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01.12.2008 | Research article | Ausgabe 1/2008 Open Access

BMC Health Services Research 1/2008

Best strategies for patient education about anticoagulation with warfarin: a systematic review

BMC Health Services Research > Ausgabe 1/2008
James L Wofford, Megan D Wells, Sonal Singh
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The online version of this article (doi:10.​1186/​1472-6963-8-40) contains supplementary material, which is available to authorized users.

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The author(s) declare that they have no competing interests.

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Warfarin is a dangerous outpatient medication, by anyone's estimation. It is the second most common cause of adverse drug events in emergency rooms, and the overall risk of major bleeding averages 7–8% per year [1, 2]. Despite the risk, well-established indications for warfarin are increasing in prevalence with aging of the population [3, 4], and new indications for warfarin are regularly recommended [5, 6]. As a result, the proportion of elderly persons taking warfarin has risen to as high as 7% [7].
Increasing a patient's understanding about warfarin is a logical goal. Prior knowledge about warfarin has been associated with a decreased risk of bleeding [8]. Written and verbal information has been shown to improve control of the level of anticoagulation [9]. While past studies suggest that patient education may be associated with better clinical outcomes, doubts remain about the effectiveness of patient education strategies [1012]. As a result, systematic patient education regarding long-term warfarin is not universally implemented.
Our objectives were to (1) identify the published strategies (duration, timing, personnel requirements, content domains) for patient education regarding warfarin anticoagulation and (2) identify published instruments for measuring patient knowledge.


In March 2007, we searched MEDLINE using the MESH terms ("warfarin" or "anticoagulation") AND "patient education". We limited our search to articles published in the English language. We used the related articles link in PubMed and searched the references of identified citations for additional original articles. Similar search terms were used to search Google Scholar. As warfarin is by far the most commonly used oral anticoagulant, we did not seek articles related to other oral anticoagulants.
We sought articles that (a) were original research studies or descriptions of patient education programs that included information on the educational content and strategy related to anticoagulation with warfarin, or (b) contained instruments that measured patient knowledge. Exclusion criteria included studies conducted in pediatric populations, unrelated to patient education, lacking original data or an adequate program description, and those in which the educational effort was focused solely on patient self-testing. Because citations might be excluded for multiple reasons, we used this above mentioned sequence for excluding citations.
An initial search identified 206 citations. Two reviewers (JLW, MDW) reviewed titles and available abstracts to determine relevance to the stated objectives of identifying (1) the optimal educational content and delivery (duration, timing, personnel requirements), and (2) the optimal strategies for measuring patient knowledge. Full text articles were retrieved for citations that met our inclusion criteria and for those where inclusion/exclusion criteria were not determinable by the title and abstract. Two other citations were encountered during the process of reviewing articles that were deemed eligible, raising the number of eligible articles to 208.
A total of 154 citations were initially excluded because patients were of pediatric age (1.9%, 4), the article was not related to patient education (23.1%, 48), did not contain original data or inadequate program description (18.8%, 39), was focused solely on patient self-testing (1), was a duplicate citation (1.4%, 3), or the article was judged otherwise irrelevant (16.8%, 35), or no abstract was available (11.5%, 24) (Figure 1).
After exclusions, a total of 44 articles qualified for further review. Upon further review, an additional 12 articles were excluded because of inadequate program description, ultimately leaving a total of 32 articles for data extraction (Figure 1). We extracted data on clinical setting, study design, group size, content source, time and personnel involved; and created summary tables. Two reviewers (MDW, JLW) identified the educational topics covered in these reports. Among studies that tested patient knowledge, we extracted information on setting and study population, number and type of questions, and method of administration.


