BACKGROUND: have an increased risk for adverse cardiovascular events. In 2010, the US Food and Drug Administration issued a boxed warning cautioning against the use of clopidogrel in such patients. We sought to assess the impact of CYP2C19 genetic testing on prescribing patterns for antiplatelet therapy among patients with acute coronary syndrome or percutaneous coronary intervention. METHODS AND RESULTS: testing. Genotype and phenotype results were provided to patients and their physicians, but no specific treatment recommendations were suggested. Patients were categorized based on their genotype (carriers versus noncarriers) and phenotype (extensive, intermediate, and poor metabolizers). The primary outcome was intensification in antiplatelet therapy defined as either dose escalation of clopidogrel or replacement of clopidogrel with prasugrel. Between July 2010 and April 2012, 6032 patients were identified, and 499 (8.3%) underwent CYP2C19 genotyping, of whom 146 (30%) were found to have >/=1 reduced function allele, including 15 (3%) with 2 reduced function alleles. Although reduced function allele carriers were significantly more likely than noncarriers to have an intensification of their antiplatelet therapy, only 20% of poor metabolizers of clopidogrel had their antiplatelet therapy intensified. CONCLUSIONS: allele carriers, but only 20% of poor metabolizers of clopidogrel had an escalation in the dose of clopidogrel or were switched to prasugrel. These prescribing patterns likely reflect the unclear impact and evolving evidence for clopidogrel pharmacogenomics.
BACKGROUND: New anticoagulants may improve health outcomes in patients with atrial fibrillation, but it is unclear whether their use is cost-effective.METHODS AND RESULTS: A Markov state transition was created to compare 4 therapies: dabigatran 150 mg BID, apixaban 5 mg BID, rivaroxaban 20 mg QD, and warfarin therapy. The population included those with newly diagnosed atrial fibrillation who were eligible for treatment with warfarin. Compared with warfarin, apixaban, rivaroxaban, and dabigatran, costs were $93 063, $111 465, and $140 557 per additional quality-adjusted life year gained, respectively. At a threshold of $100 000 per quality-adjusted life year, apixaban provided the greatest absolute benefit while still being cost-effective, although warfarin would be superior if apixaban was 2% less effective than expected. Although apixaban was the optimal strategy in our base case, in probabilistic sensitivity analysis, warfarin was optimal in an equal number of iterations at a cost-effectiveness threshold of $100 000 per quality-adjusted life year.CONCLUSTIONS: While at a standard cost-effectiveness threshold of $100 000 per quality-adjusted life year, apixaban seems to be the optimal anticoagulation strategy; this finding is sensitive to assumptions about its efficacy and cost. In sensitivity analysis, warfarin seems to be the optimal choice in an equal number of simulations. As a result, although all the novel oral anticoagulants produce greater quality-adjusted life expectancy than warfarin, they may not represent good value for money.
BACKGROUND: Eliminating out-of-pocket costs for patients after myocardial infarction (MI) improves adherence to preventive therapies and reduces clinical events. Because adherence to medical therapy is low among patients treated with coronary artery bypass graft surgery (CABG), we evaluated the impact of providing full prescription coverage to this patient subgroup. METHODS AND RESULTS: The MI Free Rx Event and Economic Evaluation (FREEE) trial randomly assigned 5855 patients with MI to full prescription coverage or usual formulary coverage for all statins, beta-blockers, angiotensin-converting enzyme inhibitors, or angiotensin receptor blockers. We assessed the impact of full prescription coverage on adherence, clinical outcomes, and healthcare costs using adjusted models among the 1052 patients who underwent CABG at the index hospitalization and 4803 who did not. CABG patients were older and had more comorbid illness (P<0.01). After MI, CABG patients were significantly more likely to receive beta-blockers and statins but were less likely to receive angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy (P<0.01). Receiving full drug coverage increased rates of adherence to all preventative medications after CABG (all P<0.05). Full coverage was also associated with nonsignificant reductions in the rate of major vascular events or revascularization for patients treated with CABG (hazard ratio, 0.91; 95% confidence interval, 0.66-1.25) or without CABG (hazard ratio, 0.93; 95% confidence interval, 0.82-1.06), with no interaction noted (Pint=NS). After CABG, full prescription coverage significantly reduced patient out-of-pocket spending for drugs (P=0.001) without increasing overall health expenditures (P=NS). CONCLUSIONS: Eliminating drug copayments after MI provides consistent benefits to patients treated with or without CABG, leading to increased medication adherence, trends toward improved clinical outcomes, and reduced patient out-of-pocket expenses.
