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1.  Survey of the use of warfarin and the newer anticoagulant dabigatran in patients with atrial fibrillation 
Oral dabigatran was recently approved as an alternative to warfarin for prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. Unlike warfarin, dabigatran has a fixed dosage and few drug interactions, and does not require anticoagulation monitoring or dietary restrictions.
This study aimed to describe and compare characteristics of patients with atrial fibrillation who used dabigatran or only warfarin. Patients with a self-reported diagnosis of atrial fibrillation aged ≥18 years who were receiving (or had received) warfarin or dabigatran completed an online survey. Differences in characteristics of dabigatran and warfarin users were tested using chi-squared tests and analysis of variance for categorical and continuous variables, respectively.
Overall, 364 patients were surveyed (204 warfarin users, 160 dabigatran users). The mean age was 65.1 years, and 68.7% were male. Dabigatran users were more likely than warfarin users to be female (36.9% versus 27.0%) and to have experienced adverse events, including gastrointestinal bleeding, in the 3 months before the survey (21.9% versus 6.9%; P<0.05). Both groups reported high medication adherence (dabigatran users 0.65 versus warfarin users 0.63 missed doses/month). Dabigatran users were more likely than warfarin users to discuss treatment options with their physician before beginning therapy (36.9% versus 24.5%; P<0.05) and less likely to switch anticoagulant medication (10.7% versus 31.9%; P<0.05). Although dabigatran users were more likely to experience adverse events, they reported greater satisfaction with anticoagulation treatment than warfarin users.
The efficacy and convenience reported by dabigatran users resulted in greater treatment satisfaction among dabigatran users, even though adverse events decreased it. Treatment strategies that minimize adverse events may improve treatment satisfaction and adherence among patients with atrial fibrillation.
PMCID: PMC3923612  PMID: 24532967
atrial fibrillation; warfarin; dabigatran
2.  Nurses’ self-reported time estimation of anticoagulation therapy: a survey of warfarin management in long-term care 
BMC Nursing  2015;14:8.
A nursing shortage in the United States has resulted in increased workloads, potentially affecting the quality of care. This situation is particularly concerning in long-term care (LTC) facilities, where residents are older, frailer, and may be receiving multiple medications for comorbidities, thus requiring a greater commitment of nurse time. We conducted a survey of LTC nurses to determine how much of their time each week is spent managing newly started and stable warfarin-treated residents.
Forty LTC nurses validated the questionnaire to determine what protocols/procedures are involved in warfarin management. Twenty LTC nurses completed the survey, quantifying the time they spend on procedures related to warfarin management, and how often they performed each procedure for each resident each week.
The nurses reported that 26% of their residents were receiving warfarin; the majority (approximately 75%) of these residents began warfarin after admission to the facility. On average, the nurses spent 4.6 hours per week for treatment procedures and monitoring patients initiating warfarin therapy and 2.35 hours per week for each resident who was stable on warfarin therapy on admission. Overall, to care for an average number of newly initiated and stable warfarin patients in a medium-size LTC facility, staff nurses are estimated to spend 68 hours per week.
Study limitations include the potential for bias because of the small sample size, representativeness of the sample, and the possibility of inaccuracies in respondents’ self-reported time estimation of warfarin-related procedures.
In the context of a well-documented and expanding nursing shortage in the United States, the substantial use of time and resources necessary to initiate, monitor, and manage warfarin treatment in elderly LTC patients is of concern. Until the problem of understaffing is resolved, implementation of therapies that are simpler and require less nursing time—e.g. the use of new oral anticoagulants in the place of warfarin—may be a way to free up nursing time for other essential care tasks.
Electronic supplementary material
The online version of this article (doi:10.1186/s12912-015-0058-x) contains supplementary material, which is available to authorized users.
