Prevalence and Factors Associated with Non-Adherence to Warfarin Treatment: A Single Center Study in Sri Lanka

Background: Whether the level of patient’s knowledge about warfarin plays any role in maintenance of therapeutic international normalized ratio (INR) is controversial. Several studies have looked at patients’ warfarin knowledge and the level of patients’ anticoagulation control (AC). Most studies had small numbers and did not use validated questionnaires. Objectives: To use the Oral Anticoagulation Knowledge (OAK) test to assess patients’ knowledge of AC and to examine associations between knowledge, INR, and adverse events. Methods: In this cross-sectional study, patients were asked to complete the OAK test. Data on clinical and demographic characteristics, INR values, and thrombosis or bleeding events during the preceding 1 year period were collected. Associations between OAK scores, patient characteristics, proportion of therapeutic INRs, and bleeding/thrombosis events were assessed. Results: A total of 225 patients completed the OAK test. Mean (SD) age was 70 (13.4) years, 53% were male, and 75% were on warfarin for >3 years. Over the preceding year, 57.3% of INRs were therapeutic, and there were 22 bleeding and 6 thrombotic events. The mean OAK score was 12/20 (passing score = 15/20); 64% of patients failed the OAK test. Predictors of passing the OAK test were younger age ( P = .01) and higher level of education ( P = .03). There was no association between OAK score and proportion of therapeutic INRs, or OAK score and bleeding or thrombosis events. Conclusion: We used the OAK test to assess patients’ AC knowledge. Results suggests that while younger and more educated patients were more likely to pass the OAK test, the OAK test results may not predict INR control or occurrence of bleeding or thrombotic events.

Warfarin is highly efficacious for the treatment and prevention of thromboembolic disorders. However, anticoagulation control has been a long-standing challenge, as patients' lack of knowledge of warfarin therapy is a predictor of nonadherence and compromised patient safety. To ascertain whether hospitalized patients newly initiated on warfarin are provided adequate anticoagulation education during hospitalization, as measured at discharge, as well as determine whether there is a difference in the knowledge obtained by patients educated via a structured program versus those counseled by "usual care." A prospective evaluation of warfarin education of inpatients new to warfarin therapy was performed at Bassett Medical Center, Cooperstown, NY. Patients who were admitted to the hospital and receiving warfarin for any given diagnosis, were >18 years of age and able to give informed consent, and spoke English were recruited. Patients with dementia or cognitive impairment, those who were pregnant, or those who had previously been on warfarin therapy were excluded. Recruited patients received warfarin education in the form of a structured program provided by a pharmacist or counseling by usual care during hospitalization. Prior to discharge, the Oral Anticoagulation Knowledge (OAK) test, a prevalidated tool used to measure warfarin knowledge, was administered to evaluate outcomes. Further warfarin education was provided posttest if necessary. The intervention group (n = 20) scored significantly higher on the OAK test than the usual care group (n = 20): 74% versus 55%, respectively (p = 0.004). This preliminary study demonstrated that there is a large amount of variability regarding patient knowledge of warfarin on discharge from an inpatient facility. A formalized inpatient warfarin education program may empower patients to achieve a larger degree of initial warfarin knowledge than those educated by usual care. Previous studies have demonstrated that this may improve adherence and subsequently increase long-term safety associated with oral anticoagulation. Larger, prospective, randomized studies are necessary to further evaluate patient education and safety outcomes.

Patients' Knowledge Of Anticoagulation and Its Association With Clinical Characteristics, INR Control and Warfarin-Related Adverse Events

Good warfarin knowledge is important for optimal patient outcomes, but barriers exist to effective education and warfarin knowledge is often poor. This study aimed to explore the educational outcomes of home-based warfarin education provided by trained pharmacists. In a prospective, non-randomised, controlled cohort trial, patients received either usual community-based post-discharge care or a post-discharge warfarin management service, including warfarin education by trained pharmacists during two or three home visits. Patients' warfarin knowledge was assessed at 8 and 90 days post-discharge using the Oral Anticoagulation Knowledge test. One hundred and thirty-nine patients were recruited into the usual care group between November 2008 and August 2009, and 129 into the intervention group between May and December 2009. Pharmacist-delivered warfarin education was associated with a significant difference between the intervention patients' baseline and day 8 mean warfarin knowledge scores of 64.5% (95% confidence interval (CI) 61.0-68.5%) and 78.0% (95% CI 74.5-81.5%; P < 0.001), respectively. The intervention patients also scored significantly higher than the usual care patients at day 8 (65.0%, 95% CI 61.5-68.0%; P < 0.001), but not at day 90. Use of an existing healthcare framework overcame several systemic barriers by facilitating warfarin education in patients' homes. While the intervention was associated with better short-term warfarin knowledge, follow-up may be required to optimise its benefits. Widespread implementation of home-based warfarin education by pharmacists has the potential to contribute significantly to improved outcomes from warfarin therapy.

