmacist intervention on adverse drug events in the hospital setting.

MAIN OUTCOME MEASURE

The proportion of patients co-prescribed two interacting drugs were measured in two phases, prior the implementation of IM-Pharma and during the intervention period. DDI rates per 100 patient days were calculated before and after implementation. Risk ratios were estimated by Poisson regression models.

RESULTS

A total of 6,834 instances of drug-drug interactions were identified; there was an average of 3.3 DDIs per patient in phase one and 2.5 in phase two, a reduction of 24 % (P = 0.03). There was a 71 % reduction in high-severity drug-drug interaction (P < 0.01). The risk for all DDIs decreased 50 % after the implementation of IM-Pharma (P < 0.01), and for those with high-severity, the reduction was 81 % (P < 0.01).

CONCLUSION

The performance of IM-Pharma combined with pharmacist intervention was positive with an expressive reduction in the risk of DDIs.

Anticoagulation Review

Anticoagulants, also known as antithrombotics, are among the most commonly prescribed medications in the United States. Understanding how these medications work, the propensity for interactions with other drugs, dietary factors, and disease states is important for clinicians assessing and providing care to patients in all environments. In this review, we seek to provide essential information for the home health care provider for evaluating patients receiving anticoagulants commonly prescribed in the home health care setting. The low-molecular-weight heparins and vitamin K antagonists are the most commonly used agents for outpatient anticoagulation. New agents, such as the direct factor Xa inhibitors and direct thrombin inhibitors have recently been approved with additional new agents in the approval process and development pipeline. We seek to review the most pertinent information for each of these classes of medications providing information on pharmacology, interactions with other drugs, diet, and diseases and important clinical information.

Aspirin- and clopidogrel-associated bleeding complications: data mining of the public version of the FDA adverse event reporting system, AERS

OBJECTIVE

Adverse event reports (AERs) submitted to the US Food and Drug Administration (FDA) were reviewed to assess the bleeding complications induced by the administration of antiplatelets and to attempt to determine the rank-order of the association.

METHODS

After a deletion of duplicated submissions and the revision of arbitrary drug names, AERs involving warfarin, aspirin, cilostazol, clopidogrel, ethyl icosapentate, limaprost alfadex, sarpogrelate, and ticlopidine were analyzed. Authorized pharmacovigilance tools were used for the quantitative detection of signals, i.e., drug-associated adverse events, including the proportional reporting ratio, the reporting odds ratio, the information component given by a Bayesian confidence propagation neural network, and the empirical Bayes geometric mean.

RESULTS

Based on 22,017,956 co-occurrences, i.e., drug-adverse event pairs, found in 1,644,220 AERs from 2004 to 2009, 736 adverse events were listed as warfarin-associated adverse events, and 147 of the 736 were bleeding complications, including haemorrhage and haematoma. Both aspirin and clopidogrel were associated with haemorrhage, but the association was more noteworthy for clopidogrel. As for bleeding complications related to the gastrointestinal system, e.g., melaena and haematochezia, the statistical metrics suggested a stronger association for aspirin than clopidogrel. The total number of co-occurrences was not large enough to compare the association with bleeding complications for the other 5 antiplatelets.

CONCLUSIONS

The data strongly suggest the necessity of well-organized clinical studies with respect to antiplatelet-associated bleeding complications.

Antithrombotic therapies in patients with prosthetic heart valves: guidelines translated for the clinician

Patients with prosthetic heart valves require chronic oral anticoagulation. In this clinical scenario, physicians must be mindful of the thromboembolic and bleeding risks related to chronic anticoagulant therapy. Currently, only vitamin K antagonists are approved for this indication. This paper reviews the main heart valve guidelines focusing on the use of oral anticoagulation in these patients.

