Referral of patients to an anticoagulant clinic: implications for better management.

The quality of anticoagulant treatment of ambulatory patients is affected by the content of referral letters and administrative processes. To assess these influences a method was developed to audit against the hospital standard the referral of patients to one hospital anticoagulant clinic in a prospective study of all (80) new patients referred to the clinic over eight months. Administrative information was provided by the clinic coordinator, and the referral letters were audited by the researchers. Referral letters were not received by the clinic for 10% (8/80) of patients. Among the 72 referral letters received, indication for anticoagulation and anticipated duration of treatment were specified in most (99%, 71 and 81%, 58 respectively), but only 3% (two) to 46% (33) reported other important clinical information (objective investigations, date of starting anticoagulation, current anticoagulant dose, date and result of latest international normalised ratio, whether it should be the anticoagulant clinic that was eventually to stop anticoagulation, patients' other medical problems and concurrent treatment. Twenty two per cent (16/80) of new attenders were unexpected at the anticoagulant clinic. Most patients' case notes were obtained for the appointment (61%, 47/77 beforehand and 30% 23/77 on the day), but case notes were not obtained for 9% (7/77). The authors conclude that health professionals should better appreciate the administrative and organisational influences that affect team work and quality of care. Compliance with a well documented protocol remained below the acceptable standard. The quality of the referral process may be improved by using a more comprehensive and helpful referral form, which has been drawn up, and by educating referring doctors. Measures to increase the efficiency of the administrative process include telephoning the clinic coordinator directly, direct referrals through a computerised referral system, and telephone reminders by haematology office staff to ward staff to ensure availability of the hospital notes. The effect of these changes will be assessed in a repeat audit.     

The importance of establishing regimen concordance in preventing medication errors in anticoagulant care

Miscommunication between patients and providers can have serious consequences, especially where medications are concerned. We examined whether regimen discordance between patient and provider, a possible result of miscommunication, contributes to unsafe medication management. We studied 220 patients taking warfarin in an anticoagulation clinic to characterize two medication assessment methods. We measured (1) adherence by asking patients to report any missed doses and (2) concordance between patients' and providers' reports of warfarin regimens. We categorized patients as having regimen adherence if they missed no doses, and concordance if there was patient-provider agreement in weekly dosage. We characterized anticoagulant outcomes as unsafe if international normalized ratio (INR) values were <2.0 (at risk for thrombosis) or >4.0 (at risk for hemorrhage), and explored relationships among adherence, concordance, and anticoagulant outcomes. One hundred fifty-five patients (71%) reported no missed doses during the prior 30 days. Poor adherence was associated with underanticoagulation (AOR 2.33, 1.56-3.45), but not overanticoagulation (AOR 1.36, 0.69-2.66). One hundred ten patients (50%) reported regimens discordant with clinicians' report. There was no relationship between patients' reports of adherence and concordance. Among adherent patients, discordance was associated with underanticoagulation (AOR 1.67, 1.00-2.78) and overanticoagulation (AOR 3.44, 1.32-9.09). Discordance regarding warfarin regimens is common and places patients at risk for adverse events. To promote safe and effective care, clinicians should separately determine adherence and regimen concordance during routine medication assessments. Systems need to be developed to ensure concordance in medication regimens.     

Patients' understanding of anticoagulant therapy in a multiethnic population

To investigate whether knowledge and perceptions of antithrombotic therapy differ between ethnic groups in the UK, we conducted a cross-sectional questionnaire survey of patients attending anticoagulation clinics in three Birmingham teaching hospitals. 180 consecutive patients were recruited-135 white European, 29 Indo-Asian, 16 Afro-Caribbean. The average knowledge score was 5.5 out of 9, with no significant differences between the groups. Indo-Asians were significantly less likely than the other groups to know the name of the anticoagulant they were taking (warfarin) and Afro-Caribbeans to know the condition for which they were being anticoagulated. Few patients of any group were able to specify more than one side-effect of warfarin or the dose they were on. In logistic regression analysis the factors associated with a low score were age >61 years, having been born outside the UK, and the perception of difficulty in comprehension. Nearly half the Indo-Asians felt unable to understand what was said to them in the clinic, and 62% expressed a preference for a doctor of the same ethnic group. Although there were no significant between-group differences, this study points to gaps in the knowledge of patients from ethnic minorities and to deficiencies in the provision of information. In patient education, these groups should receive special attention.     

