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Letters to the Editor
Factors Affecting Warfarin Related
Knowledge and INR Control of Patients
Attending Physicians and Pharmacists’
Managed Anticoagulation Clinics
Journal of Pharmacy Practice
25(1) 109-110
ª The Author(s) 2012
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DOI: 10.1177/0897190011431638
http://jpp.sagepub.com
Esin Beyan, MD1, Cengiz Beyan, MD2, and Songül Acar Vaizoglu, MD3
We have read with a great interest the article entitled ‘‘Factors
Affecting Warfarin Related Knowledge and INR Control of
Patients Attending Physicians and Pharmacists’ Managed
Anticoagulation Clinics’’ by Hasan et al which has been published online in Journal of Pharmacy Practice.1
We would like to comment on the article by referring to our
study on predisposing preventable factors among patients
admitted to the emergency department with bleeding due to
warfarin usage.2 Our study was performed on 114 cases who
were admitted to emergency service due to complaints of
bleeding due to warfarin usage. The sociodemographic characteristics, information on warfarin usage, and their bleeding history are collected by a structured questionnaire form. The mean
age of our patients was 66.65 + 13.57 years (mean + standard
deviation, 27-89 years, 82 cases 60 years) and 61 (53.5%) of
them were females.
In Hasan et al’s study, patients on warfarin scored an average of 66.5 + 36% for their knowledge on the mechanism of
action of warfarin, 42.9 + 44.9% for their knowledge on the
interaction between warfarin and alcohol, and 49.2 + 21.1%
for their knowledge on the side effects of warfarin. Fortyeight of the patients (42.1%) knew that they had to use this drug
under the regular follow-up of a physician and 43 (37.7%)
knew that during monitoring a laboratory test had to be done
while using the drug named warfarin in our study. Only 39
patients (34.2%) knew this drug may cause bleeding. It was
also surprising that only 9 of the patients were aware that there
might be an interaction with concomitant drugs and 1 knew that
this drug may be affected from the dietary factors.
In Hasan et al’s study, there was a significant difference
between patients’ age and knowledge on the mechanism of
action of warfarin (P ¼ .001), the interaction between warfarin
and alcohol (P ¼ .004), and the side effects of warfarin
(P ¼ .013). The correlation analysis showed that there was a
negative correlation between age and knowledge on the
mechanism of action of warfarin (P ¼ .001), the interaction
between warfarin and alcohol (P ¼ .001), and the side effects
of warfarin (P ¼ .001). There was no statistically significant
difference between the weekly warfarin doses used by the 82
cases who are 60 years and the 32 cases who are <60 years
(30.1 + 10.4 mg/week and 33.9 + 11.9 mg/week, respectively; P ¼ .107) in our study. In our study, although the weekly
dose of warfarin was lower, the duration between the onset of
warfarin and the time of bleeding is shorter and the bleeding
frequency within the first month of treatment is higher among
the 60 years age group (82 cases) when compared to patients
younger than 60 years (32 patients); no statistically significant
difference is found. Actually, in the literature, there are such
studies in which the relationship between the older age and
bleeding risk could not be shown like our study.3–5
According to the findings for their study, Hasan et al suggested that patients had satisfactory knowledge regarding the
mechanism of action of warfarin and poor knowledge on the
interaction between warfarin and alcohol as well as the side
effects of warfarin. But, our patients who were admitted to
the emergency service with bleeding have a big gap of
knowledge which invited bleeding. Most patients were using
drugs which are known to interact with warfarin metabolism
while using warfarin. Therefore, data given by Hasan et al on
the relationship between knowledge regarding the mechanism of action of warfarin and bleeding history of patients
should be reevaluated.
As a result, it is important developing a training program for
the related specialists and general practitioners who follow-up
such patients may have an effect on decreasing the morbidity
and mortality caused by warfarin-induced hemorrhages.
1
Department of Internal Medicine, Kecioren Education and Research Hospital,
Ankara, Turkey
2
Department of Hematology, Gulhane Military Medical Academy, Ankara,
Turkey
3
Department of Public Health, Hacettepe University, Faculty of Medicine,
Ankara, Turkey
Corresponding Author:
Cengiz Beyan, Department of Hematology, Gulhane Military Medical Academy,
Etlik, 06018 Ankara, Turkey
Email: [email protected]
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110
Journal of Pharmacy Practice 25(1)
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to
the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
References
1. Hasan SS, Shamala R, Syed IA, et al. Factors affecting warfarin
related knowledge and INR control of patients attending physicians
and pharmacists’ managed anticoagulation clinics [published online
ahead of print August 15, 2011]. J Pharm Pract. doi:10.1177/
0897190011415684.
2. Beyan E, Beyan C, Vaizoğlu SA. Predisposing preventable
factors in patients with bleeding due to warfarin usage: evaluation of 114 patients. Clin Appl Thromb Hemost. 2010;16(6):
684–687.
3. Lindh JD, Holm L, Dahl ML, et al. Incidence and predictors of
severe bleeding during warfarin treatment. J Thromb Thrombolysis. 2008;25(2):151–159.
4. Fihn SD, Callahan CM, Martin DC, et al. The risk for and severity
of bleeding complications in elderly patients treated with warfarin.
The National Consortium of Anticoagulation Clinics. Ann Intern
Med. 1996;124(11):970–979.
5. Copland M, Walker ID, Tait RC. Oral anticoagulation and hemorrhagic complications in an elderly population with atrial fibrillation.
Arch Intern Med. 2001;161(17):2125–2128.
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