Warfarin Use In Atrial Fibrillation Research Articles

Patient Diversity and Population Health-Related Cardiovascular Outcomes Associated with Warfarin Use in Atrial Fibrillation: An Analysis Using Administrative Claims Data.

Anticoagulants are effective for stroke prevention in atrial fibrillation (AF). Data on population health-related cardiovascular outcomes by race/ethnicity and gender are not well described. The aim was to assess the impact of patient diversity on associated cardiovascular outcomes related to warfarin anticoagulation in Medicare beneficiaries with AF. Medicare administrative claims data for years 2000-2010 were used to calculate AF prevalence and rates of new AF cases. Three 20% sample cohorts of new AF beneficiaries for years 2000, 2005, and 2007 were extracted and analyzed in a longitudinal study design. The impact of warfarin on associated cardiovascular outcomes was measured with respect to race/ethnicity and gender. Measured outcomes included the risk of stroke, mortality and hospitalization after adjusting for age, gender, race/ethnicity, CHADS2 score and warfarin. AF prevalence and warfarin use increased while stroke and mortality rates declined across race/ethnicity and gender from 2000 to 2010. Analyses comparing Whites to non-Whites highlighted several disparities: (1) Blacks were 40% (p < 0.0001) more likely to have a stroke even after adjustment for warfarin; (2) in 2007, Hispanics had a 35% (p < 0.01) higher prevalence of stroke and warfarin did not reduce the risk; and (3) Asians had better outcomes. Warfarin reduced stroke less well in women who had a lower risk of death and hospitalization. Despite a > 70% (p < 0.0001) reduction in mortality for warfarin users, Blacks had a 25% (p < 0.0001) higher mortality risk than Whites. Differences in population health metrics across race/ethnicity and gender exist in AF. Across all metrics, Blacks had comparatively worse outcomes. Patient diversity should be a focus for future investigations in AF to improve outcomes in the whole population. National Minority Quality Forum.

Stroke, Major Bleeding, and Mortality Outcomes in Warfarin Users With Atrial Fibrillation and Chronic Kidney Disease: A Meta-Analysis of Observational Studies.

The use of warfarin in patients with atrial fibrillation (AF) and chronic kidney disease (CKD) can be problematic because of increased bleeding risk. We performed a systematic review and meta-analysis of observational studies that evaluated the use of warfarin in patients with AF and CKD to evaluate the risks of ischemic stroke/thromboembolism, major bleeding, and mortality. PUBMED, EMBASE, CINAHL, ProQuest, and Google Scholar databases were electronically searched through January 12, 2015. Additionally, a manual search was performed for relevant references. Random-effects model was used to estimate the pooled hazard ratio (HR) with 95% CI. CKD was divided into non-end-stage CKD and end-stage CKD (on renal replacement therapy) and separate analyses were performed. Thirteen publications from 11 cohorts (six retrospective and five prospective) including >48,500 total patients with >11,600 warfarin users were included in the meta-analysis. In patients with AF and non-end-stage CKD, warfarin resulted in a lower risk of ischemic stroke/thromboembolism (HR, 0.70; 95% CI, 0.54-0.89; P = .004) and mortality (HR, 0.65; 95% CI, 0.59-0.72; P < .00001), but had no effect on major bleeding (HR, 1.15; 95% CI, 0.88-1.49; P = .31). In patients with AF and end-stage CKD, warfarin had no effect on the risks of stroke (HR, 1.12; 95% CI, 0.69-1.82; P = .65) and mortality (HR, 0.96; 95% CI, 0.81-1.13; P = .60), but increased the risks of major bleeding (HR, 1.30; 95% CI, 1.08-1.56; P = .005). Based on this meta-analysis, the use of warfarin for AF may have an unfavorable risk/benefit ratio in patients with end-stage CKD but not in those with non-end-stage CKD.

Novel oral anticoagulants and stroke prevention in atrial fibrillation and chronic heart failure

Heart failure (HF) and atrial fibrillation (AF) frequently coexist and share a reciprocal relationship. The presence of AF increases the propensity to HF and can worsen its severity as well as escalating the risk of stroke. Despite the proven efficacy of vitamin K antagonists and warfarin for stroke prevention in AF, their use is beset by numerous problems. These include their slow onset and offset of action, unpredictability of response, the need for frequent coagulant monitoring and serious concerns around the increased risks of intracranial and major bleeding. Three recently approved novel anticoagulants (dabigatran, rivaroxaban and apixaban) are already challenging warfarin use in AF. They have a predictable therapeutic response and a wide therapeutic range and do not necessitate coagulation monitoring. In this article, the relationship between HF and AF and the mechanisms for their compounded stroke risk are reviewed. The evidence to support the use of these three NOACs amongst patients with AF and HF is further explored.

