INR Goal Attainment and Oral Anticoagulation Knowledge of Patients Enrolled in an Anticoagulation Clinic in a Veterans Affairs Medical Center

BACKGROUND: In January 2009, the Joint Commission implemented a National Patient Safety Goal (NPSG) for ambulatory care, NPSG 3E, intended to reduce harm associated with the use of anticoagulation therapy. The 2011 NPSG 3E encompasses 8 elements of performance, including requirements that each organization (a) provide education regarding anticoagulation therapy to staff, patients, and families and (b) evaluate its safety practices and take appropriate action to improve its practices. The Alvin C. York (ACY) outpatient anticoagulation clinic provides education to new patients and their families at the initial clinic visit, with follow-up reinforcement of education as needed throughout their care. OBJECTIVES: To (a) assess the knowledge level of patients receiving warfarin therapy in an anticoagulation clinic using the validated Anticoagulation Knowledge Assessment (AKA) questionnaire and (b) examine the relationship between patient anticoagulation knowledge and anticoagulation control as measured by the international normalized ratio (INR). METHODS: All ACY Veterans Affairs (VA) anticoagulation clinic patients seen during their routine visit within an 8-week recruitment period from February 2010 to April 2010 were asked to complete the AKA questionnaire. Upon voluntary consent, the questionnaire was completed by the patient either during the clinic visits or returned later by mail. Demographic and clinical data were manually extracted from the computerized patient record system and included age, gender, indication for and duration of anticoagulation therapy, goal INR range, and the 10 INR values preceding the date of consent. A passing score was defined as at least 21 correct responses on the 29-item AKA questionnaire (72.4% correct). Statistical analyses included comparisons of demographic and clinical characteristics for patients with passing versus failing scores, assessed with Pearson chi-square and Fisher's exact test, and bivariate analyses of INR control with anticoagulation knowledge, assessed with Spearman's rho correlation. INR control was defined by 3 outcome measures: number of INRs within therapeutic range, time in therapeutic range (TTR) calculated using the Rosendaal method, and standard deviation (SD) of INR values. Anticoagulation knowledge was assessed with 2 measures: total AKA score and count of correct answers to a subset of 15 AKA items deemed by the investigators to be relevant to INR control. RESULTS: Of 447 patients enrolled in the anticoagulation clinic, 260 consented to participate in the survey, of whom 185 patients completed the AKA instrument (n=171 [92.4%] by mail) and were successfully matched to patient record system data. 178 (96.2%) respondents were male with a mean (SD) age of 68 (10.1) years. The majority of patients were undergoing anticoagulation treatment for atrial fibrillation (n=113, 61.1%) or deep venous/pulmonary thromboembolism (n=48, 25.9%). The majority of patients had been treated with warfarin for at least 1 year (n = 162, 87.6%). Most patients had goal INR ranges of 2.0 to 3.0 (n=166, 89.7%). Of the 185 patients who completed the questionnaire, 137 (74.1%) achieved a passing score. The mean (SD) AKA questionnaire score was 78.1% (12.1%). There were 8 questions that were answered correctly by less than 70% of patients and identified as potential deficiencies in patient education. For the 167 patients who had been on warfarin therapy for at least 6 months and had 10 previous INR values, there was no significant Spearman's rho correlation between total number of correct questionnaire responses and INR control, defined as the count of the 10 previous INR values within goal range (rho=0.022, P=0.776), TTR (rho=0.015, P=0.848), and SD (rho=0.047, P=0.550). There was also no significant relationship between number of correct INR-relevant responses and INR control by any of the 3 outcome measures (count in range rho=0.033, P=0.676; TTR rho=0.067, P=0.388; and SD rho=0.029, P=0.708). CONCLUSIONS: Although 74.1% of patients on long-term warfarin therapy achieved a passing score of at least 21 correct answers on the 29-question AKA instrument, there was no significant relationship between patient warfarin knowledge and INR control. Areas for improvement in patient education have been identified and procedures for educational modification are currently in development.