OBJECTIVE: To examine the relation between the type of stress ulcer prophylaxis administered and the risk of postoperative pneumonia in patients undergoing coronary artery bypass grafting. DESIGN: Retrospective cohort study. SETTING: Premier Research Database. PARTICIPANTS: 21,214 patients undergoing coronary artery bypass graft surgery between 2004 and 2010; 9830 (46.3%) started proton pump inhibitors and 11,384 (53.7%) started H2 receptor antagonists in the immediate postoperative period. MAIN OUTCOME MEASURE: Occurrence of postoperative pneumonia, assessed using appropriate diagnostic codes. RESULTS: Overall, 492 (5.0%) of the 9830 patients receiving a proton pump inhibitor and 487 (4.3%) of the 11,384 patients receiving an H2 receptor antagonist developed postoperative pneumonia during the index hospital admission. After propensity score adjustment, an elevated risk of pneumonia associated with treatment with proton pump inhibitors compared with H2 receptor antagonists remained (relative risk 1.19, 95% confidence interval 1.03 to 1.38). In the instrumental variable analysis, use of a proton pump inhibitor (compared with an H2 receptor antagonist) was associated with an increased risk of pneumonia of 8.2 (95% confidence interval 0.5 to 15.9) cases per 1000 patients. CONCLUSIONS: Patients treated with proton pump inhibitors for stress ulcer had a small increase in the risk of postoperative pneumonia compared with patients treated with H2 receptor antagonists; this risk remained after confounding was accounted for using multiple analytic approaches.
OBJECTIVE: The incidence of hospital-acquired Clostridium difficile infection (CDI) has increased rapidly over the past decade; patients undergoing major surgery, including coronary artery bypass grafting (CABG), are at particular risk. Intravenous vancomycin exposure has been identified as an independent risk factor for CDI, but this is controversial. It is not known whether vancomycin administered for surgical site infection prophylaxis increases the risk of CDI. METHODS: Using data from the Premier Perspective Comparative Database, we assembled a cohort of 69,807 patients undergoing CABG surgery between 2004 and 2010 who received either a cephalosporin alone (65.1%) or a cephalosporin plus vancomycin (34.9%) on the day of surgery. Patients were observed for CDI until discharge from the index hospitalization. In these groups, we evaluated the comparative rate of postoperative CDI with Cox models; confounding was addressed using propensity scores. RESULTS: In all, 77 (0.32%) of the 24,393 patients receiving a cephalosporin plus vancomycin and 179 (0.39%) of the 45,414 patients receiving a cephalosporin alone had postoperative CDI (unadjusted hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.56-0.95). After adjusting for confounding variables with either propensity score matching or stratification, there was no meaningful association between adjuvant vancomycin exposure and postoperative CDI (HR, 0.85; 95% CI, 0.61-1.19; and HR, 0.85; 95% CI, 0.63-1.15, respectively). Results of multiple sensitivity analyses were similar to the main findings. CONCLUSIONS: After adjustment for patient and surgical characteristics, a short course of prophylactic vancomycin was not associated with an increased risk of CDI among patients undergoing CABG surgery.
BACKGROUND: Rates of nonadherence to aromatase inhibitors (AIs) among Medicare beneficiaries with hormone receptor-positive early breast cancer are high. Out-of-pocket drug costs appear to be an important contributor to this and may be addressed by eliminating copayments and other forms of patient cost sharing. The authors estimated the incremental cost-effectiveness of providing Medicare beneficiaries with full prescription coverage for AIs compared with usual prescription coverage under the Medicare Part D program. METHODS: A Markov state-transition model was developed to simulate AI use and disease progression in a hypothetical cohort of postmenopausal Medicare beneficiaries with hormone receptor-positive early breast cancer. The analysis was conducted from the societal perspective and considered a lifetime horizon. The main outcome was an incremental cost-effectiveness ratio, which was measured as the cost per quality-adjusted life-year (QALY) gained. RESULTS: For patients receiving usual prescription coverage, average quality-adjusted survival was 11.35 QALYs, and lifetime costs were $83,002. For patients receiving full prescription coverage, average quality-adjusted survival was 11.38 QALYs, and lifetime costs were $82,728. Compared with usual prescription coverage, full prescription coverage would result in greater quality-adjusted survival (0.03 QALYs) and less resource use ($275) per beneficiary. From the perspective of Medicare, full prescription coverage was cost-effective (incremental cost-effectiveness ratio, $15,128 per QALY gained) but not cost saving. CONCLUSIONS: Providing full prescription coverage for AIs to Medicare beneficiaries with hormone receptor-positive early breast cancer would both improve health outcomes and save money from the societal perspective.