Perioperative management of patients receiving anticoagulant or antiplatelet therapy: a clinician-oriented and practical approach

The management of patients who are receiving warfarin, aspirin, clopidogrel, or combinations of these drugs and require their interruption because of an elective surgical or other invasive procedure is a common and sometimes challenging clinical problem. For the practicing clinician, there are 2 key issues for perioperative anticoagulant management: 1) having an approach to stratify patients according to their risk for thromboembolism when warfarin or antiplatelet drug therapy is interrupted, and also having an approach to stratify patients according to the risk of bleeding associated with the surgery or procedure; and 2) determining which patients may require bridging anticoagulation and, if required, how to administer bridging, typically with a low-molecular-weight heparin, before and after surgery in a manner that minimizes the risk for bleeding. The overall goal is to minimize patients' risk for thromboembolism and bleeding throughout the perioperative period. The objective of this article is to provide an evidence-based but practical approach relating to these 2 key issues in a manner than can be applied to everyday clinical practice.     

Assessment of healthcare professionals' knowledge about warfarin-vitamin K drug-nutrient interactions

OBJECTIVE: Dietary vitamin K can interact with oral anticoagulant drugs and interfere with their therapeutic safety and efficacy. Therefore, knowledge about drug-nutrient interactions involving vitamin K possessed by physicians, pharmacists, dietitians and nurses practicing anticoagulant therapy was assessed. METHODS: Healthcare practitioners were surveyed using a 30-question, 98-item questionnaire on the most common and/or important food interactions with warfarin, drug interactions with warfarin and general drug-nutrient interactions involving vitamin K. The study sample included 160 randomly selected healthcare providers (40 physicians, pharmacists, dietitians and nurses) from 10 hospitals with 200 to 1000 beds from six Massachusetts regions. Random selection was conducted from a pool of selected healthcare providers practicing anticoagulant therapy who counsel patients receiving warfarin. RESULTS: All surveys were completed within three months of the start of the study, and all participants provided usable data for statistical analysis. The mean scores (+/- SD) on the overall test were 72.5+/-9.0 for pharmacists, 62.51+/-10.6 for physicians, 56.9+/-8.8 for dietitians and 50.2+/-9.3 for nurses, with 100 being a perfect score. Pharmacists scored significantly higher in the area of drug interactions (75.9+/-11.3, p<0.05). Dietitians scored higher in the area of food interactions (73.0+/-10.3). No significant differences between physicians and pharmacists were evident on general drug-nutrient interactions. While over 87% of the healthcare professionals correctly identified some common foods containing large amounts of vitamin K, such as broccoli and spinach, fewer than 25% were able to identify others such as pea soup, coleslaw and dill pickles. CONCLUSIONS: Although the healthcare professionals surveyed in this study appear to have demonstrated some proficiency in their respective areas of expertise, they exhibited less knowledge in others. Therefore, additional training and integration of knowledge and expertise about drug-nutrient interactions among healthcare professionals are essential to provide appropriate patient counseling and optimal therapeutic outcomes.     

