Keywords:
Atrial fibrillation - stroke - patient medication knowledge - warfarin - anticoagulants
Palavras-chave:
fibrilação atrial - acidente vascular cerebral - conhecimento do paciente sobre a
medicação - varfarina - anticoagulantes
Large population campaigns have been conducted in Brazil to improve knowledge about
the signs and symptoms of stroke and the importance of time to care. Along with receiving
the correct treatment, prevention by all means must be a priority to reduce the morbidity
and mortality of stroke.
Atrial fibrillation (AF) is a supraventricular arrhythmia that leads to a total disorganization
of atrial electrical activity, impairing the atrium's contraction capacity and inhibiting
the sinus node[1]. Stroke is the main complication of AF. At least one in five strokes is associated
with AF, and thromboembolic strokes in patients with AF are usually more severe and
incapacitating than in patients without AF[2],[3]. More than 100,000 deaths due to stroke are registered annually in Brazil[4]. Stroke is also one of the main causes of death and is the major cause of disability
in Brazil and in the world[2],[5],[6],[7].
Chronic therapy with oral anticoagulant drugs plays a crucial role in AF treatment
by significantly avoiding the risk of thromboembolic stroke, although it brings a
risk of intracerebral, or other hemorrhage[8]. Warfarin remains the most frequent oral anticoagulant prescribed in Brazil due
to its efficiency and low cost[6],[9],[10],[11].
Risk stratification of thromboembolic events helps identify which patients have a
stroke risk, and this clarifies the anticoagulant therapy[12]. Although the congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus,
stroke, vascular disease, age 65-74 years, sex category (CHA2DS2 VASc)[13] score has been proposed by vascular physicians, the congestive heart failure, hypertension,
age ≥ 75 years, diabetes mellitus, stroke (CHADS2) score is one of the main scales used for thromboembolic risk evaluation in patients
with AF by nonspecialists[6],[14],[15]. Treatment success in AF is highly correlated with patients' understanding about
their condition and therapy complications. Prevention of cerebrovascular diseases
must be one of the priorities in patient education, as the layperson's recognition
of its signs and symptoms remains poor[16],[17],[18].
We aimed to evaluate patients' knowledge about antithrombotic therapy in AF. We also
evaluated whether the therapeutic orientation received by the patient correlated with
the CHADS2 score.
METHODS
A cross-sectional study was conducted in a Brazilian Public University Hospital from
September 2015 to May 2016. A total of 150 outpatients were interviewed, seven of
whom did not meet the inclusion criterion. They were recruited from neurology and
cardiology clinics. The inclusion criterion was patients who had been assisted by
physicians at least once after receiving the diagnosis of AF. The study excluded patients
with cognition impairment reported by caregivers, and those who did not sign the consent
form.
A questionnaire with seven questions related to AF disease and its treatment was applied
to the participants. Question 1 was about the patient's identification (age and gender).
Question 2 asked if the patient had attended at least one medical appointment after
receiving the diagnosis of AF. If the answer was 'yes' we continued with the next
five questions. Question 3: “What is the treatment suggested by your doctor?” Question
4: “Did someone explain to you the risks in case of nonadherence to the anticoagulant
treatment?” Question 5: “If so, do you know what those risks are?” Question 6: “Have
you ever had a stroke?” Finally, question 7 asked about information used to calculate
the CHADS2 risk score ([Table 1]). For better accuracy, we asked what the medications in use were.
Table 1
CHADS2 score for thromboembolic risk stratification.
|
ABBREVIATION
|
RISK FACTOR
|
POINTS
|
|
C
|
Congestive heart failure
|
1
|
|
H
|
Hypertension
|
1
|
|
A
|
Age ≥ 75
|
1
|
|
D
|
Diabetes mellitus
|
1
|
|
S2
|
Prior stroke or transient ischemic attack
|
2
|
CHADS2 ≥ 2 indicates treatment with anticoagulation.
We classified the patients as “with basic knowledge” and “without basic knowledge”
according to what the authors expected patients would answer as complications of nonadherence
to antithrombotic therapy (question 5). Therefore, answers such as “stroke”, “thrombus
formation”, “hypercoagulability”, “embolic situations” or other vascular complications
were considered as correct in connection with risks (group A). The only vascular exception
was myocardial infarction or heart attack. Different answers not involving a vascular
system were considered “without basic knowledge” about antithrombotic therapy (group
B).