Thirteen articles had a description of the research methods or program that was adequate and consistent with our objectives of identifying the duration, timing and setting, and personnel requirements of the educational program (Table 1) [1325]. Five programs used a nurse or pharmacist (45%), four used a physician, and two studies used other personnel/vehicles (lay educators (1), videotapes (1)). The duration of the educational intervention ranged from one to ten sessions. Patient group size most often averaged three to five patients but ranged from as low as one patient to as much as eleven patients. While the majority of the educational efforts occurred in inpatient settings, most seemed relevant to contemporary outpatient settings.
Table 1
Patient Education Strategies Related to Warfarin and Anticoagulation
Citation Location Study Design
Stated Goal
Group Size
Personnel involved
Menendez-Jandula et al13 2005 Barcelona, Spain RCT
To prove the value of self-management on INR control and clinical outcomes
5–8 patients and option of having family member present
Specially trained nurse
2 sessions of 2 hours on consecutive days Based on German model
Koertke et al14 20051 Westphalia, Germany Program description
To describe the principles of a training course to learn INR self-management
Not more than 5 patients
Not stated
Welcome period Two phase (hospital, 6 months later) Average duration 3–4 hours (1.5 for theoretical and 1.5 for device handling)
Voller et al15 20041 Westphalia, Germany Program description
To evaluate the effects of a training program on patient knowledge
2–5 patients
Not stated
Two half day sessions 2–7 days apart. Patient logbook
Khan et al16 2004 Newcastle, U.K. RCT
To prove the value of education and self-monitoring on INR control and quality of life
2–3 patients
Led by physician
1 two hour educational session
Gadisseur et al17 2003 Leiden, Netherlands RCT
To examine effects of self-management on quality of life
4–5 patients
Specialized teams of physicians and nurses
3 weekly sessions of 90–120 minutes
Singla et al18 2003 Philadelphia, U.S. Cohort Survey
To examine effects of group education on knowledge
11 persons
Pharmacist or nurse
1 one hour session
Amruso19 2003 Tampa, U.S. Program description
To examine effects of group education on knowledge
Chain pharmacy pharmacist
Ongoing monthly appointments
Beyth et al20 2000 San Francisco, U.S. RCT
To prove the value of self-management
Lay educator
Specifically formatted workbook. Coaching on communication skills. Self monitoring
Morsdorf et al21 1999 Saarland, Germany Program description
To examine the efficiency of patient training for self-management
4–6 patients
Single MD\Single instructor
4 theoretical and 2–6 practical sessions Video assisted demonstrations
Foss et al22 1999 Denver, U.S. Program description
To describe the efficiencies of a high-volume anticoagulation clinic
Not more than 6 patients
Pharm D
1 hour slide presentation
Sawicki et al23 1999 Dusseldorf, Germany RCT
To prove effect of self management on accuracy of control and quality of life
3–6 patients
Physicians and nurses
3 consecutive weekly teaching sessions of 60 to 90 minutes in duration
Stone et al24 1989 Worcester, U.S. RCT
To examine the effect of videotape on knowledge
15 minute videotape compared with 25 minute nurse lecture
Scalley et al25 1979 San Antonio, U.S. Program description
To develop a program for patient education
Pharmacist or nurse
Average 30 minutes. Slide presentation and booklet. Checklist of learning objectives placed in patient's chart
Although twelve articles offered information about education content, the wording and lack of detail in the description made it too difficult to accurately assign categories of education topics and to compare articles with one another [2, 11, 12, 15, 19, 2224, 2629]. Nevertheless, we summarized the categories suggested by these studies and listed the potential topics for each category (Table 2).
Table 2
Topics for Education of the Anticoagulated Patient
Educational Topic
Basics of anticoagulation
Description of the coagulation system
Normal blood clotting compared with clotting of an anticoagulated patient
Warfarin – mechanism
Risk of bleeding versus – descriptive versus numerical
Risk of clotting – descriptive versus numerical
Complications of thromboemboli
Color and strength of tablets
What to do if dose missed
Accessing healthcare professionals
When to call the doctor
When to seek emergency care
Anticoagulation services
Basics of Vitamin K
Specific foods
Lab monitoring
Basics of the INR
Therapeutic INR range
Most recent INR Result
Interpretation of INR values
Frequency of INR determination
Medication interactions
OTC medications
Injury management and contraindicated activities
Signs of bleeding events (overdose)
Signs of thromboembolic events (underdose)
Management of minor bleeding events
Medical alert bracelet
Special situations – illness, travel, pregnancy, surgeries
Endocarditis prophylaxis
Dose adjustment
Home coagulometry
Diary/quality control record keeping
Relevant to our objective of identifying measures of patient knowledge, Table 3 shows the seventeen relevant citations [9, 11, 12, 15, 18, 24, 3040]. Five of the seventeen sites where the surveys were administered were located in anticoagulation clinics/centers. The number of patients included in these studies ranged from as low as 22 to as high as 530. The number of questions ranged from as few as 4 to as many as 28 questions, and were most often of multiple choice format. Three were self-administered, and two were completed over the telephone. Two citations [12, 32] described testing instruments along with formal testing of the validity and reliability of the instrument.
Table 3
Studies Testing Patient Knowledge Regarding Anticoagulation
Setting/Study population
Questions – Number and Type
Hu et al30 2006
Large urban teaching hospital 100 mechanical valve patients
20, True-False
Scripted telephone survey Trained medical student
Zeolla et al12 2006 OAK test
U.S., Recruited from 4 pharmacies and 2 clinics 122 volunteers
20, Multiple choice, Validity and reliability testing
Self administered Excluded illiterate patients 7th grade reading level
Roche-Nagle, Chambers31 2006
Dublin teaching hospital anticoagulation clinic 150 consecutive patients
8, Specific answers
Standardized interview
Davis et al11 2005
Two NYC anticoagulation clinics 52 patients
18, Multiple choice
Self administered Single visit Excluded low literacy patients
Briggs et al32 2005 AKA test
Two Chicago inner city, pharmacist-managed anticoagulation clinics 60 patients
28, Multiple choice, Validity and reliability testing
Self administered Excluded illiterate patients 7th grade reading level
Voller et al15 2004
Three German 3 teaching centers 76 patients
13, Multiple choice
Questions not available
Nadar et al33 2003
3 U.K. teaching hospital anticoagulation clinics 180 patients who attended the clinic > 5 times
9, Short answer
Language concordance, personal interview
Tang et al9 2003
1 Hong Kong anticoagulation clinic 56 patients months postdischarge
9, Dichotomous and open-ended
2 rehearsed pharmacy students Leading questions avoided Scoring details
Cheah et al34 2003
U.S. teaching hospital center 50 inpatients
10, Open-ended
Telephone survey
Singla et al18 2003
U.S. anticoagulation center 180 patients
4, Yes/No
Immediately after class
Wilson et al35 2003
U.S. urban university hospital anticoagulation clinic 65 patients
20, Short answer
Investigator interview one week post discharge. Instrument not available
Barcellona et al36 2002
Italian thrombosis center 216 patients taking warfarin for 6 months
6, Multiple choice
Waterman et al37 2001
U.S. managed care organization 530 patients
11, True-False or short answer
Telephone-based interview at enrollment
Wyness et al38 1990
U.S. university hospital vascular surgery unit 23 patients
Interview soliciting explanation
Before discharge, and 1 & 3 months after discharge Oral interview
Stone et al24 1989
Hospital-based anticoagulation clinic 22 patients
18, True-False
Rankin39 1979
University hospital cardiac rehabilitation unit 19 patients
14, Multiple choice
3–4 days later and 3 weeks later Investigator administered
Clark et al40 1972
U.S. university hospital, 45 patients
15, Multiple choice
Self administered