Studies examining the relationship between patient knowledge regarding warfarin therapy and its safe and effective use are limited by the lack of validated knowledge assessment tools. To develop and validate an instrument to assess patient knowledge regarding oral anticoagulation therapy. Four nationally recognized anticoagulation experts participated in the instrument development process to ensure content validity. The Oral Anticoagulation Knowledge (OAK) test was administered to subjects on warfarin and a group of age-matched subjects not on warfarin to assess construct validity. A subgroup of warfarin subjects were retested approximately 2-3 months after initial testing to assess test-retest reliability. Internal consistency reliability was assessed by calculating a Kuder-Richardson 20 value. Item analysis was used to assess performance of individual questions. An initial 23 item instrument was pilot tested for readability and comprehension. The OAK test was administered to 74 subjects taking warfarin and 27 age-matched subjects not on warfarin. Thirty-two subjects on warfarin repeated the OAK test an average of 75 days following initial administration. Subjects taking warfarin scored significantly higher than those not on warfarin (72% vs 52%, respectively; p < 0.001), supporting the construct validity of the instrument. Test-retest reliability was acceptable, with a Pearson's correlation coefficient of 0.81. Internal consistency reliability was confirmed by a calculated Kuder-Richardson 20 value of 0.76. The OAK test is a brief, valid, and reliable knowledge assessment instrument that may be a useful tool for research and clinical practice to augment patient education programs.

BackgroundPatient education is a key component of management in the anticoagulated patient.AimThe aim of this study was to establish whether reiteration of warfarin education in the outpatient setting affects patients’ knowledge of warfarin and anticoagulation control.MethodsThe study was a randomised prospective trial. Participants newly commenced on warfarin at The Royal Melbourne Hospital were randomised to either standard inpatient education (n = 19) or to receive an additional comprehensive warfarin education session (n = 21). The primary outcome was warfarin knowledge as assessed by the Oral Anticoagulation Knowledge (OAK) test. Secondary outcomes were time in therapeutic range (TTR) and complications. The duration of follow‐up was 6 weeks.ResultsThere were no significant differences between the intervention and control groups in OAK test scores (16.3/20 vs 14.4/20, respectively; p = 0.07), TTR (56.9% vs 59.3%, respectively; p = 0.09) or in the incidence of complications.ConclusionWithin the limitations of a single‐centre, underpowered study, we did not detect any significant additional benefit to patient knowledge from further outpatient warfarin education. Current standard inpatient education at our centre compared favourably with other such designed interventions outlined in previous studies. Nevertheless, it is possible that certain subsets of the population may benefit from additional education, such as those with mild cognitive impairment and those from non‐English‐speaking backgrounds; however, a much greater sample size would be required to study these groups.

The aim of this cross-sectional study is to assess community pharmacists' knowledge of the therapeutic aspects of direct oral anticoagulants and warfarin. Another objective was to study the effect of different demographic factors and relevant characteristics on community pharmacists' knowledge of warfarin and direct oral anticoagulants. The study was conducted prospectively at community pharmacies in the north of Jordan. Community pharmacists were interviewed using a validated questionnaire consisting of three sections. The first section included demographics and other relevant characteristics. The second and third sections included questions about direct oral anticoagulants and warfarin respectively. A total of 251 participants completed the questionnaire. Two-thirds of participants knew that direct oral anticoagulants are available in Jordan (67.3%). Of the pharmacists who were able to state at least one direct oral anticoagulant, 60.9% knew at least one main indication. More than half of participating pharmacists had insufficient knowledge (57.8%). Almost half of participants (48.6%) were able to state the most important monitoring parameter of warfarin, and 30.7% were able to state one medication that interacts with warfarin. More than half of participating pharmacists had insufficient knowledge (64.9%). In addition, the results showed that degree of pharmacy, years of experience, university from which pharmacy degree was obtained, and year of graduation were significantly associated with warfarin knowledge. Most participating pharmacists had insufficient knowledge with regards to direct oral anticoagulants and warfarin. Doctor of Pharmacy degree were more knowledgeable with regards to warfarin compared to participants with a bachelor's degree in Pharmacy. Continuing educational programs are required to keep community pharmacists up to date with new developments in the pharmaceutical field.