PMCID: PMC4336714
Anticoagulants; Long-term care; Nursing shortage; Quality of care; Warfarin management; Monitoring
3.  Out-of-range INR values and outcomes among new warfarin patients with non-valvular atrial fibrillation 
Background Although efficacious in stroke prevention in non-valvular atrial fibrillation, many warfarin patients are sub-optimally managed. Objective To evaluate the association of international normalized ratio control and clinical outcomes among new warfarin patients with non-valvular atrial fibrillation. Setting Adult non-valvular atrial fibrillation patients (≥18 years) initiating warfarin treatment were selected from the US Veterans Health Administration dataset between 10/2007 and 9/2012. Method Valid international normalized ratio values were examined from the warfarin initiation date through the earlier of the first clinical outcome, end of warfarin exposure or death. Each patient contributed multiple in-range and out-of-range time periods. Main outcome measure The relative risk ratios of clinical outcomes associated with international normalized ratio control were estimated. Results 34,346 patients were included for analysis. During the warfarin exposure period, the incidence of events per 100 person-years was highest when patients had international normalized ratio <2:13.66 for acute coronary syndrome; 10.30 for ischemic stroke; 2.93 for transient ischemic attack; 1.81 for systemic embolism; and 4.55 for major bleeding. Poisson regression confirmed that during periods with international normalized ratio <2, patients were at increased risk of developing acute coronary syndrome (relative risk ratio: 7.9; 95 % confidence interval 6.9–9.1), ischemic stroke (relative risk ratio: 7.6; 95 % confidence interval 6.5–8.9), transient ischemic attack (relative risk ratio: 8.2; 95 % confidence interval 6.1–11.2), systemic embolism (relative risk ratio: 6.3; 95 % confidence interval 4.4–8.9) and major bleeding (relative risk ratio: 2.6; 95 % confidence interval 2.2–3.0). During time periods with international normalized ratio >3, patients had significantly increased risk of major bleeding (relative risk ratio: 1.5; 95 % confidence interval 1.2–2.0). Conclusion In a Veterans Health Administration non-valvular atrial fibrillation population, exposure to out-of-range international normalized ratio values was associated with significantly increased risk of adverse clinical outcomes.
PMCID: PMC4312387  PMID: 25428444
Atrial fibrillation; Clinical outcomes; International normalized ratio; USA; US veterans; Warfarin
4.  The Economic Burden to Medicare of Stroke Events in Atrial Fibrillation Populations With and Without Thromboprophylaxis 
Population Health Management  2014;17(3):159-165.
Some 3 million people in the United States have atrial fibrillation (AF). Without thromboprophylaxis, AF increases overall stroke risk 5-fold. Prevention is paramount as AF-related strokes tend to be severe. Thromboprophylaxis reduces the annual incidence of stroke in AF patients by 22%–62%. However, antithrombotics are prescribed for only about half of appropriate AF patients. The study team estimates the economic implications for Medicare of fewer stroke events resulting from increased thromboprophylaxis among moderate- to high-risk AF patients. The decision model used considers both reduced stroke and increased bleeding risk from thromboprophylaxis for a hypothetical cohort on no thromboprophylaxis (45%), antiplatelets (10%), and anticoagulation (45%). AF prevalence, stroke risk, and stroke risk reduction are adjusted for age, comorbidities, and anticoagulation/antiplatelet status. Health care costs are literature based. At baseline, an estimated 24,677 ischemic strokes, 9127 hemorrhagic strokes, and 9550 bleeding events generate approximately $2.63 billion in annual event-related health care costs to Medicare for every million AF patients eligible for thromboprophylaxis. A 10% increase in anticoagulant use in the untreated population would reduce stroke events by 9%, reduce stroke fatalities by 9%, increase bleed events by 5%, and reduce annual stroke/bleed-related costs to Medicare by about $187 million (7.1%) for every million eligible AF patients. A modest 10% increase in the use of thromboprophylaxis would reduce event-related costs to Medicare by 7.1%, suggesting a compelling economic motivation to improve rates of appropriate thromboprophylaxis. New oral anticoagulants offering better balance between the risks of stroke and major bleeding events may improve these clinical and economic outcomes. (Population Health Management 2014;17:159–165)
PMCID: PMC4050709  PMID: 24476557
5.  Impact of Once-Daily Versus Twice-Daily Dosing Frequency on Adherence to Chronic Medications among Patients with Venous Thromboembolism 
The Patient  2013;6(3):213-224.