Data analysis
Data were analyzed with Software R (R Core Team, 2015; version 3.2.3). Data description was made through absolute and relative frequencies, means and standard
deviations. Fisher's Exact Test was used to correlate variables from questions 4 and
5 and the Difference Between Two Proportions Test, which indicates the probability
of a correct decision based on the alternate hypothesis, was applied on data from
question 3. The significance level considered was p < 0.05.
Ethical aspects
The study was approved by the Human Research Ethics Committee (protocol 1.207.053),
in agreement with Brazilian National Commission for Ethics in Research.
RESULTS
A total of 150 patients from Brazil's Public Health System were initially interviewed.
Seven patients answered “NO” to question 2 and did not follow through on the questionnaire.
They were excluded from the statistical analysis and results.
The mean age was 67 ± 10.65 years old (about one third of patients were < 65 years;
one third ≥ 65 and ≤ 74 years; and one third ≥ 75 years). Gender distribution was
approximately 1:1. In total, 131 (91.6%) were on anticoagulation therapy with warfarin,
and the rest were using antiplatelet agents ([Table 2]). No-one was using a non-vitamin K antagonist oral anticoagulant.
Table 2
Sample characteristics (%).
|
Variable
|
Total
|
With basic knowledge
|
Without basic knowledge
|
|
n
|
%
|
n
|
%
|
n
|
%
|
|
Female
|
75
|
52.4
|
37
|
49.3
|
38
|
50.7
|
|
Male
|
68
|
47.6
|
30
|
44.1
|
38
|
55.9
|
|
Age < 65 years
|
52
|
36.4
|
31
|
59.6
|
21
|
40.4
|
|
65 ≥ age ≤ 74 years
|
45
|
31.4
|
20
|
44.4
|
25
|
55.6
|
|
Age ≥ 75 years
|
46
|
32.2
|
16
|
34.8
|
30
|
65.2
|
|
Anticoagulation
|
131
|
91.6
|
64
|
48.9
|
67
|
51.1
|
|
No anticoagulation
|
12
|
8.4
|
3
|
25.0
|
9
|
75.0
|
|
CHADS2 < 2
|
23
|
16.0
|
11
|
47.8
|
12
|
52.2
|
|
CHADS2 ≥ 2
|
120
|
84.0
|
56
|
46.7
|
64
|
53.3
|
|
Previous stroke
|
42
|
29.4
|
25
|
59.5
|
17
|
40.5
|
|
No previous stroke
|
101
|
70.6
|
42
|
41.6
|
59
|
58.4
|
|
Previous orientation
|
91
|
63.6
|
63
|
69.2
|
28
|
30.8
|
|
No orientation
|
52
|
36.4
|
4
|
7.7
|
48
|
92.3
|
n: number of patients; %: percentage of patients; CHADS2: congestive heart failure,
hypertension, age ≥ 75 years, diabetes mellitus, stroke.
Ninety-one (63.6%) patients felt they were informed about the risks of lack of adherence
to the treatment (question 4), but when asked to identify what those risks were, only
37 (25.9%) identified “stroke”. Fifty-four (37.7%) patients said they didn't know
of any risk; 20 (14.0%) identified “blood thickening”; 16 (11.2%) identified other
vascular complications such as “thrombosis” and “pulmonary thromboembolism”; 14 (9.8%)
identified “thrombus formation”, “hypercoagulability” or “embolic situations” and
2 (1.4%) identified “death”. No one identified hemorrhagic stroke ([Figure]).
Figure Patients' knowledge
According to question 5, 67 (46.9%) patients were included in group A (with basic
knowledge) and 76 (53.1%) patients were included in group B (without basic knowledge).
Among the 91 patients who had been informed about the risks, 63 (69.2%) showed a basic
knowledge (group A) and 28 (30.8%) did not (group B). Thirty-five (38.4%) identified
“stroke” as a risk factor; 15 (16,5%) identified other vascular complications; 13
(14.3%) identified “thrombus formation”, “hypercoagulability” or “embolic situations”;
16 (17.6%) identified “blood thickening”; 11 (12.1%) said they did not know, and 1
(1.1%) identified “death” as a risk factor.