Time in therapeutic range (TTR) assesses the safety and effectiveness of warfarin therapy using the international normalised ratio. This study investigated the TTR in Hong Kong patients using both European and Japanese therapeutic ranges and patients' economic and clinical outcomes. Predictors of poor warfarin control and patient knowledge concerning warfarin therapy were assessed. A 5-month observational study with retrospective and prospective components was conducted in the Prince of Wales Hospital. The study examined electronic patient records of patients who received warfarin for at least 1 year during the period from January 2010 to August 2015. Patient knowledge was assessed via phone interview using the Oral Anticoagulation Knowledge (OAK) test. In total, 259 patients were included; 174 completed the OAK test. The calculated mean TTR was 40.2±17.1% (European therapeutic range), compared with 49.1±16.1% (Japanese therapeutic range) [P<0.001]. Mean TTR was higher in patients with atrial fibrillation than in patients with prosthetic heart valve (P<0.001). The abilities of TTR to predict clinical and economic outcomes were comparable between European and Japanese therapeutic ranges. Patients with ideal TTR had fewer clinical complications and lower healthcare costs. Patients with younger age exhibited worse TTR, as did those with concurrent use of furosemide, famotidine, or simvastatin. Mean OAK test score was 54.1%. Only 24 (13.8%) patients achieved a satisfactory overall score of ≥75% in the test. Warfarin use in Hong Kong patients was poorly controlled, regardless of indication. Patient knowledge concerning warfarin use was suboptimal; thus, additional patient education is warranted regarding warfarin.

Background: Warfarin is the most commonly used oral anticoagulant for patients with atrial fibrillation, prosthetic heart valves, and deep vein thrombosis with a narrow therapeutic index. Due to the importance of patients’ adherence to treatment and also regular measurements of International normalized ratio (INR), this can have a significant impact on the quality of anticoagulation control. Objectives: The primary aim of this study was to assess the association between warfarin knowledge and time in therapeutic range (TTR) in patients on warfarin anticoagulation for at least 6 months who were referred to anticoagulation clinic in Rajaie Heart Center during 2016 - 2017. Methods: In this cross-sectional study, 620 patients who had been referred to the outpatient Rajaie Hospital anticoagulant clinic and had been taking warfarin for over six months were asked to fill two questionnaires named anticoagulation knowledge assessment (AKA) during a 12-week period. After obtaining the necessary permits, TTR (by Rosendal method) was calculated using the INR results of patients. Results: A total of 620 patients completed the questionnaire. The relation between warfarin knowledge and anticoagulation control was not significant. The mean age of the study population was 52.45 SD ± 14.01 years. This study showed a significant relationship between TTR, duration of warfarin usage (PV = 0.03) and the underlying cause of this usage (PV = 0.016). Conclusions: Prevention of chronic diseases is one of the most important priorities of the health care systems. Reduction in complications such as thrombosis and bleeding can be achieved by efforts to promote patient’s knowledge. By recognition of relation between warfarin knowledge and social and demographic indicators, patient’s education gap can be detected and also planned for dissolving. This study showed that although many of the patients visited in anticoagulation clinic have poor anticoagulation control, but a major part of them have good knowledge of warfarin usage.

Purpose: To assess the level of knowledge on warfarin therapy and anticoagulation control, and explore the association between knowledge and anticoagulation control in a section of Saudi population. Methods: A cross-sectional prospective survey was conducted over a 4-week period in 2013 at King Khalid University Hospital outpatient anticoagulant clinic in Riyadh, Saudi Arabia. Adult patients who were either discharged on warfarin or taking warfarin and attending the outpatient anticoagulant clinic for ≥ 6 months were invited to participate in the study. A questionnaire was used to collect the demographic data and knowledge of warfarin therapy (8-item). International Normalized Ratio (INR) readings were obtained from electronic-laboratory database. Good knowledge of warfarin was defined as a score of ≥ 75 % and good (INR) control was defined as ≥ 75 % Time INR in therapeutic range (TTR) calculated using Rosendaal method. Results: A total of 105 patients completed the questionnaire with a response rate of 49.2 %. Seventy nine patients (75.2 %) had good knowledge of warfarin (scored ≥ 75 %), but only 35 patients (33.3 %) had good anticoagulation control (TTR ≥ 75 %). An association was observed between patients with no formal education and poor warfarin knowledge (p = 0.012). Smoking history was also linked with warfarin knowledge (p = 0.025). INR control results significantly differed by marital status with divorced/widow status displaying poor INR control (p = 0.028). Lastly, no association was found between good knowledge and good INR control (OR 1.35, 95 %; CI 0.537 – 3.392). Conclusions: The majority of patients seen at the outpatient anticoagulation clinic have good knowledge of warfarin therapy although only a third showed good anticoagulation control. The results indicate no significant association between knowledge of warfarin therapy and anticoagulation control. Studies with a larger sample size are recommended to verify the foregoing results. Keywords: Oral Anticoagulant, Warfarin, International Normalized Ratio, Knowledge, Anticoagulation Control