• Numerous factors complicate the clinical outcomes of warfarin therapy, such as concurrent disease states, drug regimens, diet and alcohol intake, physical illnesses, compliance, and patient knowledge of their responsibilities in therapy. • In a study of patients aged 80 years or older treated with warfarin, Kagansky et al. (2004) found that insufficient education as perceived by the patient or caregiver was associated with a higher rate of major bleeding events (5.2 per 1,000 patient-months) compared with no education (1.1 per 1,000 patient-months) and education that was patient-rated as sufficient (0.5 per 1,000 patient-months; P < 0.001). • Tang et al. (2003) found a slightly positive Pearson correlation (r) between knowledge about warfarin and the number of international normalized ratio (INR) values within target range (r = 0.2; P = 0.024), indicating that 4% of variance in INR could be explained by the patient's warfarin knowledge. • To date, 2 questionnaires measuring patient knowledge of anticoagulation therapy have been validated: the Oral Anticoagulation Knowledge (OAK) test, created and validated by Zeolla et al. (2006), and the Anticoagulation Knowledge Assessment (AKA) questionnaire, designed and validated by Briggs et al. (2005). No analysis of the relationship between patient knowledge of warfarin therapy and therapeutic goal achievement has used a validated instrument.

INR Goal Attainment and Oral Anticoagulation Knowledge of Patients Enrolled in an Anticoagulation
Clinic in a Veterans Affairs Medical Center OBJECTIVES: To (a) assess the knowledge level of patients receiving warfarin therapy in an anticoagulation clinic using the validated Anticoagulation Knowledge Assessment (AKA) questionnaire and (b) examine the relationship between patient anticoagulation knowledge and anticoagulation control as measured by the international normalized ratio (INR).
METHODS: All ACY Veterans Affairs (VA) anticoagulation clinic patients seen during their routine visit within an 8-week recruitment period from February 2010 to April 2010 were asked to complete the AKA questionnaire. Upon voluntary consent, the questionnaire was completed by the patient either during the clinic visit or returned later by mail. Demographic and clinical data were manually extracted from the computerized patient record system and included age, gender, indication for and duration of anticoagulation therapy, goal INR range, and the 10

INR Goal Attainment and Oral Anticoagulation Knowledge of Patients Enrolled in an Anticoagulation Clinic in a Veterans Affairs Medical Center
warfarin therapy and the percentage of international normalized ratio (INR) values within therapeutic goal range (r = 0.20, P = 0.024). 10 Additionally, in a study of patients aged 80 years or older, Kagansky et al. (2004) found that insufficient education on oral anticoagulation therapy (as perceived by the patient or caregiver) was a significant predictive factor for major bleeding events (5.2 per 1,000 patient-months) compared with no education (1.1 per 1,000 patient-months) and education that was patient-rated as sufficient (0.5 per 1,000 patient-months, P < 0.001). The percentage of INRs within the therapeutic range was highest among patients with perceived satisfactory education (45.1%) compared with those who perceived their education as insufficient (34.9%) or received no education (20.0%, P < 0.001). 11 However, not all studies have found a positive correlation between patient knowledge and outcomes of warfarin therapy. Davis et al. (2005) found that adherence to therapy with warfarin was significantly associated with anticoagulation control, defined as the number of blood tests in appropriate therapeutic range divided by the number of blood tests performed during the 60-day period; however, knowledge of warfarin therapy, assessed with an 18-question multiple-choice test, was not associated with anticoagulation control. 12 Only 14% of patients in the study by Davis et al. achieved good anticoagulation control, defined as more than 70% of INR values within therapeutic range. 12 The major limitation of all of the aforementioned studies, regardless of their results, was the use of a nonvalidated questionnaire or survey to evaluate patient knowledge. Validation indicates that the questionnaire has been thoroughly tested for content validity, measures of question difficulty, readability, and item/person reliability. To date, 2 questionnaires measuring patient knowledge of warfarin therapy have been validated: the Oral Anticoagulation Knowledge (OAK) test, created and validated by Zeolla et al. (2006), 13 and the Anticoagulation Knowledge Assessment (AKA) questionnaire, designed and validated by Briggs et al. (2005). 14 Evaluation of current patient knowledge is the first step to improving the quality of anticoagulation therapy and patient care. Deficiencies in patient knowledge can be identified and addressed, creating an ongoing system of quality improvement for anticoagulation monitoring and patient safety. The present study assessed the current knowledge level of patients receiving warfarin therapy in the outpatient anticoagulation clinic at the Alvin C. York (ACY) campus of the Veterans Affairs (VA) Tennessee Valley Healthcare System (TVHS). Study investigators conducted this research to determine if corrective actions were needed to improve patient knowledge in accordance with the standards of NPSG 3E element number 8. Additionally, to date no published studies have used a validated instrument to assess the association of patient anticoagulation knowledge with INR control. Therefore, the present study assessed A nticoagulation with warfarin is a well-established and crucial intervention for the prevention and treatment of thromboembolic events. 1,2,3 Numerous factors can affect the clinical response to anticoagulants, particularly warfarin, such as a patient's concurrent disease states, drug regimens, diet and alcohol consumption, physical illnesses, compliance, and overall knowledge of therapy. [1][2][3][4] For this reason, patients require a skillful heath care provider in addition to a systematic approach to ensure proper patient follow-up during the initiation and continuation of warfarin therapy.
Reflecting these needs, in 2009 the Joint Commission created a National Patient Safety Goal (NPSG) 03.05.01 (or 3E) for ambulatory care to "reduce the likelihood of patient harm associated with the use of anticoagulation therapy." 5,6 The 2011 NPSG 3E guidelines describe patient education as "a vital component" of a warfarin therapy program, stating that providers should make sure patients understand risks involved with therapy, precautions to take, and the need for close follow-up ( Figure 1). Element number 7 of NPSG 3E requires that the organization provide education regarding anticoagulation therapy to staff, patients, and families. Element number 8 requires that "the organization evaluate anticoagulation safety practices, take appropriate action to improve practices, and measure the effectiveness of those actions." 6,7 To date, a few studies have shown an association between the outcomes of anticoagulation therapy and health literacy, patient education, or knowledge of warfarin therapy; however, results are mixed. 8