Atrial fibrillation and warfarin use in haemodialysis patients: An individualized holistic approach is important in stroke prevention

Incidence and prevalence of atrial fibrillation (AF) is higher in haemodialysis (HD) population than general population. AF is associated with higher morbidity and mortality than sinus rhythm in this population. The purpose of this review is to summarize all available evidence regarding use of warfarin in HD patients with AF for stroke prevention. The enormous heterogeneity of available studies does not allow pooling of the data in the form of meta-analysis or systematic review. Current evidence regarding use of warfarin for AF in terms of risk benefit ratio in this population is limited and conflicting. Randomized control trials evaluating the safety and efficacy of anticoagulation in this population by means of risk/benefit assessment tools are urgently needed. However, suitable HD patients with AF should be counselled on their likelihood of reduction of stroke risk and experiencing side-effects before initiating anticoagulant therapy. It is particularly important to incorporate the patient's preferences and willingness to trade off benefit and risk in stroke prevention. An individualized holistic approach optimizing all potential risk factors of bleeding and ischemic stroke in HD patients with AF is recommended.

Perceived or Actual Barriers to Warfarin Use in Atrial Fibrillation Based on Electronic Medical Records

Compared with usual practice, clinical trials often exclude patients with relative contraindications. A study of real-world warfarin use could help inform trials of new medications that could potentially replace warfarin. The objective of this study was to describe potential barriers to warfarin use among patients with atrial fibrillation. This was a retrospective study of electronic medical records (1998-2007) from an inner-city public hospital and affiliated primary care clinics and included adults aged 18 years or more with atrial fibrillation. Exclusions included mitral or aortic valve replacement, hyperthyroidism, or no clinical encounter within 1 year after first diagnosis. Warfarin exposure was defined by electronic pharmacy or physician order data or, in a second definition, international normalized ratio > 1.3. A history of potential barriers to warfarin was defined by International Classification of Diagnoses, 9th revision codes or electronic medical record "dictionary" terms. Among 3329 patients, CHADS2 scores were 0 (17%), 1 (26%), 2-6 (57%). Among 1276 patients with CHADS2 scores >0 who were prescribed warfarin, rates of potential barriers to warfarin were gastrointestinal or genitourinary hemorrhage (20%), alcohol abuse (16%), renal insufficiency (15%), predisposition to falls (8%), cirrhosis/hepatitis (5%), intracranial hemorrhage (1%), other hemorrhage (6%), and age 75 years or more (23%). Among 1475 patients with CHADS2 scores >0 who were not prescribed warfarin, these rates differed by not >3% except for predisposition to falls (16%) and age 75 years or more (43%). In real-world practice, many patients given warfarin have contraindications that would exclude them from clinical trials, and many patients apparently eligible for warfarin do not receive it.

Use of warfarin in long-term care: a systematic review.

BackgroundThe use of warfarin in older patients requires special consideration because of concerns with comorbidities, interacting medications, and the risk of bleeding. Several studies have suggested that warfarin may be underused or inconsistently prescribed in long-term care (LTC); no published systematic review has evaluated warfarin use for stroke prevention in this setting. This review was conducted to summarize the body of published original research regarding the use of warfarin in the LTC population.MethodsA systematic literature search of the PubMed, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library was conducted from January 1985 to August 2010 to identify studies that reported warfarin use in LTC. Studies were grouped by (1) rates of warfarin use and prescribing patterns, (2) association of resident and institutional characteristics with warfarin prescribing, (3) prescriber attitudes and concerns about warfarin use, (4) warfarin management and monitoring, and (5) warfarin-related adverse events. Summaries of study findings and quality assessments of each study were developed.ResultsTwenty-two studies met the inclusion criteria for this review. Atrial fibrillation (AF) was the most common indication for warfarin use in LTC and use of warfarin for stroke survivors was common. Rates of warfarin use in AF were low in 5 studies, ranging from 17% to 57%. These usage rates were low even among residents with high stroke risk and low bleeding risk. Scored bleeding risk had no apparent association with warfarin use in AF. In physician surveys, factors associated with not prescribing warfarin included risk of falls, dementia, short life expectancy, and history of bleeding. International normalized ratio was in the target range approximately half of the time. The combined overall rate of warfarin-related adverse events and potential events was 25.5 per 100 resident months on warfarin therapy.ConclusionsAmong residents with AF, use of warfarin and maintenance of INR levels to prevent stroke appear to be suboptimal. Among prescribers, perceived challenges associated with warfarin therapy often outweigh its benefits. Further research is needed to explicitly consider the appropriate balancing of risks and benefits in this frail patient population.