Effectiveness and safety of combined antiplatelet and anticoagulant therapy: a critical review of the evidence from randomized controlled trials

Antiplatelet and anticoagulant drugs are effective for the prevention of arterial and venous thrombosis but patients continue to experience major cardiovascular events despite their use. Strategies to improve the effectiveness of antithrombotic therapies include selecting the optimal drug and dosing regimen, the use of combinations of antiplatelet and anticoagulant drugs and the development of new more effective drugs to replace existing therapies. Evidence from randomized controlled trials indicates that the combination of aspirin and an anticoagulant is more effective than aspirin alone for the prevention of recurrent cardiovascular events in patients with acute coronary syndrome and is more effective than anticoagulation alone for the prevention of thromboembolic events in patients with mechanical heart valves, but at a cost of increased bleeding. Randomized controlled trials provide no evidence for improved effectiveness of combination therapy compared with antiplatelet therapy alone for the prevention of recurrent cardiovascular events in patients with non-cardioembolic stroke or peripheral artery disease, or compared with anticoagulant therapy alone for the prevention of stroke in patients with atrial fibrillation. Despite lack of evaluation in randomized controlled trials, combination therapy is commonly used in patients with separate indications for antiplatelet therapy (e.g., acute coronary syndrome, recent coronary artery stent) and anticoagulant therapy (e.g., atrial fibrillation with at least one additional risk factor for stroke). Randomized trials are urgently required to evaluate the effectiveness and safety of combining antiplatelet and anticoagulant therapy in these settings.

Antithrombotic management of patients with prosthetic heart valves: current evidence and future trends

Over 4 million people worldwide have received a prosthetic heart valve, and an estimated 300,000 valves are being implanted every year. Prosthetic heart valves improve quality of life and survival of patients with severe valvular heart disease, but the need for antithrombotic therapy to prevent thrombotic complications in valve recipients poses challenges for clinicians and patients. Here, we review antithrombotic therapies for patients with prosthetic heart valves and management of thromboembolic complications. Advances in antithrombotic therapy and valve technologies are likely to improve the management of patients with prosthetic heart valves in developed countries, but the most important unmet need and potential for benefit from these new therapies is in developing countries where a massive and rapidly increasing burden of valvular heart disease exists.

Known knowns and known unknowns: risks associated with combination antithrombotic therapy

BACKGROUND

Use of antiplatelet therapy in combination with oral anticoagulants remains controversial. The purpose of this article is to review current consensus recommendations for antithrombotic therapy, to evaluate risks for bleeding among patients taking combination antithrombotic therapy, and lastly to review single-center data from Kaiser Permanente Colorado detailing clinical outcomes associated with combination therapy.

METHODS

This was a retrospective, longitudinal pharmacoepidemiologic review. Adult patients receiving warfarin managed by a clinical pharmacy service who had documented antiplatelet (aspirin, clopidogrel, and/or dipyridamole) use (combination therapy cohort) or non-use (monotherapy cohort) were identified as of September 30, 2005. Utilizing integrated, electronic medical records, anticoagulation-related adverse events (death, hemorrhage, thrombosis) and coronary events were identified during a six-month follow-up (October 2005 through March 2006). Proportions of events were compared between cohorts. Independent associations between the cohorts and the outcomes were assessed with adjustment for potential confounding factors.

RESULTS

Data from 2,560 monotherapy and 1,623 combination therapy patients were analyzed. Patients in the combination therapy cohort were more likely to have had anticoagulation-related hemorrhages (4.2% vs. 2.0%, unadjusted p<0.001). With adjustment, combined warfarin and antiplatelet use was independently associated with hemorrhagic (OR=2.75; 95% CI 1.44, 5.28) but not coronary (OR=0.99; 95% CI 0.37, 2.62) events.

CONCLUSIONS

At the population level, the hemorrhagic risk associated with warfarin therapy combined with antiplatelet therapy appears to outweigh the benefits. These findings suggest that clinicians carefully consider risks and benefits when prescribing antiplatelet therapy for patients taking warfarin who do not meet evidence-based criteria for that approach.

Concomitant antiplatelet and anticoagulation therapy: indications, controversies and practical advice

The use of combination antiplatelet and anticoagulant therapy is commonly encountered in clinical practice and is often a source of clinical controversy in regards to the efficacy versus the safety of this regimen. The benefit of combination therapy relates to the probable additive effect of suppressing both platelet and coagulation factor activities. The risk of dual therapy is the potential for increased hemorrhagic events which may outweigh the clinical benefit. This review will focus on the clinical evidence that has demonstrated greater efficacy with combination therapy over either antiplatelet or anticoagulant therapy alone. Clinicians should consider the importance of documentation of combination therapy use in their patients in an effort to target those patients with the greatest benefit, and to avoid unnecessary complications.

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.

