Oral Anticoagulation Knowledge Test Research Articles

Validation of a Knowledge Test in Turkish Patients on Warfarin Therapy at an Ambulatory Anticoagulation Clinic

This study aimed to evaluate the validity and reliability of an oral anticoagulation knowledge (OAK) test in Turkish patients on warfarin therapy at an anticoagulant outpatient clinic. This study was conducted at an ambulatory anticoagulation clinic and included patients older than 18 years who had been using warfarin for at least six months. Patients' demographic and clinical data were collected. Internal consistency was calculated using the Kuder-Richardson 20 (KR-20) coefficient, and the test-retest reliability of the Turkish version of the OAK test was assessed. Patients' mean age was 59.83±11.93 (26-90) years (n=240; 133 women). The mean score of the OAK test was 14.19±3.01. The test-retest reliability of the scale (n=30) was moderate for the total score (p<0.001). The KR-20 value, a measure of internal consistency, was 0.671. Patients of a younger age and higher educational level were more likely to have higher levels of anticoagulation knowledge than patients of an older age and lower education level (p<0.05 for both comparisons). The Turkish version of the OAK test can be used to determine the patients' knowledge on oral anticoagulation.

Association between Patients’ Knowledge and Adherence to Anticoagulants, and Its Effect on Coagulation Control

Background: Warfarin requires strict monitoring by measuring prothrombin time (PT), international normalized ratio (INR), and time in therapeutic range (TTR). Several factors can lead to poor PT/INR control including vitamin K status, medication adherence, knowledge, and quality of life. The present study aims to assess patient adherence to warfarin treatment and its correlation with INR control. Methods: A cross-sectional study was conducted between October 2017 and January 2018 at Tripoli University Hospital. Data were collected by structured questionnaires which included; demographic and clinical characteristics, the Oral Anticoagulation Knowledge (OAK) test, and the Morisky Medication Adherence Scale (MMAS-8). Results: The final analysis included 88 out of 140 patients (73.33%). There were significant differences in age range, gender, marital status, and education level between the 2 groups (poor knowledge and adequate knowledge) (p < 0.05). There was a significant positive correlation between OAK test score and TTR. Overall, 76.2% of patients were adherent to warfarin (MMAS score ≥6) and 20.45% of patients were of high adherence (MMAS score of 8). The median score was 6 (IQR 6–7). A statistically significant, strong positive correlation between adherence to medication and TTR as an indicator of INR control was found (rs[86] = 0.472, p < 0.0001). Conclusion: The study addressed and identified several areas for future improvement of patient outcomes. The implementation of new approaches to enhance patient knowledge and adherence is warranted, and measures to provide treatment for all patients that require it are needed, to improve outcomes and decrease adverse drug effects.

Warfarin control in Hong Kong clinical practice: a single-centre observational study

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.

Assessment of patient knowledge on warfarin: An item response theory approach.

There are no instruments to assess the patient's knowledge of oral anticoagulation with warfarin, in which the performance of the items has been evaluated through the item response theory. To evaluate psychometric properties of the Brazilian version of the Oral Anticoagulation Knowledge Test, using the item response theory. This methodological study was developed in an anticoagulation clinic of a university hospital with a sample of 201 patients treated with warfarin. The item response theory was used to evaluate questions regarding psychometric properties and the performance of the Brazilian version of the Oral Anticoagulation Knowledge Test items. The unidimensionality hypothesis was analysed by decomposing the polychoric correlation and the Cronbach's alpha coefficient. An item characteristic curve of the 20 items of the instrument was made to identify the discrimination power of each item of the performance scale. Correlations were positive and statistically significant among the 20 items, with a Cronbach's alpha coefficient of 0.82. The difficulty parameter ranged from -4.14 to 0.42. The discrimination parameter ranged from 0.41 to 1.89. The items regarding drug-drug/drug-food interactions were able to differentiate knowledge about oral anticoagulation with greater accuracy. This study is the first that uses this methodology to evaluate the knowledge on oral anticoagulation therapy with warfarin. The evaluation using item response theory showed that the Brazilian version of the Oral Anticoagulation Knowledge Test is suitable for assessing the patient's knowledge of oral anticoagulation with warfarin. Thus, our findings confirmed the utility of this instrument and provided an essential point of reference for the structuring of health education activities that ensure the individualization of educational interventions in patients on warfarin.

Effect of warfarin education on patient knowledge and anticoagulation control: a randomised controlled trial

AbstractBackgroundPatient 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.

Cross-cultural Adaptation of the Oral Anticoagulation Knowledge Test to the Brazilian Portuguese.

Patients' knowledge about oral anticoagulant therapy may favor the achievement of therapeutic results and the prevention of adverse pharmacotherapy-related events. Brazil lacks validated instruments for assessing the patient's knowledge about treatment with warfarin. This study aimed to perform the cross-cultural adaptation of the Oral Anticoagulation Knowledge (OAK) Test instrument from English into Portuguese. This is a methodological study developed in an anticoagulation clinic of a public university hospital. The study included initial translation, synthesis of translations, back-translation, review by the experts committee and pre-testing with 30 individuals. We obtained semantic equivalence through the analysis of the referential and general meaning of each item. The conceptual equivalence of the items sought to demonstrate the relevance and acceptability of the instrument. The process of cross-cultural adaptation produced the final version of the OAK Test in Brazilian Portuguese entitled "Teste de Conhecimento sobre Anticoagulação Oral". There was a suitable semantic and conceptual equivalence between the adapted version and the original version, as well as an excellent acceptability of this instrument.