Predictors of warfarin use in atrial fibrillation in the United States: a systematic review and meta-analysis

BackgroundDespite warfarin's marked efficacy, not all eligible patients receive it for stroke prevention in AF. The aim of this meta-analysis was to evaluate the association between prescriber and/or patient characteristics and subsequent prescription of warfarin for stroke prevention in patients with atrial fibrillation (AF).MethodsObservational studies conducted in the US using multivariate analysis to determine the relationship between characteristics and the odds of receiving warfarin for stroke prevention were identified in MEDLINE, EMBASE and a manual review of references. Effect estimates of prescriber and/or patient characteristics from individual studies were pooled to calculate odds ratios (ORs) with 95% confidence intervals.ResultsTwenty-eight studies reporting results of 33 unique multivariate analyses were identified. Warfarin use across studies ranged from 9.1%-79.8% (median = 49.1%). There was a moderately-strong correlation between warfarin use and year of study (r = 0.60, p = 0.002). Upon meta-analysis, characteristics associated with a statistically significant increase in the odds of warfarin use included history of cerebrovascular accident (OR = 1.59), heart failure (OR = 1.36), and male gender (OR = 1.12). Those associated with a significant reduction in the odds of warfarin use included alcohol/drug abuse (OR = 0.62), perceived barriers to compliance (OR = 0.87), contraindication(s) to warfarin (OR = 0.81), dementia (OR = 0.32), falls (OR = 0.60), gastrointestinal hemorrhage (OR = 0.47), intracranial hemorrhage (OR = 0.39), hepatic (OR = 0.59), and renal impairment (OR = 0.69). While age per 10-year increase (OR = 0.78) and advancing age as a dichotomized variable (cut-off varied by study) (OR = 0.57) were associated with significant reductions in warfarin use; qualitative review of results of studies evaluating age as a categorical variable did not confirm this relationship.ConclusionsWarfarin use has increased somewhat over time. The decision to prescribe warfarin for stroke prevention in atrial fibrillation is based upon multiple prescriber and patient characteristics. These findings can be used by family practice prescribers and other healthcare decision-makers to target interventions or methods to improve utilization of warfarin when it is indicated for stroke prevention.

Abstract 2339: Predictors of Warfarin Use in Atrial Fibrillation in the United States

Introduction: Warfarin has been shown to be highly efficacious in preventing stroke in patients with atrial fibrillation (AF), yet it is still vastly underused for this purpose in the United States (US). Objective: To perform a meta-analysis to evaluate the association between prescriber and/or patient characteristics and subsequent prescription of warfarin for stroke prevention in patients with AF. Methods: Observational studies conducted only in the US using multivariate analysis to determine the relationship between prescriber and/or patient characteristics and the odds of receiving warfarin for stroke prevention in AF were identified from searches in the MEDLINE and EMBASE (1996-October 2010), as well as a manual review of references. Estimates of effect of prescriber and/or patient characteristics from individual studies were pooled to calculate summary odds ratios (ORs) with 95% confidence intervals (CIs) using a random-effects model. Results: Twenty-eight studies reporting the results of 33 unique multivariate analyses were identified. Warfarin use across included studies ranged from 9.1%-79.8%, with a median of 49.1%. There was a moderately strong correlation between increased warfarin use and time (r=0.60, p=0.002). Upon meta-analysis, characteristics associated with a statistically significant increase in the odds of warfarin use included history of cerebrovascular accident (OR=1.59, 95%CI 1.15-2.18), congestive heart failure (OR=1.36, 95%CI 1.18-1.57), and male gender (OR=1.12, 95%CI 1.04-1.21). Those associated with a statistically significant reduction in the odds of warfarin use included alcohol or drug abuse (OR=0.62, 95%CI 0.40-0.96), perceived barriers to compliance (OR=0.87, 95%CI 0.76-0.99), contraindication(s) to warfarin (OR=0.81, 95%CI 0.69-0.96), dementia (OR=0.32, 95%CI 0.14-0.75), falls (OR=0.60, 95%CI 0.43-0.85), gastrointestinal hemorrhage (OR=0.47, 95%CI 0.40-0.55), intracranial hemorrhage (OR=0.39, 95%CI 0.28-0.55), hepatic impairment (OR=0.59, 95%CI 0.50-0.70), renal impairment (OR=0.69, 95%CI 0.60-0.80), older compared to younger age (OR=0.57, 95%CI 0.39-0.82) and age per 10-year increase (OR=0.78, 95%CI 0.68-0.90). Conclusion: Warfarin use appears suboptimal, but has improved somewhat over time. Evidence suggests that the decision to prescribe warfarin for stroke prevention in patients with AF is based upon multiple prescriber and patient characteristics.