Patient education has long been thought to be useful for patients receiving long-term anticoagulation. Proposals have been periodically issued suggesting the content of the educational task [2, 23, 41]. However, inadequate attention to health education principles and educational program design have more often been the problem than have issues of content [29, 42]. Despite the practical value of making the patient as knowledgeable as possible, the best strategy for educating patients about anticoagulation is yet to be determined [10].
The variety of strategies shown in Table 1 likely reflect a varying amount of support and resources devoted to this patient education goal. Delegating these educational activities to midlevel practitioners, pharmacists, or designated nurses are strategies well supported by the our literature review. However, in any given clinical setting, local factors such reimbursement and available manpower may determine which health professional(s) is best responsible for managing a population of anticoagulated patients. The advent of warfarin self-monitoring with home coagulometers has sparked renewed interest in improving patient education related to anticoagulation [2, 13]. Government-supported efforts in Germany and Netherlands now devote a significant level of time and manpower to this educational task [21, 43]. However, most clinical settings in the U.S. and elsewhere, may not be able to match that level of support [15]. Because most anticoagulation management still takes place in the offices of clinicians [44, 45], strategies to provide education should be relevant to all clinical settings.
We also found much variability in the content areas reported by educational programs, to the degree that we could not accurately categorize educational domains, let alone make fair comparisons among programs. Some issues (manifestations of bleeding, INR monitoring, etc) were a component of most educational programs, while other issues (Vitamin K, pill color) were present only in a few. Our inability to summarize published efforts likely reflects an underreporting of details rather than extreme variability among programs. Nevertheless, our table of potential educational topics (Table 2) reflects a daunting agenda.
The testing of patient knowledge regarding warfarin and anticoagulation used a variety of instruments. Only two of the sixteen instruments – the Oral Anticoagulation Knowledge (OAK) instrument and the Anticoagulation Knowledge Assessment (AKA) – have been subject to any formal evaluation. The Oral Anticoagulation Knowledge (OAK) investigators evaluated construct and content validity, test-retest reliability, and internal consistency reliability [12]. The Anticoagulation Knowledge Assessment (AKA) investigators used the Rasch model in order to examine validity, and item and person reliability [32]. Both the OAK and AKA are reported to be written at the 7th grade reading level, but neither instrument has been validated in other clinical settings. The best strategy for measuring patient knowledge would depend, in part, on the content of the educational program, but standardization of the testing effort should be a realistic goal.
The limitations of our study deserve acknowledgement. While our study reflected a variety of different strategies for all aspects of the educational process, it is probable that noteworthy and innovative patient education efforts may not be reflected in the medical literature. Second, in reviewing these reports, it is often difficult to separate the management strategy from the educational strategy.
Despite the variability in the content and strategies of educational programs, several important issues should drive future efforts at patient education, in our opinion. Educational programs should focus on topics essential for patient safety, such as what to do when INR is high, rather than the minute details of anticoagulation that overburden the patient. Second, these programs would best be implemented with measures of effectiveness and improvement in patient knowledge, adherence and outcomes using validated instruments. Lastly, educational programs should attempt to maximize office efficiency by delegating this task to physician extenders, nurses, pharmacists, or perhaps an office-based computer.


Patient education is entering a new era where accountability in educational outcomes, interest in literacy/language barriers, and the importance of cost-effectiveness will influence the process of patient education. Prioritizing the educational content and using validated instruments for measuring the outcomes of patient education will be a necessary first step in improving anticoagulation outcomes. This systematic review should guide future efforts.


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