The Association of Health Literacy With Time in Therapeutic Range for Patients on Warfarin Therapy

Patients on warfarin therapy need to achieve and maintain anticoagulation control in order to experience the benefits of treatment while minimizing bleeding risk. Low health literacy skills may hinder patients' ability to use and adhere to warfarin in a safe and effective manner. The authors conducted this study to evaluate the relationship between health literacy and anticoagulation control among patients on chronic warfarin therapy. Participants were recruited from 2 diverse anticoagulation clinics in North Carolina. Time in therapeutic range (TTR) for warfarin therapy was used as a measure of anticoagulation control. Health literacy was assessed using the short form of the Test of Functional Health Literacy in Adults (S-TOFHLA). Of the 198 study participants, 51% had limited health literacy (S-TOFHLA score of 0–90) and 33% had poor anticoagulation control (TTR <50%). Participants with limited health literacy were less likely to correctly answer warfarin-related knowledge questions. Limited health literacy was significantly associated with TTR <50% (adjusted odds ratio = 2.34, 95% CI [1.01, 5.46]). Findings indicate that limited health literacy is associated with poor anticoagulation control for patients on warfarin therapy. Lack of medication understanding may hinder the safe and effective use of this narrow therapeutic index drug.     

Asthma And Depression

Abstract

Thromboprophylaxis with oral anticoagulants (OACs) is an important but under-used element of atrial fibrillation (AF) treatment. Reduction of stroke risk with anticoagulants comes at the price of increased bleeding risk. Patients with AF receiving anticoagulants require heightened attention with transition from one care setting to another. Patients presenting for emergency care of anticoagulant-related bleeding should be triaged for the severity and source of the bleeding using appropriate measures, such as discontinuing the OAC, administering vitamin K, when appropriate, to reverse warfarin-induced bleeding, or administering clotting factors for emergent bleeding. Reversal of OACs in patients admitted to the hospital for surgery can be managed similarly to patients with bleeding, depending on the urgency of the surgical procedure. Patients with AF who are admitted for conditions unrelated to AF should be assessed for adequacy of stroke risk prophylaxis and bleeding risk. Newly diagnosed AF should be treated in nearly all patients with either warfarin or a newer anticoagulant. Patient education is critically important with all anticoagulants. Close adherence to the prescribed regimen, regular international normalized ratio testing for warfarin, and understanding the stroke risk conferred by both AF and aging are goals for all patients receiving OACs. Detailed handoff from the hospitalist to the patient's primary care physician is required for good continuity of care. Monitoring by an anticoagulation clinic is the best arrangement for most patients. The elderly, or particularly frail or debilitated patients who are transferring to long-term care, need a detailed transfer of information between settings, education for the patient and family, and medication reconciliation. Communication and coordination of care among outpatient, emergency, inpatient, and long-term care settings are vital for patients with AF who are receiving anticoagulants to balance stroke prevention and bleeding risk.     

A new, brief questionnaire (PEQ) developed in primary health care for measuring patients' experience of interaction, emotion and consultation outcome

BACKGROUND: A deepened understanding of patients' perspectives is essential in order to improve medical communication. By changing focus from patient satisfaction to patient experiences, more immediate, personal and affective responses may be captured. OBJECTIVE: Our aim was to develop a new consultation-specific questionnaire on patient experiences. METHODS: The questionnaire was developed in Norwegian primary care in three main phases. Phase 1: focus groups with patients in order to identify important aspects of patients' experiences, and their words and language when describing such experiences. Phase 2: a questionnaire survey with 110 items including 660 patients. Extensive testing resulted in a reduction to 25 items on six dimensions. Phase 3: a questionnaire survey with 25 items including 1092 patients. Psychometric analyses and feedback from patients and physicians involved dimensionality and tests of validity and reliability. RESULTS: A final questionnaire was produced with 18 items on five dimensions: communication; emotions; short-term outcome; barriers; and relations with the auxiliary staff. The validity and reliability estimates were highly satisfactory. Three scales were skewed while two were more equally distributed. Forty-eight per cent of the patients described less than optimal communication experiences; some communication barriers were detected in 70% of the visits and less helpful experiences with the staff were reported in 55% of the visits. Twenty-four per cent of patients left with no positive feelings, and 48% scored low on the outcome scale (knowledge, perceived result). CONCLUSIONS: The patient experience questionnaire (PEQ) emphasizes what patients value the most, i.e. interaction, emotions and outcome, and may represent a valuable tool for doctors who want feedback from their patients on the function of their doctor-patient relationships.     