What are the barriers to warfarin use in atrial fibrillation?: Development of a questionnaire

Despite evidence of their benefit and efforts to increase usage, anticoagulation for stroke prophylaxis in atrial fibrillation (AF) patients remains underutilized. Previous surveys have assessed reasons for underuse of anticoagulation but have limitations including non-structured approach for eliciting barriers and use of clinical vignettes and not patient-level data. The objectives of this study were to develop a questionnaire to assess barriers to anticoagulation use for stroke prophylaxis in AF patients at a patient- and physician-level and to conduct a preliminary field-test of the instrument. Barriers to warfarin use were identified from a literature review, input from clinical experts, and a physician focus group. A sample of US physicians who treat AF patients completed the questionnaire. Physicians ranked their reluctance on a 1-10 scale (10 = very reluctant) in general to prescribe warfarin if a specific barrier was present in a patient and then indicated critical barriers to prescribing warfarin in a sample of their own AF patients not receiving warfarin. Forty-one barriers to warfarin use were identified and classified into 4 groups: patient medical characteristics (n = 17), health care system factors (n = 7), patient capability (n = 12), and patient preference (n = 5). Several new items were developed (e.g., difficulty in obtaining venous access), existing items were revised (e.g., timeframe for bleeding episodes subdivided into > or <or= 3 months), and multi-factorial barriers (e.g., dementia, epilepsy) were explored. The factor that most strongly influenced physicians' (n = 30) decisions not to prescribe warfarin was severe bleeding < 3 months ago (mean +/- SD: 9.2 +/- 1.3) while the most prevalent critical barriers to prescribing warfarin in specific AF patients (n = 24) was patient unwilling to undergo repeat testing (29%). This questionnaire has the potential to assist in better understanding barriers to warfarin use with a view to addressing and then overcoming warfarin underutilization. Preliminary data suggest patient preference and capabilities are at least as important as medical characteristics as barriers to prescribing warfarin in AF patients.

Effect of Access to Anticoagulation Management Services on Warfarin Use in Patients with Atrial Fibrillation

To determine the effect of access to ambulatory anticoagulation management services (AMS) on the rate of warfarin use in patients with atrial fibrillation. Retrospective medical record review. Two ambulatory care clinics in the same managed care system: one with and one without access to pharmacist-managed AMS. One hundred seventy-eight patients with atrial fibrillation diagnosed between June 2000 and June 2001. Warfarin use was assessed overall and by contraindications and risk factors for stroke. Independent predictors of therapy were identified. The overall rate of warfarin use in atrial fibrillation was higher in the clinic with access to AMS than in the clinic without access (77.9% vs 61.7%, p=0.03). In patients with no known contraindications, warfarin use increased by 20.2% with access to AMS versus no access (80.2% vs 60.0%, p=0.023). Patients aged 65 years or older with one or more risk factors for stroke and no contraindications were more likely to receive warfarin in the clinic with access to AMS than in the clinic without access (85.1% vs 53.8%, p=0.001). Access to AMS was an independent predictor of warfarin use (odds ratio 2.19, 95% confidence interval [CI] 1.05-4.56). Female sex was an independent negative predictor of warfarin use (odds ratio 0.48, 95% CI 0.24-0.96). In the managed care setting, use of warfarin for stroke prophylaxis in patients with atrial fibrillation was higher in the ambulatory care clinic with access to pharmacist-managed AMS than in the clinic without access.