■■ Methods Study Design and Setting
This was a single-center cross-sectional analysis of all current patients in the VA TVHS ACY anticoagulation clinic. This study was approved by the Institutional Review Board and Research and Development committees within TVHS. The outpatient anticoagulation clinic at the ACY campus of the VA TVHS was established in 2007 and is currently staffed with a doctor of pharmacy and a licensed practical nurse. Since initiation of the ACY anticoagulation clinic, patients and/or their primary caregivers are educated by the clinical pharmacy specialist at their first visit regardless of length of warfarin therapy prior to their initial clinic visit. At the time of this study, there were 447 patients enrolled in the anticoagulation clinic.

Study Sample
All 447 ACY clinic patients seen during their routine visits within an 8-week recruitment period from February 2010 to April 2010 were asked by the clinical pharmacy specialist to complete the AKA questionnaire. Patients were excluded if they refused participation, could not voice understanding after reading the informed consent, or if the study investigators felt in their best clinical judgment that the patient did not understand consent. Patients without at least 10 INR readings from the ACY clinic prior to the consent date and patients who had been enrolled in the clinic less than 6 months were eligible to complete the AKA questionnaire but were not included in the data analysis of the relationship between INR control and warfarin knowledge.

Study Procedures
Once consent was received, the AKA instrument was given to the patient. Patients were instructed to complete the questionnaire independently and without assistance. The patient could either fill out the questionnaire while in the office or take it home and mail it back to the clinic. If the patient requested to complete the survey at home, a postage-paid self-addressed envelope was provided for the return of the completed survey. Surveys were coded sequentially upon order of consent and paired with patient identifiers. This step was performed so that demographic data and the patient's 10 INR measurements could be extracted manually from the computerized patient record system (CPRS) at a later date. Missing answers in survey responses were scored as incorrect answers. Results of the AKA instrument as completed by the enrolled patients were  compiled with demographic and clinical information, including indications for anticoagulation and duration of warfarin treatment, from the patients' medical records. Two different scoring methods for the AKA instrument were used to assess correlation of warfarin knowledge with INR control. The first was the total count of correct answers for the instrument, with a maximum of 29. The second scoring method eliminated questions that were deemed by the investigators to be of limited relevance to INR control, for a total maximum score of 15 (Appendix).