BACKGROUND: Significant disparities exist in cardiovascular outcomes based on race/ethnicity and gender. Rates of evidence-based medication use and long-term medication adherence also appear to be lower in racial subgroups and women but have been subject to little attention. Our objective was to evaluate the effect of race/ethnicity and gender on adherence to statin therapy for primary or secondary prevention. METHODS AND RESULTS: Studies were identified through a systematic search of MEDLINE, EMBASE, ClinicalTrials.gov, and the Cochrane Database of Systematic Reviews (through April 1, 2010) and manual examination of references in selected articles. Studies reporting on adherence to statins by men and women or patients of white and nonwhite race were included. Information on study design, adherence measurement, duration, geographic location, sample size, and patient demographics was extracted using a standardized protocol. From 3,022 potentially relevant publications, 53 studies were included. Compared with men, women had a 10% greater odds of nonadherence (odds ratio 1.10, 95% confidence interval [CI], 1.07-1.13). Nonwhite race patients had a 53% greater odds of nonadherence than white race patients (odds ratio 1.53, 95% CI 1.25-1.87). There was significant heterogeneity in the pooled estimate for gender (I(2) 0.95, P value for heterogeneity <.001) and race (I(2) 0.98, P value for heterogeneity <.001). The overall results remained unchanged in those subgroups that had significantly less heterogeneity. CONCLUSIONS: Among patients prescribed statins, women and nonwhite patients are at increased risk for nonadherence. Further research is needed to identify interventions best suited to improve adherence in these populations.
BACKGROUND: Classifying medication adherence is important for efficiently targeting adherence improvement interventions. The purpose of this study was to evaluate the use of a novel method, group-based trajectory models, for classifying patients by their long-term adherence. RESEARCH DESIGN: We identified patients who initiated a statin between June 1, 2006 and May 30, 2007 in prescription claims from CVS Caremark and evaluated adherence over the subsequent 15 months. We compared several adherence summary measures, including proportion of days covered (PDC) and trajectory models with 2-6 groups, with the observed adherence pattern, defined by monthly indicators of full adherence (defined as having >/=24 d covered of 30). We also compared the accuracy of adherence prediction based on patient characteristics when adherence was defined by either a trajectory model or PDC. RESULTS: In 264,789 statin initiators, the 6-group trajectory model summarized long-term adherence best (C=0.938), whereas PDC summarized less well (C=0.881). The accuracy of adherence predictions was similar whether adherence was classified by PDC or by trajectory model. CONCLUSIONS: Trajectory models summarized adherence patterns better than traditional approaches and were similarly predicted by covariates. Group-based trajectory models may facilitate targeting of interventions and may be useful to adjust for confounding by health-seeking behavior.
BACKGROUND: The need to identify how best to structure health insurance and to deliver health care services is a central priority for comparative effectiveness research. Studies designed to evaluate these issues are frequently conducted in large insurance systems. We sought to describe the challenges faced when conducting trials in this context. METHODS: Using the Post-Myocardial Infarction Free Rx Event and Economic Evaluation (MI FREEE) trial as an example, we describe the methodological and practical challenges of conducting trials in large insurance systems. RESULTS: We encountered six key challenges while conducting MI FREEE trial, namely the need to obtain plan sponsor permission to experiment, the desire of plan sponsors to have all of their beneficiaries receive the same intervention, the inaccuracy of claims-based identification methods and the impact of claims lag on the timely enrollment of potentially eligible patients, the reluctance of patients to participate in insurance-based interventions and the potential need for informed consent, the frequent introduction of new cointerventions in real-world delivery systems, and the high rates of loss to follow-up because of insurance "churn." We describe the approaches we used to overcome these challenges. CONCLUSIONS: Studies in insurance settings are a powerful and necessary design for evaluating comparative effectiveness interventions. There are numerous strategies to address the potential logistical and methodological challenges that this research environment uniquely creates.