How patients with atrial fibrillation value different health outcomes: a standard gamble study

BACKGROUND AND PURPOSE: The assessment of any health care intervention should consider both risks and benefits and take patients' preferences about these into account. The study reported in this paper aimed to elicit patient valuations of health states relevant to assessment of the prevention of stroke by warfarin anticoagulation therapy for patients with atrial fibrillation. METHODS: A sample of patients over the age of 60 years with atrial fibrillation from three family practices in North-East England was interviewed. Their health state values were elicited using the standard gamble method for general practitioner (GP)-managed warfarin treatment, hospital-managed warfarin treatment, major bleed, mild stroke and severe stroke. RESULTS: Of 180 patients, 69 (38%) agreed to participate, of whom 57 (83%) completed interviews. Median (mean) utility values were for GP-managed warfarin treatment 0.986 (0.948), hospital-managed warfarin treatment 0.984 (0.941), major bleed 0.880 (0.841), mild stroke 0.675 (0.641) and severe stroke 0 (0.189). There was wide variation in values between patients and the distributions were highly skewed. CONCLUSIONS: The results are of value in applying decision analysis to groups of patients. They should be used with caution in reaching decisions about appropriate treatment for individual patients, but may provide a starting point for necessary further exploration of those patients' individual preferences.     

Assessment of Healthcare Professionals’ Knowledge About Warfarin-Vitamin K Drug-Nutrient Interactions

Objective: Dietary vitamin K can interact with oral anticoagulant drugs and interfere with their therapeutic safety and efficacy. Therefore, knowledge about drug-nutrient interactions involving vitamin K possessed by physicians, pharmacists, dietitians and nurses practicing anticoagulant therapy was assessed.

Methods: Healthcare practitioners were surveyed using a 30-question, 98-item questionnaire on the most common and/or important food interactions with warfarin, drug interactions with warfarin and general drug-nutrient interactions involving vitamin K. The study sample included 160 randomly selected healthcare providers (40 physicians, pharmacists, dietitians and nurses) from 10 hospitals with 200 to 1000 beds from six Massachusetts regions. Random selection was conducted from a pool of selected healthcare providers practicing anticoagulant therapy who counsel patients receiving warfarin.

Results: All surveys were completed within three months of the start of the study, and all participants provided usable data for statistical analysis. The mean scores (±SD) on the overall test were 72.5±9.0 for pharmacists, 62.5±10.6 for physicians, 56.9±8.8 for dietitians and 50.2±9.3 for nurses, with 100 being a perfect score. Pharmacists scored significantly higher in the area of drug interactions (75.9±11.3, p<0.05). Dietitians scored higher in the area of food interactions (73.0±10.3). No significant differences between physicians and pharmacists were evident on general drug-nutrient interactions. While over 87% of the healthcare professionals correctly identified some common foods containing large amounts of vitamin K, such as broccoli and spinach, fewer than 25% were able to identify others such as pea soup, coleslaw and dill pickles.

Conclusions: Although the healthcare professionals surveyed in this study appear to have demonstrated some proficiency in their respective areas of expertise, they exhibited less knowledge in others. Therefore, additional training and integration of knowledge and expertise about drug-nutrient interactions among healthcare professionals are essential to provide appropriate patient counseling and optimal therapeutic outcomes.     

Validity and reliability of a self-administered health history questionnaire.