Statistical Analysis
Associations between the independent variables and passing versus failing score, measured as a binomial, were assessed using Fisher's exact test or Pearson chi-square test for categorical variables. Because the data were not normally distributed, Spearman's rho correlation analysis was used instead of a Pearson correlation to assess the relationships between each of the 3 measures of INR control and both measures of anticoagulation knowledge. Analyses were performed with an a priori alpha value of 0.05 using SPSS version 17.0 (SPSS Inc., Chicago, IL) and the GraphPad InStat statistical package (GraphPad Software Inc., La Jolla, CA).

■■ Results
Of the 260 anticoagulation clinic patients who consented during the 8-week enrollment period, 186 (71.5%) returned a completed questionnaire (Figure 2). One patient was lost due to the inability to match his or her questionnaire with patient identifiers for data extraction purposes, leaving 185 patients for data analysis. Demographic and clinical data are in Table 1 Of the 185 patients who completed the 29-item AKA questionnaire, 137 (74.1%) achieved a score of at least 21 correct items (72.4%). The mean (SD) AKA questionnaire score was 78.1% (12.1%), representing approximately 22.6 correct responses. Eight questions were answered correctly by less than 70% of patients (Table 2). No patient achieved a score of 100%. For the correlation analyses, 11 patients who had been treated for 6 months or less and 7 patients with an insufficient number of INRs were excluded, leaving a total of 167 patients for data analysis. Demographic and clinical characteristics of patients included in the correlation analyses are shown in Table  3. Comparing subgroups categorized by passing versus failing AKA score, no statistically significant between-group differences were found.

INR Goal Attainment and Oral Anticoagulation Knowledge of Patients Enrolled in an Anticoagulation Clinic in a Veterans Affairs Medical Center
Spearman's rho correlation (rho) analyses (Table 4)

■■ Discussion
Currently 2 anticoagulation knowledge questionnaires have been validated for content validity, construct validity, and reliability. The AKA questionnaire used a review of published literature and anticoagulation clinic protocols, as well as interviews with anticoagulation pharmacists for content validity. AKA investigators created a 29-item instrument covering 9 content areas, including medication, medication administration, medication interactions, activity, diet, side effects, informing health  72.4% (21 of 29) of questions answered correctly, we found that 74.1% of our patients achieved a passing score. However, patient education methods and study methodology for the previous studies varied among anticoagulation clinics and patient samples, making direct comparison of study results difficult.

INR Goal Attainment and Oral Anticoagulation Knowledge of Patients Enrolled in an Anticoagulation Clinic in a Veterans Affairs Medical Center
Eight questions were answered correctly by less than 70% of patients. Four frequently missed questions covered dietary modifications; 2 addressed medication information; 1 addressed side effects; and 1 addressed informing health care providers. The 4 most frequently missed questions were evaluated for possible causes of patients' incorrect answers. Question 5 addressed dietary modifications, and 59 (31.9%) patients picked the answer indicating that green leafy vegetables should be avoided completely instead of the choice for dietary consistency from week to week. Question 16 also addressed dietary concerns with 63 (34.1%) patients choosing orange juice instead of nutritional supplement as the agent that can decrease effectiveness of warfarin. This problem could have been due to confusion over discussion in the clinic regarding other juices, such as cranberry and grapefruit, which can increase the anticoagulant effect of warfarin. On question 25, another dietary evaluation, 44 (23.8%) and 73 (39.5%) patients, respectively, answered celery and green beans instead of cole slaw for having the most effect on their warfarin therapy. Finally, the outcomes for question 26 reflected a conflict in the teaching styles of the ACY clinic staff and the investigators who created the AKA questionnaire. The question asked patients what they should do if they had both brand and generic warfarin at home. The correct answer was to take one or the other but not both.
However, another answer stated not to take either until speaking with their health care professional. Patients in the ACY clinic are taught to call the clinic with any questions they may care providers, procedures, and lab monitoring. For content validity they used the Marzano's Taxonomy. For reliability and overall analysis of their instrument, they used the Rasch dichotomous model. 14 The AKA questionnaire was employed in our study because of its range of topics important in warfarin education. Patient responses provide objective data about different aspects of practice that are taught in patient education. Thus, the instrument served as a good quality control measure of patient counseling effectiveness.
Evaluation of anticoagulation knowledge has yielded undesirable pass rates in previous literature. Using a novel survey containing 7 open-ended questions, Tang et al. found that only 18% of patients achieved a passing score of at least 70%. 10 Davis et al. found that 37% of patients achieved a passing score of at least 70% on a novel 18-question multiple-choice test. 12 Using a previously created 20-question true-or-false questionnaire, Hu et al. (2006) found a 39% pass rate, defined as a score of at least 80%. 18 In using the AKA questionnaire in the ACY VA TVHS anticoagulation clinic and defining a passing score as at least   been answered. If a similar study is conducted in the future, it would be beneficial for patients to complete the questionnaire in a standardized, monitored environment and have completion of the entire questionnaire verified before submission to prevent these limitations from recurring. Third, of 447 patients treated in the clinic, 260 consented, but not all 187 nonconsenting patients refused participation. Some were excluded by the investigators because of inability to voice understanding of the project or because the investigators determined, using their best clinical judgment, that the patient would be unable to understand consent. These exclusion factors are related to mental capacity, a potential confounding factor in this study's results; however, counts of patients excluded for these reasons were not tracked during sample selection, and we are unable to report them. Fourth, the limited patient population available within the VA anticoagulation clinic setting of this study presents a significant limitation; the study sample consisted of veterans, most of whom are older males.