Multiple daily dosing may be negatively associated with patient medication adherence; however, adherence-related data are lacking in a patient population with venous thromboembolism (VTE).
To assess the adherence rates between once-daily (OD) and twice-daily (BID) dosing regimens of chronic medications in patients with VTE.
We analyzed the PharMetrics Integrated Claims database (claims of commercial insurers in the US) from 1 January 2004, through 31 December 2009. Adult patients with continuous insurance coverage, newly initiated on diabetes mellitus or hypertension medication, and having at least one VTE diagnosis were included. Adherence to OD and BID therapies was calculated by using two measures: medication possession ratio (MPR) and proportion of days covered (PDC). Adherence was defined as an MPR or PDC ≥0.8. Multivariate logistic regressions were conducted to compare the probability of adherence between the OD and BID groups adjusting for baseline confounders.
A total of 4,867 OD and 1,069 BID patients were identified. Mean duration of exposure to therapy for OD and BID patients was 386 and 356 days (p = 0.011), respectively. Based on MPR, 69 % of OD and 62 % of BID patients were adherent (p < 0.001). For PDC at 12 months, the proportion of adherent patients for the OD and BID groups was 45 and 36 % (p < 0.001), respectively. Adjusted odds ratios (95 % CI) of adherence for the OD relative to BID group were 1.61 (1.37–1.89) based on MPR (p < 0.001) and 1.46 (1.16–1.83) based on PDC at 12 months (p = 0.001).
This study demonstrates that VTE patients treated with chronic medications on OD dosing regimens were associated with an approximately 39–61 % higher likelihood of adherence compared with subjects on BID dosing regimens.
Electronic supplementary material
The online version of this article (doi:10.1007/s40271-013-0020-5) contains supplementary material, which is available to authorized users.
PMCID: PMC3751276  PMID: 23857628
6.  Warfarin for Prevention of Thrombosis Among Long-Term Care Residents with Atrial Fibrillation: Evidence of Continuing Low Use Despite Consideration of Stroke and Bleeding Risk 
Drugs & Aging  2013;30(6):417-428.
The aims of the study were to evaluate usage rates of warfarin in stroke prophylaxis and the association with assessed stages of stroke and bleeding risk in long-term care (LTC) residents with atrial fibrillation (AFib).
A cross-sectional analysis of two LTC databases (the National Nursing Home Survey [NNHS] 2004 and an integrated LTC database: AnalytiCare) was conducted. The study involved LTC facilities across the USA (NNHS) and within 19 states (AnalytiCare). It included LTC residents diagnosed with AFib (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] diagnostic code 427.3X). Consensus guideline algorithms were used to classify residents by stroke risk categories: low (none or 1+ weak stroke risk factors), moderate (1 moderate), high (2+ moderate or 1+ high). Residents were also classified by number of risk factors for bleeding (0–1, 2, 3, 4+). Current use of warfarin was assessed. A logistic regression model predicted odds of warfarin use associated with the stroke and bleeding risk categories.
The NNHS and AnalytiCare databases had 1,454 and 3,757 residents with AFib, respectively. In all, 34 % and 45 % of residents with AFib in each respective database were receiving warfarin. Only 36 % and 45 % of high-stroke-risk residents were receiving warfarin, respectively. In the logistic regression model for the NNHS data, when compared with those residents having none or 1+ weak stroke risk and 0–1 bleeding risk factors, the odds of receiving warfarin increased with stroke risk (odds ratio [OR] = 1.93, p = 0.118 [1 moderate risk factor]; OR = 3.19, p = 0.005 [2+ moderate risk factors]; and OR = 8.18, p ≤ 0.001 [1+ high risk factors]) and decreased with bleeding risk (OR = 0.83, p = 0.366 [2 risk factors]; OR = 0.47, p ≤ 0.001 [3 risk factors]; OR = 0.17, p ≤ 0.001 [4+ risk factors]). A similar directional but more constrained trend was noted for the AnalytiCare data: only 3 and 4+ bleeding risk factors were significant.