Assessment of psychometric properties of the Brazilian version of the oral anticoagulation knowledge test.

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.

Association Between Patient Knowledge of Anticoagulation, INR Control, and Warfarin-Related Adverse Events

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 &gt;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.

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

BackgroundWhether level of knowledge of anticoagulation (AC) among patients on warfarin plays a role in maintenance of therapeutic INR or in warfarin-related adverse events is controversial. Most studies conducted on this subject had small patient sample sizes and did not use validated questionnaires to assess patients' knowledge of AC. ObjectivesTo use the validated Oral Anticoagulation Knowledge (OAK) test (Zeolla MM, 2006) to assess knowledge of AC among patients attending a busy AC clinic, and to examine associations between level of knowledge, INR control and adverse events. We hypothesized that patients with higher OAK test scores (i.e. greater knowledge) would have better INR control (primary outcome) and fewer bleeding and thrombosis events (secondary outcomes). MethodsConsecutive patients who had been followed in our AC clinic (tertiary care, university-affiliated hospital, 20,000 patient-visits per year) for at least one year and consented to participate were asked to complete the OAK test. The OAK test is a 20-question multiple-choice questionnaire that assesses patients' knowledge of warfarin AC. A passing score is ≥15 correct responses. Patient charts were reviewed to obtain data on clinical and demographic characteristics, and information on INR values and any thrombosis or bleeding events during the preceding 1 year period. Associations between OAK scores and patient characteristics, INR control and bleeding/thrombosis events were assessed by chi-square and t-tests, as appropriate. ResultsAmong 252 patients screened for participation, 225 met the inclusion criteria and completed the OAK test. Mean (SD) age was 70 (13.4) years, 53% were male and 75% were on warfarin for >3 years. Indications for AC were atrial fibrillation in 65%, VTE in 8%, mechanical heart valve in 10%, and other in 19%. The mean OAK score was 12/20, and 64% failed the OAK test. Predictors of a pass score on the OAK test were younger age (p= 0.01) and higher level of education (p=0.03). Over the preceding year, 57.3% of INRs were therapeutic, 25.1% subtherapeutic and 17.4% supratherapeutic, and there were 22 bleeding events and 5 thrombosis events. There was no association between OAK score and INR control, or OAK score and bleeding or thrombosis events. ConclusionTo our knowledge, this is the first study to use the validated OAK test to assess patients' AC knowledge. We found that younger and more educated patients were more likely to pass the OAK test; however, OAK test result did not predict INR control or occurrence of bleeding or thrombotic events. The OAK test may not be sensitive enough to capture the standard of care practiced in different anticoagulation clinics (e.g. differences in teaching material, frequency of INR checks in stable patients). Also, for some patients, AC knowledge among their caretakers may be more important than self-knowledge. Further research is needed to assess the relationship between AC knowledge, INR control and adverse clinical outcomes. Disclosures:No relevant conflicts of interest to declare.

Impact of a Pharmacist‐Led Warfarin Self‐Management Program on Quality of Life and Anticoagulation Control: A Randomized Trial

To evaluate the impact of a pharmacist-led warfarin patient self-management program on quality of life and anticoagulation control compared with management in a physician-led specialized anticoagulation clinic. Prospective, randomized, controlled, open-label trial. Tertiary care academic medical center. A total of 114 patients aged 18-75 years who were followed at a specialized anticoagulation clinic, had received warfarin for at least 6 months, and were expected to continue warfarin for a minimum of 4months. All patients attended an educational session on anticoagulation provided by a pharmacist. Patients randomized to the self-management group (58 patients) also received practical training to use the CoaguChek XS device and a self-management dosing algorithm. Patients in the control group (56 patients) continued to undergo standard management at the anticoagulation clinic. Patients completed a validated quality-of-life questionnaire and the validated Oral Anticoagulation Knowledge test at the beginning and end of the study. The quality of anticoagulation control was evaluated by using the time spent in therapeutic range. After 4 months of follow-up, a significant improvement in the self-management group was observed compared with the control group in four of the five quality-of-life topics (p<0.05). Improvements in knowledge were observed in both groups after the training session and persisted after 4 months (p<0.05 for all). The time spent in the therapeutic range (80.0% in the self-management group vs 75% in the control group, p=0.79) and in the extended therapeutic range ([target international normalized ratio±0.3] 93.2% in the self-management group vs 91.1% in the control group, p=0.30) were similar between groups. A self-management warfarin program led by pharmacists resulted in significant improvement in the quality of life of patients receiving warfarin therapy as well as a reduction in the time required for anticoagulation monitoring, while maintaining a level of anticoagulation control similar to a high-quality specialized anticoagulation clinic.

The benefits of pharmacist-delivered warfarin education in the home

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.

Assessing Anticoagulation Knowledge in Patients New to Warfarin Therapy

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.

Development and Validation of an Instrument to Determine Patient Knowledge: The Oral Anticoagulation Knowledge Test

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.