How we diagnose and treat thrombotic manifestations of the antiphospholipid syndrome: a case-based review

Antiphospholipid antibodies including anticardiolipin antibodies, lupus anticoagulants, and anti–β2 glycoprotein-1–specific antibodies may identify patients at elevated risk of first or recurrent venous or arterial thromboembolism. Traditionally, published case series supplemented by anecdotal experience have formed the basis of management of patients with these autoantibodies. Over the past several years, studies have described the management of patients with key clinical manifestations of antiphospholipid antibodies, including patients with antiphospholipid antibody syndrome. As a result, evidence-based treatment recommendations are possible for selected patients with, or at risk of, thrombosis in the setting of antiphospholipid antibodies. Unfortunately, most patients encountered in clinical practice do not correspond directly with those enrolled in clinical trials. For such patients, treatment recommendations are based on experience, extrapolation, and less rigorous evidence. This article proposes 5 cases typical of those found in clinical practice and provides recommendations for therapy focused on a series of clinical questions. Whenever possible, the recommendations are based on evidence; however, in many cases, insufficient evidence exists, so the recommendation is experiential.

Combined antiplatelet and anticoagulant therapy: clinical benefits and risks

The combination of anticoagulant and antiplatelet therapy is more effective than antiplatelet therapy alone for the initial and long-term management of acute coronary syndromes but increases the risk of bleeding. Antiplatelet therapy is often combined with oral anticoagulants in patients with an indication for warfarin therapy (e.g. atrial fibrillation) who also have an indication for antiplatelet therapy (e.g. coronary artery disease) but the appropriateness of such an approach is unresolved. Anticoagulation appears to be as effective as antiplatelet therapy for long-term management of acute coronary syndrome and stroke, and possibly peripheral artery disease, but causes more bleeding. Therefore, in such patients who develop atrial fibrillation, switching from antiplatelet therapy to anticoagulants might be all that is required. The combination of anticoagulant and antiplatelet therapy has only been proven to provide additional benefit over anticoagulants alone in patients with prosthetic heart valves. The combination of aspirin and clopidogrel is not as effective as oral anticoagulants in patients with atrial fibrillation, whereas the combination of aspirin and clopidogrel is more effective than oral anticoagulants in patients with coronary stents. Whether the benefits of triple therapy outweigh the risks in patients with atrial fibrillation and coronary stents requires evaluation in randomized trials.

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.

Ocular bleeding related to warfarin anticoagulation in patients with mechanical heart valve and atrial fibrillation

We investigated the incidence of ocular bleeding in patients taking anticoagulant therapy (warfarin) and its association with other related factors. We examined 210 patients taking warfarin and 210 gender- and age-matched controls for ocular bleeding. Patients and controls were examined by external ocular examination and fundoscopic examination. The incidence of ocular bleeding was 11.4% in patients and 3.8% in controls. It was five times higher in patients with hypertension than in other patients. The incidence of ocular bleeding was higher in older than in younger patients. No association was found between ocular bleeding and factors such as gender, international normalized ratio, duration of warfarin therapy, concomitant aspirin use and diabetes mellitus. Thus, warfarin therapy increases the frequency of ocular bleeding. The higher incidence of ocular bleeding in the patients with hypertension and advanced age should be kept in mind and this subgroup of patients taking warfarin should be monitored closely.

Managing Complications of Anticoagulant Therapy

Understanding the frequency, risk factors, and management of anticoagulant-induced adverse events will assist clinicians in optimizing patient outcomes. The most frequent adverse event of all anticoagulants is major bleeding. Risk factors for major bleeding have been identified with the heparin compounds, the direct thrombin inhibitors (DTIs), fondaparinux, and warfarin therapy. Understanding these risk factors can help prevent bleeding events. For cases of clinically significant bleeding, reversal agents exist primarily for heparin and warfarin. Although less common, nonbleeding adverse events of anticoagulant therapy can also be life threatening. The heparin compounds are associated with the development of heparin-induced thrombocytopenia (HIT) and osteoporosis. HIT can result in life-threatening thrombosis and is usually managed with a DTI. Nonbleeding adverse events with warfarin therapy include skin reactions and the development of venous limb gangrene. Appropriate initiation of warfarin therapy may decrease the risk of venous limb gangrene.