OBJECTIVES: To ascertain predictors of initiation of brand-name versus generic narrow therapeutic index (NTI) drugs. DESIGN: Retrospective cohort study. SETTING: Data from CVS Caremark were linked to Medicare claims and to U.S. census data. PARTICIPANTS: Individuals aged 65 and older who initiated an NTI drug in 2006 and 2007 (N = 36,832). MEASUREMENTS: Demographic, health service utilization, and geographic predictors of whether participants initiated a generic or brand-name version of their NTI drug were identified using logistic regression. RESULTS: Overall, 30,014 (81.5%) participants started on a generic version of their NTI drug. The most commonly initiated NTI drugs were warfarin (n = 17,790; 48%), levothyroxine (n = 10,779; 29%), and digoxin (n = 6,414; 17%). Older age (odds ratio (OR) = 1.12, 95% confidence interval (CI) = 1.02-1.22 comparing aged >/=85 with 65-74), higher burden of comorbidity (OR = 1.05, 95% CI = 1.04-1.07 for each 1-point increase in comorbidity score), and prior use of any generic drug (OR = 1.55, 95% CI = 1.29-1.87) were positively associated with generic drug initiation. Independent of other predictors, residing in the census block group with the highest generic use was positively associated with greater odds of generic NTI drug initiation (OR = 1.24, 95% CI = 1.14-1.35 compared with the lowest quintile). CONCLUSION: Demographic, health service utilization, and geographic characteristics are important determinants of whether individuals initiate treatment with a brand-name or generic NTI drug. These factors may contribute to disparities in care and highlight potential targets for educational campaigns.
OBJECTIVES: To better understand the impact of retail clinic use on a patient's annual total cost of care. STUDY DESIGN: A propensity score matched-pair, cohort design was used to analyze healthcare spending patterns among CVS Caremark employees in the year following a visit to a MinuteClinic, the retail clinics inside CVS pharmacies. METHODS: De-identified medical and pharmacy claims for CVS Caremark employees and their dependents who received care at a retail clinic between June 1, 2009, and May 31, 2010, were matched to those of subjects who received care elsewhere. High-dimensional propensity score and greedy matching techniques were used to create a 1-to-1 matched cohort that was analyzed using generalized linear regression models. RESULTS: Individuals using a retail clinic had a lower total cost of care (-$262; 95% confidence interval, -$510 to -$31; P = .025) in the year following their clinic visit than individuals who received care in other settings. This savings was primarily due to lower medical expenses at physicians' offices ($77 savings, P = .008) and hospital inpatient care ($121 savings, P = .049). The 6022 retail clinic users also had 142 (12%) fewer emergency department visits (P = .01), though this was not related to significant cost savings. CONCLUSIONS: This study found that retail clinic use was associated with lower overall total cost of care compared with that at alternative sites. Savings may extend beyond the retail clinic visit itself to other types of medical utilization.
Value-based insurance design (VBID) is an approach that attempts to improve the quality of care by selectively encouraging or discouraging the use of specific health care services, based on their potential benefit to patients' health, relative to their cost. Lowering beneficiary cost sharing or out-of-pocket spending to increase medication adherence is one common element of value-based insurance design. We conducted a systematic review of the peer-reviewed literature to evaluate the evidence of the effects of VBID policies on medication adherence and medical expenditures. We identified thirteen studies assessing the effects of VBID programs and found that the programs were consistently associated with improved adherence (average change of 3.0 percent over one year), as well as with lower out-of-pocket spending for drugs. In the studies we reviewed, providing more generous coverage did not lead to significant changes in overall medical spending for patients and insurers. Further research is needed to understand how best to structure VBID programs to both improve quality and reduce spending.