Warfarin Sensitivity Genotyping: A Review of the Literature and Summary of Patient Experience

Evaluation of patients' knowledge of warfarin at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia

It is not known whether electronic-learning (e-learning) is effective for educating hospital inpatients about complex medications such as warfarin. This prospective randomised controlled study compared pharmacist-facilitated e-learning with standard pharmacist-delivered face-to-face education on patients’ or their unpaid carers’ knowledge of warfarin and satisfaction with warfarin education as well as the time that was spent by pharmacists in delivering warfarin education. Adult English-speaking patients (or their carers) who had been prescribed warfarin were randomised to receive standard pharmacist face-to-face education (control) or an e-learning module on a tablet device facilitated by a pharmacist (intervention). All of the participants received written warfarin information and were presented with the opportunity to ask any questions that they may have had to a pharmacist. Fifty-four participants completed the study (27 per group). The participants who received e-learning had median correct Oral Anticoagulation Knowledge (OAK) test scores of 85% compared to 80% for standard education (p = 0.14). The participants in both groups were satisfied with the information that they received. There was a trend towards pharmacists spending less time on warfarin education for the e-learning group than in the standard education group (25.5 vs. 33 min, respectively, p = 0.05). Education delivered via pharmacist-facilitated e-learning was non-inferior in terms of patient or carer warfarin knowledge compared to standard pharmacist-delivered education.

BackgroundThe aim of this study was to evaluate the psychometric properties of the Brazilian version of the Oral Anticoagulation Knowledge (OAK) Test.MethodsThis study, conducted in an anticoagulation clinic, included 201 Brazilian participants aged over 18 years, who had been using warfarin for more than two months. The reliability of the instrument was evaluated by assessing internal consistency (Kuder-Richardson coefficient) and reproducibility (test-retest reliability). The validity was evaluated by hypothesizing that there would be a positive correlation of moderate to strong intensity between the correctness levels of the OAK Test and time within therapeutic range (TTR) values, which is a measure used to evaluate the quality of oral anticoagulation.ResultsThe instrument exhibited good psychometric properties. The total a Kuder-Richardson coefficient value was 0.818 and intraclass correlation coefficient was 0.967. The validity revealed a strong positive correlation between the values of the level of knowledge, as measured by the OAK Test and the TTR values (rs = 0.780).ConclusionThe instrument proved to be a reliable and valid tool for evaluating the knowledge of Brazilian patients on oral anticoagulation therapy with warfarin. This instrument may be incorporated into the practice of health care for substantiating the structuring of educational activities to ensure the improvement of knowledge about the use of warfarin, thereby increasing the effectiveness and safety of treatment.

PurposeWarfarin is a widely used anticoagulant with a narrow therapeutic index, and it requires close monitoring and adequate patient education. We aimed to assess the knowledge level regarding warfarin therapy among its users and to identify the factors that significantly influence anticoagulation control.Patients and methodsPatients attending the Warfarin Clinic at the Beijing Tiantan Hospital were enrolled in this study. Patients’ knowledge on warfarin was assessed using a validated Anticoagulation Knowledge Assessment (AKA) questionnaire. Patients’ responses to each question were analyzed to identify areas of improvement in current warfarin education. International normalized ratio (INR) control was defined by the time in therapeutic range (TTR) calculated using the Rosendaal method. Spearman correlation analysis was used to investigate the association between TTR and the independent variables.ResultsA total of 65 patients were enrolled in this study. Eleven questions were answered correctly by <50% of the patients. A total of 858 INR results were recorded; 432 INR values (50.3%) reached the predefined goals, and the mean TTR was 49.8%±24.8%. There were significant associations between TTR and patients’ AKA scores (R=0.356, P=0.004) and between TTR and patients’ educational levels (R=0.339, P=0.006). No significant association was observed between other factors (age and duration of anticoagulation) and TTR. The INR outcome measure was positively associated with patients’ knowledge on warfarin and their educational levels.ConclusionAreas for improvement in patient education have been identified, and processes for educational modification are currently in development.