A self-administered, health history questionnaire devised for routine use in a general medical clinic is completed without the assistance of clinic personnel and used, unedited, by the providers. The reliability and validity of the responses of 23 patients to this questionnaire were tested statistically. In our setting, more than 90 percent of the patients referred for care are capable of completing the questionnaire. The 23 patients averaged 32 minutes to complete the questionnaire. An average of 34 minutes of encounter time is required to obtain the same historical data by interview. Test-retest reliability of patients' responses to the questionnaire was 90 percent. More than 92 percent of the patients' written responses to health history items agreed with the data obtained in a blinded fashion by internists in the traditional interview. The questionnaire accurately obtains items of history frequently missing from the recorded ambulabory care data base, and in some instances obtains items of history more effectively than the interviewing physician. The study results showed a low incidence of false positive (1.8 percent) and false negative (2.8 percent) responses to questionnaire items.     

The burden of atrial fibrillation in unselected acute medical admissions

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia and is of increasing prevalence. The presence of AF complicates the management of patients presenting as medical emergencies. OBJECTIVE: To assess the prevalence of AF and current investigation and management strategies in unselected acute medical admissions. DESIGN: Prospective survey of all acute medical admissions over 22 days. SETTING: Stobhill Hospital--district general hospital in north Glasgow. SUBJECTS: Five hundred and seven consecutive acute medical admissions. RESULTS: Of the 507 patients, 47 (9.3%) had AF. AF was a new diagnosis in five patients (11.0%). The most common presenting features were dyspnoea and chest pain. The principal underlying medical conditions were hypertension and ischaemic heart disease. AF was the primary reason for admission in six patients (12.8%) and a documented reason for admission in 11 patients (23.4%). Thyroid function tests were or had previously been performed in 45 patients (95.7%). Twenty-four patients (51.1%) underwent echocardiography or had done so previously. Twenty-two patients (46.8%) received anticoagulation with warfarin. Ten patients (21.3%) should have received warfarin by standard guidelines but did not. No patient received warfarin inappropriately. Rate control was used in 40 patients (85.1%). Rhythm control was attempted in four patients (8.5%). CONCLUSION: AF is common amongst emergency admissions to district general hospitals and has significant resource implications. Improvements are needed both in the use of echocardiography and in the administration of anticoagulant therapy.     

Language, literacy, and communication regarding medication in an anticoagulation clinic: a comparison of verbal vs. visual assessment

Despite the importance of clinician-patient communication, little is known about rates and predictors of medication miscommunication. Measuring rates of miscommunication, as well as differences between verbal and visual modes of assessment, can inform efforts to more effectively communicate about medications. We studied 220 diverse patients in an anticoagulation clinic to assess concordance between patient and clinician reports of warfarin regimens. Bilingual research assistants asked patients to (1) verbalize their prescribed weekly warfarin regimen and (2) identify this regimen from a digitized color menu of warfarin pills. We obtained clinician reports of patient regimens from chart review. Patients were categorized as having regimen concordance if there were no patient-clinician discrepancies in total weekly dosage. We then examined whether verbal and visual concordance rates varied with patient's language and health literacy. Fifty percent of patients achieved verbal concordance and 66% achieved visual concordance with clinicians regarding the weekly warfarin regimen (P < .001). Being a Cantonese speaker and having inadequate health literacy were associated with a lower odds of verbal concordance compared with English speakers and subjects with adequate health literacy (AOR 0.44, 0.21-0.93, AOR 0.50, 0.26-0.99, respectively). Neither language nor health literacy was associated with visual discordance. Shifting from verbal to visual modes was associated with greater patient-provider concordance across all patient subgroups, but especially for those with communication barriers.Clinician-patient discordance regarding patients' warfarin regimen was common but occurred less frequently when patients used a visual aid. Visual aids may improve the accuracy of medication assessment, especially for patients with communication barriers.     