BACKGROUND: Given the huge burden of coronary artery disease and the effectiveness of medication therapy, understanding and quantifying known impacts of poor medication adherence for primary and secondary prevention is crucial. We sought to systematically review the literature on this topic area with a focus on quantified cost and clinical outcomes related to adherence. METHODS: We conducted a systematic review of the literature between 1966 and November 2011 using a fixed search strategy, multiple reviewers, and a quality rating scale. We found 2636 articles using this strategy, eventually weaning them down to 25 studies that met our inclusion criteria. Three reviewers independently reviewed the studies and scored them for quality using the Newcastle Ottawa Scoring Scale. RESULTS: We found 5 studies (4 of which focused on statins) that measured the impact of medication adherence on primary prevention of coronary artery disease and 20 articles that focused on the relationship between medication adherence to costs and outcomes related to secondary prevention of coronary artery disease. Most of these latter studies focused on antihypertensive medications and aspirin. All controlled for confounding comorbidities and sociodemographic characteristics, but few controlled for likelihood of adherent patients to have healthier behaviors ("healthy adherer effect"). Three studies found that high adherence significantly improves health outcomes and reduces annual costs for secondary prevention of coronary artery disease (between $294 and $868 per patient, equating to 10.1%-17.8% cost reductions between high- and low-adherence groups). The studies were all of generally of high quality on the Newcastle Ottawa Scale (median score 8 of 9). CONCLUSIONS: Increased medication adherence is associated with improved outcomes and reduced costs, but most studies do not control for a "healthy adherer" effect.
BACKGROUND: Generic prescription drugs are bioequivalent to brand-name versions but may not have consistent color or shape, which can cause confusion and lead to interruptions in medication use. We sought to determine whether switching among different-appearing antiepileptic drugs (AEDs) is associated with increased rates of medication nonpersistence, which can have serious medical, financial, and social consequences. METHODS: We designed a nested case-control study of commercially insured patients in the United States who initiated an AED. Cases were patients who became nonpersistent, defined as failure to fill a prescription within 5 days of the elapsed days supplied. Controls had no delay in refilling and were matched by sex, age, number of refills, and the presence of a seizure disorder diagnosis. We evaluated the 2 refills preceding nonpersistence and determined whether pill color and/or shape matched (“concordant”) or did not match (“discordant”). We compared the odds of discordance among cases and controls using multivariate conditional logistic regression, adjusting for baseline characteristics, and drug type. We repeated our analysis among patients with a seizure diagnosis. RESULTS: The AEDs dispensed had 37 colors and 4 shapes. A total of 11 472 patients with nonpersistence were linked to 50 050 controls. Color discordance preceded 136 cases (1.20%) but only 480 controls (0.97%) (adjusted odds ratio [OR], 1.27 [95% CI, 1.04-1.55]). Shape discordance preceded 18 cases (0.16%) and 54 controls (0.11%) (OR, 1.47 [95% CI, 0.85-2.54]). Within the seizure disorder diagnosis subgroup, the risk of nonpersistence after changes in pill color was also significantly elevated (OR, 1.53 [95%, CI 1.07-2.18]). CONCLUSIONS: Changes in pill color significantly increase the odds of nonpersistence; this may have important clinical implications. Our study supports a reconsideration of current regulatory policy that permits wide variation in the appearance of bioequivalent drugs.
Non-adherence to evidence-based medications is a major public health problem. Less than 50 % of patients with coronary artery disease adhere to their prescribed therapies and this has important implications for morbidity, mortality, and health care spending. Like most complex behaviors, medication non-adherence is not solely the result of poor patient choices. Rather, there are myriad potential contributors attributable to patients, health care providers, and, more broadly, the health care system. Interventions including patient education and behavioral modification, improving patient-physician communication, and eliminating copayments for preventive pharmacotherapy have all been studied. Clinicians play a critical role in helping improve adherence and assessment of adherence must become a standard component of each clinical encounter. Ultimately, given the various etiologies that contribute to non-adherence, achieving meaningful gains will undoubtedly require payors, providers, and policymakers to develop, rigorously evaluate, and systematically deploy strategies that address key patient, clinician, and health system factors.
PURPOSE: Treatment guidelines recommend insulin progression (switching from basal to a premixed insulin regimen, adding bolus doses, and/or increasing dosing frequency) to achieve A1C targets as type 2 diabetes progresses, but fewer patients are being progressed than would be indicated based on their disease status. This systematic review proposes 2 questions regarding insulin progression among patients with type 2 diabetes: (1) What are the patient, provider, and health system barriers to insulin progression? (2) Do insulin progression barriers differ between insulin-naive and insulin-experienced patients? METHODS: We conducted a systematic review in the MEDLINE, EMBASE, Science Citation Index, PsycINFO, CINAHL, and Cochrane Library databases through July 2011.RESULTS: Of 745 potentially relevant articles, 10 met inclusion criteria: 7 evaluated patient and 2 evaluated provider barriers, and 1 was an intervention to reduce barriers among physicians. Patients with prior insulin experience had fewer barriers arising from injection-related concerns and worries about the burden of insulin progression than did insulin-naive patients. Physician barriers included concerns about patients' ability to follow more complicated regimens as well as physicians' own inexperience with insulin and progression algorithms. The cross- sectional nature, narrow scope, and failure of all studies to examine patient, provider, and health systems barriers concurrently limited both barrier identification and an assessment of their impact on progression.CONCLUSIONS: Patient and physician experience with insulin and diabetes/insulin education were associated with fewer perceived barriers to insulin progression. Future studies should use multilevel longitudinal designs to quantify the relative impact of potential patient, provider, and health system factors on progression and health outcomes.