Clinical Experience Supports Warfarin Use in Atrial Fibrillation

Many randomized clinical trials have demonstrated that anticoagulation with dose-adjusted warfarin is safe and effective for stroke prevention in patients with atrial fibrillation (AF), and multiple guideline statements recommend anticoagulation for most patients with AF. Nonetheless, anticoagulants are substantially underused in AF patients. One reason may be the concern that the ratio of benefits to risks conferred by warfarin therapy may not be as favorable in clinical practice as in clinical trials. To address this concern, researchers examined databases from a large managed care system in …

Predictors of warfarin use in atrial fibrillation: insights from the FRACTAL registry

Predictors of warfarin use in atrial fibrillation: insights from the FRACTAL registry

Frequency of anticoagulation for atrial fibrillation and reasons for its non-use at a veterans affairs medical center

Randomized clinical trials have led to guidelines for anticoagulation in atrial fibrillation (AF). However, it is unclear how successfully these guidelines are being implemented in clinical practice and there is concern that anticoagulation is underused. Therefore, we examined the rate of anticoagulation in 998 patients with AF who attended a Veterans Affairs Medical Center over a 2-year period. Warfarin was prescribed for 504 patients (51%) and not prescribed for 494 patients (49%). Of these 494 patients, 446 had sufficient data for further assessment. Warfarin was judged not indicated in 200 because AF was transient or lone. Warfarin was indicated in 246 patients, 63% having ≥3 risk factors for thromboembolism. However, 184 of these patients also had at least 1 contraindication to anticoagulation. Thus, warfarin was prescribed to 67% of patients with AF in whom anticoagulation was indicated and to 89% of such patients in whom it was indicated and who had no contraindications. However, 25% of AF patients with strong indications for anticoagulation had concomitant contraindications, which precluded its use. We conclude that the use of warfarin for AF in this setting is higher than previously reported and approaching ideal levels. However, there remains a large, problematic subgroup of patients with AF in whom indications for and contraindications to anticoagulation coexist.

Barriers to warfarin use in atrial fibrillation

Barriers to warfarin use in atrial fibrillation

Preventing ischemic stroke in patients with prior stroke and transient ischemic attack : a statement for healthcare professionals from the Stroke Council of the American Heart Association.

Stroke, the third leading cause of death in the United States, is a leading cause of adult neurological disability and accounts for the greatest number of hospitalizations for neurological disease. Although treatment of acute stroke has the potential of reducing death and disability, it is likely that prevention will more effectively reduce the ravages of stroke. The patient who is recovering from a mild stroke or who has had a recent transient ischemic attack (TIA) is at high risk of stroke recurrence, physical and intellectual disability, long-term institutionalization, and death. There is substantial evidence from observational epidemiological studies and clinical trials that recurrent ischemic stroke can be prevented (Table 1⇓). Control of risk factors is important for prevention of a first stroke and is practical after ischemic stroke and TIA have occurred. Identification of the specific ischemic stroke mechanism, eg, TIA or minor stroke ipsilateral to a moderate or severe internal carotid stenosis, guides decision making with regard to recurrent stroke prevention therapy (Table 2⇓). A patient with symptomatic cerebrovascular disease is likely to have other cardiovascular diseases or is predisposed to develop them. Preventive measures should complement reduction in risk of atherothrombotic events in the coronary arteries and other arterial territories. Certain nonmodifiable characteristics identify persons at high risk of stroke and stroke recurrence. These include advancing age, male sex, and black and Hispanic race-ethnic backgrounds. Some risk factors, however, such as elevated blood pressure, cigarette smoking, obesity, impaired glucose tolerance, and physical inactivity, are modifiable. Other conditions, ie, prior cardiovascular diseases such as coronary heart disease with angina or prior myocardial infarction, valvular heart disease, congestive heart failure, atrial fibrillation, increased left ventricular mass, and certain other echocardiographic abnormalities, identify persons at increased risk who may be treated with antithrombotic therapy. More recently, other modifiable risk …

Recent national patterns of warfarin use in atrial fibrillation.