Apixaban for stroke prevention in atrial fibrillation: a review of the clinical trial evidence

The objective of this review is to summarize data from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) and Apixaban Versus Acetylsalicylic Acid to Prevent Stroke in Atrial Fibrillation Patients Who Have Failed or Are Unsuitable for Vitamin K Antagonist Treatment (AVERROES) trials of apixaban for stroke prevention in patients with atrial fibrillation (AF). The ARISTOTLE trial compared apixaban with warfarin in 18 201 patients with AF and ≥ 1 additional risk factor for stroke. The AVERROES trial compared apixaban with aspirin in 5599 patients with AF who were at increased risk of stroke and for whom vitamin K antagonists were unsuitable. In ARISTOTLE, apixaban reduced the risk of stroke or systemic embolism by 21% compared with warfarin (1.27% vs 1.60% per year; hazard ratio, 0.79; 95% confidence interval, 0.66-0.95). The reduction was significant and demonstrated the superiority of apixaban over warfarin for the primary outcome of preventing stroke or systemic embolism (P = 0.01 for superiority). Apixaban also reduced all-cause mortality by 11% (P = 0.047) and major bleeding by 31% (P < 0.001) compared with warfarin. The benefits of apixaban observed in ARISTOTLE are further supported by the results from AVERROES, which demonstrated a 55% reduction in the risk of stroke or systemic embolism compared with aspirin. Risk of major bleeding was not significantly different between apixaban and aspirin. Subgroup analyses in both trials demonstrated that the effects of apixaban are highly consistent across various patient subpopulations. Discontinuation of study medication was significantly lower with apixaban than with either warfarin in ARISTOTLE or aspirin in AVERROES. Apixaban is the first new oral anticoagulant that has been shown to be superior to warfarin in reducing stroke or systemic embolism, all-cause mortality, and major bleeding in patients with AF. Moreover, in patients with AF who are considered unsuitable for warfarin therapy, apixaban was more effective than aspirin for stroke prevention and had a similar rate of major bleeding.     

The Importance of Establishing Regimen Concordance in Preventing Medication Errors in Anticoagulant Care

Miscommunication between patients and providers can have serious consequences, especially where medications are concerned. We examined whether regimen discordance between patient and provider, a possible result of miscommunication, contributes to unsafe medication management.

We studied 220 patients taking warfarin in an anticoagulation clinic to characterize two medication assessment methods. We measured (1) adherence by asking patients to report any missed doses and (2) concordance between patients' and providers' reports of warfarin regimens. We categorized patients as having regimen adherence if they missed no doses, and concordance if there was patient–provider agreement in weekly dosage. We characterized anticoagulant outcomes as unsafe if international normalized ratio (INR) values were <2.0 (at risk for thrombosis) or >4.0 (at risk for hemorrhage), and explored relationships among adherence, concordance, and anticoagulant outcomes.

One hundred fifty-five patients (71%) reported no missed doses during the prior 30 days. Poor adherence was associated with underanticoagulation (AOR 2.33, 1.56–3.45), but not overanticoagulation (AOR 1.36, 0.69–2.66). One hundred ten patients (50%) reported regimens discordant with clinicians' report. There was no relationship between patients' reports of adherence and concordance. Among adherent patients, discordance was associated with underanticoagulation (AOR 1.67, 1.00–2.78) and overanticoagulation (AOR 3.44, 1.32–9.09).

Discordance regarding warfarin regimens is common and places patients at risk for adverse events. To promote safe and effective care, clinicians should separately determine adherence and regimen concordance during routine medication assessments. Systems need to be developed to ensure concordance in medication regimens.     

心房颤动住院患者抗凝治疗的回顾分析研究

目的通过对280例房颤住院患者的病历资料进行回顾性分析,旨在评价房颤患者的抗凝治疗情况。方法对我院2000年4月-2007年2月出院诊断为持续性房颤的280例患者的住院资料进行详细登记及回顾性总结,建立患者的数据库,利用SPSS软件进行分析。结果应用阿司匹林抗血小板治疗83例,发生脑栓塞14例(16.86%)。用华法林抗凝治疗的患者197例,发生脑栓塞8例(4.06%)(P<0.05),提示华发林抗凝治疗的脑卒中患者患病率低于应用阿司匹林的抗血小板治疗的患者。口服华发林过程中出现出血事件为21例,进行Logistic回归分析,结果提示与口服华发林相关的出血高危因素为慢性肝病,收缩压>160mmHg,年龄>70岁。结论华法林抗凝治疗优于阿司匹林的抗血小板治疗。口服华发林危险因素为慢性肝病,收缩压>160mmHg,年龄>70岁,单纯监测INR是不够的。     