On the other hand, among the 52 patients who said they had never been informed about
the risks, 4 (7.7%) showed a basic knowledge and 48 (92.3%) did not. Two (3.9%) of
them identified stroke as a risk; 1 (1.9%) identified other vascular complications;
1 (1.9%) identified “thrombus formation”, “hypercoagulability” or “embolic situations”;
4 (7.7%) identified “blood thickening”; 43 (82.7%) said they did not know and 1 (1.9%)
identified “death”. The correlation between the variables “had been informed” and
“not had been informed” was statistically significant (p < 0.0001).
Forty-two (29.4%) patients had a previous history of stroke, 27 (64.3%) of whom were
women. Among these 42 patients who had already had a stroke, 16 (38.0%) identified
stroke as a complication from AF in the case of treatment nonadherence and 26 (62.0%)
did not.
Of all the patients with CHADS2 ≥ 2, 109 (90.8%) were on anticoagulation and 11 (9.2%) were taking antiplatelet agents.
Of 23 patients with CHADS2 < 2, 22 (95.7%) were on anticoagulation and 1 (4.3%) was taking an antiplatelet agent.
DISCUSSION
According to Hobbs et al.[2], the worldwide incidence of AF is 1% to 2% of the total population. Although the
incidence is higher among men, the morbidity and mortality associated with the illness
is higher in women[12],[19],[21]. There were no statistical differences in sex in our sample. The patients' ages
were also equivalent to the mean average in other studies.
Our patients showed a good correlation of the CHADS2 score with treatment. Of the patients who were on anticoagulation, only 25.9% identified
stroke as a risk of nonadherence to AF anticoagulant treatment. This alarming number
shows us why patients with AF continue to frequently be seen in stroke units, even
in the face of a well-known primary risk[21],[22]. The crucial role of anticoagulation and adherence to therapy in AF should be as
evident for patients as it is to physicians. The level of information should be as
clear as possible. Considering the risks of anticoagulation therapy, mainly of warfarin,
both types of stroke must be addressed.
An interesting point was that no patient mentioned hemorrhagic stroke or any other
hemorrhagic complication of anticoagulation. Although there was no specific question
about this, it was expected that patients with full understanding about antithrombotic
therapy would mention those risks at some point. However, this result may be a bias
from interpretation of the questionnaire.
To improve communication with patients, we should try to understand their reality.
Warfarin is the only oral anticoagulant available in Brazil's Public Health System[23]. It is well known that warfarin has many food and drug interactions and demands
a strict and frequent control of the international normalized ratio (INR) to avoid
risks that are obstacles for optimal treatment[24],[25]. Therefore, the patients' education about the disease and its risks is essential
to improve adherence and reduce complications[26],[27],[28].
The alarming lack of knowledge about basic concepts of AF and stroke shown in this
study might also help explain the high rate of stroke incidence and recurrence. We
found that 62.1% of patients with a previous history of stroke had no knowledge about
stroke as a complication of AF. We cannot assume that this lack of knowledge is totally
explained by the negligence of medical assistants. Among the 67 patients categorized
in group A (with basic knowledge), 63 said they had received previous information
about the risks. However, more than two-thirds of the sample did not mention stroke
risk in any way, so we can assume that there was a problem in the communication. Inadequate
language and lack of effort in teaching the patients may be interrelated. A low socioeconomic
and educational level may also have contributed to the patients' poor comprehension,
which may be a limitation to the generalization of results. We did not evaluate this.
Anticoagulation therapy had been prescribed for the majority of patients with CHADS2 ≥ 2, but not for 11 of them. On the other hand, 22 of 23 patients with CHADS2 < 2 were on warfarin and only one patient was on antiplatelet therapy. We assume
that some patients had been recently hospitalized and could be under acute treatment
for AF, or that anticoagulation therapy was indicated or contraindicated because of
concomitant treatment of other pathologies that were not evaluated by this study[29],[30]. The CHADS2 is not the only determinant of anticoagulation. Overall, we found it to be a good
therapeutic indication.
The non-vitamin K antagonist oral anticoagulants are an alternative to stroke prevention
in patients with AF. The wider use of these may improve adherence by providing a better
quality of life and fewer drug and food interactions, but the risks of stroke and
the need for education will still remain a concern[9],[31]. In addition, since INR monitoring is not required, the patients' contact with health
care professionals may be less frequent, as well as the opportunities to receive effective
education.
Better approaches to achieving patient understanding should be considered. Educational
campaigns, teaching manuals and adequacy of language could be useful. The physician's
compliance with the use of anticoagulants can never be forgotten, irrespective of
which drug is administered. We reinforce this with our results.