The results from two LTC databases suggest that residents with AFib have a high risk of stroke. Warfarin use increased with greater stroke risk and declined with greater bleeding risk; however, only half of those classified as appropriate warfarin candidates were receiving guideline-recommended anticoagulant prophylaxis.
PMCID: PMC3663250  PMID: 23456440
7.  Anticoagulant Use for Prevention of Stroke in a Commercial Population with Atrial Fibrillation 
American Health & Drug Benefits  2012;5(5):291-298.
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, and patients with AF are at an increased risk for stroke. Thromboprophylaxis with vitamin K antagonists reduces the annual incidence of stroke by approximately 60%, but appropriate thromboprophylaxis is prescribed for only approximately 50% of eligible patients. Health plans may help to improve quality of care for patients with AF by analyzing claims data for care improvement opportunities.
To analyze pharmacy and medical claims data from a large integrated commercial database to determine the risk for stroke and the appropriateness of anticoagulant use based on guideline recommendations for patients with AF.
This descriptive, retrospective claims data analysis used the Anticoagulant Quality Improvement Analyzer software, which was designed to analyze health plan data. The data for this study were obtained from a 10% randomly selected sample from the PharMetrics Integrated Database. This 10% sample resulted in almost 26,000 patients with AF who met the inclusion criteria for this study. Patients with a new or existing diagnosis of AF between July 2008 and June 2010 who were aged ≥18 years were included in this analysis. The follow-up period was 1 year. Demographics, stroke risk level (CHADS2 and CHA2DS2-VASc scores), anticoagulant use, and inpatient stroke hospitalizations were analyzed through the analyzer software.
Of the 25,710 patients with AF (CHADS2 score 0–6) who were eligible to be included in this study, 9093 (35%) received vitamin K antagonists and 16,617 (65%) did not receive any anticoagulant. Of the patients at high risk for stroke, as predicted by CHADS2, 39% received an anticoagulant medication. The rates of patients receiving anticoagulant medication varied by age-group—16% of patients aged <65 years, 22% of those aged 65 to 74 years, and 61% of elderly ≥75 years. Among patients hospitalized for stroke, only 28% were treated with an anticoagulant agent in the outpatient setting before admission.
Our findings support the current literature, indicating that many patients with AF are not receiving appropriate thromboprophylaxis to counter their risk for stroke. Increased use of appropriate anticoagulation, particularly in high-risk patients, has the potential to reduce the incidence of stroke along with associated fatalities and morbidities.
PMCID: PMC4046452  PMID: 24991327
8.  Use of warfarin in long-term care: a systematic review 
BMC Geriatrics  2012;12:14.
The 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.
A 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.
Twenty-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.
Among 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.
PMCID: PMC3364846  PMID: 22480376
9.  Laboratory Safety Monitoring of Chronic Medications in Ambulatory Care Settings 
To evaluate laboratory safety monitoring in patients taking selected chronic prescription drugs.
Retrospective study using 1999–2001 claims data to calculate rates of missed laboratory tests (potential laboratory monitoring errors). Eleven drugs/drug groups and 64 laboratory tests were evaluated.
Two staff/network model health maintenance organizations.
Continuously enrolled health plan members age≥19 years taking ≥1 chronic medications.
Among patients taking chronic medications (N=29,823 in 1999, N=32,423 in 2000, and N=36,811 in 2001), 47.1% in 1999, 45.0% in 2000, and 44.0% in 2001 did not receive ≥1 test recommended for safety monitoring. Taking into account that patients were sometimes missing more than 1 test for a given drug and that patients were frequently taking multiple drugs, the rate of all potential laboratory monitoring errors was 849/1,000 patients/year in 1999, 810/1,000 patients/year in 2000, and 797/1,000 patients/year in 2001. Rates of potential laboratory monitoring errors varied considerably across individual drugs and laboratory tests.
Lapses in laboratory monitoring of patients taking selected chronic medications were common. Further research is needed to determine whether, and to what extent, this failure to monitor patients is associated with adverse clinical outcomes.
PMCID: PMC1490088  PMID: 15857489
patient safety; laboratory testing; chronic medications; medical errors; medication safety

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