Haplogroup analysis of vitamin-K epoxide reductase (VKORC1) gene: novel element in the optimization of anticoagulant therapy

Warfarin and acenocoumarols are the most commonly prescribed anticoagulants that is difficult to use because of the wide intra- and interpatient variation in the dose requirements, the narrow therapeutic range and the risk of serious bleeding. Vitamin K epoxide reductase (VKORC1) is the site of inhibition by coumarins. Mutations in the VKORC1 gene affect the sensitivity of the epoxy reductase enzyme for warfarin. The three main haplotypes of VKORC1 gene, *2, *3, *4, explain most of the genetic variability in warfarin dose among Caucasians. In the current paper we focus on this subject in view of our experience gained during molecular genetic tests for the main VKORC1 haplotypes in Hungarian patients with anticoagulant therapy and unusual clinical response. A total of 28 selected cases were characterized for VKORC1 G-1639A, G9041A and C6009T alleles. Genotyping has been carried out by molecular biology techniques, including PCR-RFLP assay and direct sequencing. In patients undergoing anticoagulant therapy we could identify VKORC1 *1*2, *2*2, *2*3, *1*4, *2*4 and *3*4 haplotypes. Patients with A haplotype group (14% of the studied patients) require much lower warfarin doses than other patients (2.7+/-0.2 mg/day). In our patients we found some with B haplotype group (25%) who require high warfarin dose (6.2+/-0.3 mg/day). There were also subjects bearing the A/B haplotype group (61%) with intermediate warfarin dose (4.9+/-0.2 mg/day), estimated by the haplotype analyses of the VKORC1 gene. Results presented here underline the need of VKORC1 haplotyping in anticoagulated patients with unusual clinical anticoagulant response, and the examination can have further therapeutic consequences.     

Relationship between diet and anticoagulant response to warfarin

Background Diet composition is one of the factors that may contribute to intraindividual variability in the anticoagulant response to warfarin. Aim of the study To determine the associations between food pattern and anticoagulant response to warfarin in a group of Brazilian patients with vascular disease. Methods Recent and usual food intakes were assessed in 115 patients receiving warfarin; and corresponding plasma phylloquinone (vitamin K₁), serum triglyceride concentrations, prothrombin time (PT), and International Normalized Ratio (INR) were determined. A factor analysis was used to examine the association of specific foods and biochemical variables with anticoagulant data. Results Mean age was 59 ± 15 years. Inadequate anticoagulation, defined as values of INR 2 or 3, was found in 48% of the patients. Soybean oil and kidney beans were the primary food sources of phylloquinone intake. Factor analysis yielded four separate factors, explaining 56.4% of the total variance in the data set. The factor analysis revealed that intakes of kidney beans and soybean oil, 24-h recall of phylloquinone intake, PT and INR loaded significantly on factor 1. Triglycerides, PT, INR, plasma phylloquinone, and duration of anticoagulation therapy loaded on factor 3. Conclusions Fluctuations in phylloquinone intake, particularly from kidney beans, and plasma phylloquinone concentrations were associated with variation in measures of anticoagulation (PT and INR) in a Brazilian group of patients with vascular disease. This material is based upon work supported by CNPq and by federal funds from the U.S. Department of Agriculture, Agricultural Research Service under Cooperative Agreement No. 58-1950-001 and No. 58-1950-4-401. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the authors, and do not necessarily reflect the view of the U.S. Department of Agriculture. An erratum to this article is available at .