■■ Conclusions
The present study assessed anticoagulation knowledge of patients receiving warfarin therapy in a VA outpatient anticoagulation clinic using a validated instrument and found a pass rate of 74.1%, much higher than reported previously in the literature. We found no statistically significant relationships between 3 measures of INR control and anticoagulation knowledge. However, this is the first report of the relationship between INR control and anticoagulation knowledge as assessed by the AKA questionnaire, and it is possible that this assessment instrument, although previously validated, was not sufficiently sensitive in detecting clinically important warfarin knowledge. The frequently missed questions indicate potential areas for improvement in patient education. Re-evaluation of the current educational techniques is underway for identification of areas where improvements may be made.
have or changes in medications/diet. Therefore, both answers could be considered correct. These frequently missed questions indicate potential areas for improvement in patient education, including reinforcement of dietary guidelines for warfarin therapy as well as when it is appropriate to contact the clinic for questions. Both areas represent potential starting points for re-education of current patients and primary education for new patients seen in the clinic. At this point, re-evaluation of the current educational techniques is indicated for identification of areas where improvements may be made.
There were no statistically significant differences in demographic or clinical characteristics between pass and fail groups, including duration of treatment or indication of therapy, age, or gender. Data from the Spearman's rho analyses revealed no statistically significant correlations between warfarin knowledge and INR control. These results add to the existing literature that has found mixed results when assessing the relationship between patient warfarin knowledge and INR control. Tang et al. did find a small positive correlation between anticoagulation knowledge and the number of INR values within target range, showing that 4% of variance in INR could be explained by anticoagulation knowledge. 10 However, Davis et al. showed no significant association between knowledge or education and the proportion of INRs within the therapeutic range. 12 Our study revealed a higher pass rate of 74.1% as compared with pass rates reported previously in the literature, but it is possible that the AKA questionnaire was not sufficiently sensitive in detecting warfarin knowledge that is clinically important in the 3 measures of INR control.

Limitations
First, the collection of survey data from patients was not standardized. Patients could complete the knowledge test in the clinic, take it home and return it by mail, or return it at their next scheduled appointment. Fifteen patients (8.1%) completed the questionnaire at the facility; the other 171 patients (92.4%) completed the questionnaire outside of the facility. Although patients were expected to complete the questionnaire independently regardless of the site of completion, there was no way to prevent patients from eliciting assistance from various resources to help them complete the questionnaire. This problem may have contributed to an inflated pass rate in this study. Second, 66 respondents (35.7%) left at least 1 question unanswered. Of the 66 respondents with incomplete questionnaires, 12 left more than 4 unanswered questions, 3 missed entire pages, and 2 failed to complete the questionnaire. Because unanswered questions were considered incorrect answers, the latter 5 patients received a failing score. This decision may have contributed to cases that were judged as knowledge failures who would have achieved pass scores if all of the questions had 16