Studies of selected populations suggest that anticoagulation in atrial fibrillation is underused and that nonclinical factors influence the use of this stroke-preventing therapy. We wished to examine recent national trends and predictors of warfarin sodium use in atrial fibrillation. A nationally representative sample of office visits from the 1989 to 1996 National Ambulatory Medical Care Surveys was used. We selected 1125 visits by patients with atrial fibrillation, including 877 visits to cardiologists and primary care physicians in which apparent contraindications for anticoagulation were absent. The principal outcome measure was the proportion of visits with warfarin reported. We analyzed trends in warfarin use and statistically evaluated the predictors of warfarin use. Warfarin use increased from 13% of atrial fibrillation visits in 1989 to 40% in 1993 (P for trend <.001) in patients without contraindications. Between 1993 and 1996, however, there was no change in warfarin use. Independent of other factors, warfarin was significantly more likely to be reported in patients with a history of stroke and in patients residing outside of the South. Warfarin use in atrial fibrillation has not increased recently, indicating inadequate implementation of this highly effective therapy. Barriers to anticoagulation in real-world clinical practice need to be identified and addressed.

Stroke Prevention in Non-Valvular Atrial Fibrillation

SummaryDespite evidence from 6 major clinical trials that warfarin effectively prevents strokes in atrial fibrillation, clinicians and health care managers may remain reluctant to support anticoagulant prophylaxis because of its perceived costs. Yet, doing nothing also has a price. To assess this, we carried out a pharmacoe-conomic analysis of warfarin use in atrial fibrillation. The course of the disease, including the occurrence of cerebral and systemic emboli, intracranial and other major bleeding events, was modeled and a meta-analysis of the clinical trials and other relevant literature was carried out to estimate the required probabilities with and without warfarin use. The cost of managing each event, including acute and subsequent care, home care equipment and MD costs, was derived by estimating the cost per resource unit, the proportion consuming each resource and the volume of use. Unit costs and volumes of use were determined from established US government databases, all charges were adjusted using cost-to-charge ratios, and a 3% discount rate was applied to costs incurred beyond the first year. The proportions of patients consuming each resource were estimated by fitting a joint distribution to the clinical trial data, stroke outcome data from a recent Swedish study and aggregate ICD-9 specific, Massachusetts discharge data. If nothing is done, 3.2% more patients will suffer serious emboli annually and the expected annual cost of managing a patient will increase by DM 2,544 (1996 German Marks), from DM 4,366 to DM 6,910. Extensive multiway sensitivity analyses revealed that the higher price of doing nothing persists except for very extreme combinations of inputs unsupported by literature or clinical standards. The price of doing nothing is thus so high, both in health and economic terms, that cost-consciousness as well as clinical considerations mandate warfarin prophylaxis in atrial fibrillation.

National Patterns of Warfarin Use in Atrial Fibrillation

Despite consensus that patients with atrial fibrillation benefit from warfarin sodium anticoagulation, little is known about national trends and predictors of anticoagulant use. We analyzed 1062 visits by patients with atrial fibrillation to randomly selected office-based physicians included in the National Ambulatory Medical Care Surveys in 1980, 1981, 1985, and 1989 through 1993. Warfarin and aspirin use in these patients was extrapolated to national patterns and logistic regression was used to determine independent predictors. Patients with atrial fibrillation made an estimated 1.3 (1980) to 3.1 (1992) million annual visits to physicians. Warfarin use in atrial fibrillation increased from 7% in 1980 and 1981 to 32% in 1992 and 1993 (P < .001 for trend). In 1992 and 1993, patients 80 years or older were significantly less likely to be taking warfarin (19%) compared with younger patients (36%), but showed similar rates of increase from 1980 and 1981 to 1992 and 1993. In 1992 and 1993, anticoagulation therapy was significantly more likely to be reported in visits to cardiologists (32%) and general internists (40%) compared with general and family practitioners (15%), but was similar in women (34%) and men (30%). Residents of the South (16%) had significantly lower rates of warfarin use than those in other regions of the United States (36%). Aspirin use increased from 3% to 10% (P = .001 for trend) and showed little overlap with warfarin use. Multiple logistic regression indicated that more recent year, residence outside the South, patient aged 65 to 74 years, and visits to cardiologists and internists increased the likelihood of warfarin use. Anticoagulant use for atrial fibrillation has increased dramatically. The substantial increase from 1989 and 1990 to 1992 and 1993 coincided with the publication of several randomized clinical trials reporting the benefits of warfarin. Although it is unrealistic to expect universal warfarin use, the 1992 and 1993 rate of 32% is probably suboptimal given the benefit of anticoagulation in preventing embolic strokes. The oldest patients, in whom warfarin may have its greatest benefit, appear to have the lowest rates of anticoagulant use.

National patterns of warfarin use in atrial fibrillation

National patterns of warfarin use in atrial fibrillation