HMG-CoA reductase inhibitors, commonly known as statins, are some of the most widely prescribed medications worldwide and have been shown to be effective at lowering cholesterol in numerous long-term prospective trials, yet there are significant limitations to their use. First, patients receiving statin therapy have relatively low levels of medication adherence compared with other drug classes. Next, numerous statin formulations are available, each with its own unique safety and efficacy profile, and it may be unclear to prescribers which treatment is optimal for their patients. Finally, statins have class-wide side effects of myopathy and rhabdomyolysis that have resulted in a product recall and dosage limitations. Recent evidence suggests that two genomic markers, KIF6 and SLCO1B1, may inform the therapy choice of patients initiating statins. Given the prevalence of statin usage, their potential health advantages and their overall cost to the healthcare system, there could be significant clinical benefit from creating personalized treatment regimens. Ultimately, if this approach is effective it may encourage higher adoption of generic statins when appropriate, promote adherence, lower rates of myopathy, and overall achieve higher value cardiovascular care. This paper will review the evidence for personalized prescribing of statins via KIF6 and SLCO1B1 and consider some of the implications for testing these markers as part of routine clinical care.
OBJECTIVES: To evaluate the association between social support and medication adherence. STUDY DESIGN: A search of articles published before November 2010 in peer-reviewed, healthcarerelated journals was conducted using PubMed, EMBASE, and Web of Science, and search terms related to social support (social support OR friend OR family OR agency) and adherence (patient compliance OR medication adherence), yielding 5331 articles. METHODS: Articles were included if they directly measured the relationship between medication adherence and some form of social support. Excluded were case studies, studies with participants < 18 years of age, and non-English language studies. Four social support categories were reported: structural, practical, emotional, and combination. Medication adherence was reported in the manner in which it was described in each study. RESULTS: Fifty studies were included in the final analysis. A greater degree of practical support was most consistently associated with greater adherence to medication; evidence for structural or emotional support was less compelling. However, most studies were limited in size and design, and substantial variability in designs and outcome measurement prohibited pooling of results, necessitating qualitative evaluation of the studies. CONCLUSIONS: This qualitative analysis found that practical social support was most consistently associated with greater medication adherence. Interventions that use existing contacts (friends or family) to engage patients in the mundane and practical aspects of medication purchasing and administration may be an effective approach to promoting better medication adherence.
BACKGROUND: Little is known about the use of warfarin in hemodialysis (HD) patients with atrial fibrillation (AF). We studied temporal trends of AF among older HD patients, and of warfarin use among those with AF. METHODS: We linked US Medicare and prescription claims from older patients undergoing HD in 2 Eastern US states. We established annual cohorts of prevalent HD patients; AF was ascertained from >2 claims (>7 days apart) in the same year, with a diagnosis code indicating AF. Among those with AF, we defined current and past warfarin use. Demographic and clinical characteristics were also ascertained for each cohort. We used repeated-measures logistic regression to define the odds of AF and of current or past versus absence of warfarin use. RESULTS: Of 6,563 unique patients, 2,185 were determined to have AF. The prevalence of AF increased from 26% in 1998 to 32% in 2005. In 2005, current warfarin use was present in 24% of AF patients and past use in 25%; 51% had no evidence of any warfarin use. No significant trends in utilization were observed from 1998 through 2005. Patients aged =85 years and nonwhites were less likely to have received warfarin; most comorbidities were not associated with warfarin use except for patients with past pulmonary embolism or deep venous thrombosis who were more likely than those without such history. CONCLUSION: While the prevalence of AF has been increasing among older HD patients, warfarin use was low and unchanged over time, perhaps reflecting the lack of evidence supporting its use.