TRAINING and EDUCATION
You Make the Call
Each month in “You Make the Call,” we’ll pick a challenging clinical question
submitted through the Consult-a-Colleague program and post the expert’s
response. But, what would YOU do? We’ll also pose a submitted question
and ask you to send your responses. See how your answer matches up to the
experts in the next print issue.
This month, Kenneth A. Bauer, MD, advises on the use of target-specific oral
anticoagulants in obese patients.
Clinical Dilemma:
Is it reasonable to use rivaroxaban as an antithrombotic drug in patients with very-high body mass index (>40 kg/m2)?
Experts Make the Call
Consult a Colleague is a service for ASH
members that helps facilitate the exchange of information between hematologists and their peers. ASH members
can seek consultation on clinical cases
from qualified experts in 11 categories:
Kenneth A. Bauer, MD
Professor of Medicine
Beth Israel Deaconess Medical Center
Harvard Medical School
• Anemias
• Hematopoietic cell
transplantation
• Hemoglobinopathies
• Hemostasis/thrombosis
• Lymphomas
• Lymphoproliferative disorders
• Leukemias
• Multiple myeloma & Waldenström
macgroglobulinemia
• Myeloproliferative Disorders
• Myelodysplastic Syndromes
• Thrombocytopenias
I have concerns about use of the
target-specific oral anticoagulants
in adults with normal renal function at the far extremes of body
weight. There were relatively few –
if any – such patients in the clinical trials evaluating their
safety and efficacy.
With total body water distribution of the agents, pharmacologic principles imply reduced drug levels in the
morbidly obese – potentially leading to loss of efficacy.
For those with very-low body weight, the opposite is true:
increased drug levels with total body water distribution of
the agents.
I am not certain where the weight cutoff is, but I
would have concerns if a patient weighs more than 300
pounds.
Obviously, the clinical situation comes into play when
deciding between warfarin and one of the newer targetspecific agents, as does the clinical scenario: Life-threatening pulmonary embolism in a morbidly obese patient
is a situation for which you would want the security of
warfarin and INR monitoring), as opposed to distal deepvein thrombosis (DVT, where there is controversy regarding the need to use an anticoagulant altogether, although I
generally do treat these for three months). For example, I
would not improvise by keeping a morbidly obese patient
on 15 mg bid rivaroxaban indefinitely.
Next Month’s Clinical Dilemma:
A 50-year-old patient who is currently on warfarin for a
second DVT in his leg was referred to me for consultation. At age 26, he had extensive right knee surgery to
repair a torn meniscus; subsequently, at age 42, he was
found to have unprovoked right-extremity DVT and
treated with warfarin for five years. The patient had a
heterozygous factor V Leiden abnormality and was also
found to have a lupus anticoagulant. He was off anticoagulation for three years and subsequentl y developed
38
ASH Clinical News
Assigned volunteer (“colleagues”) will
respond to inquiries within two business
days (either by email or phone).
Have a puzzling clinical dilemma?
Submit a question, and read more
about Consult-aColleague volunteers
at hematology.org/
Clinicians/Consult.
aspx or scan the QR
code.
an unprovoked DVT on the left side below the knee. He
restarted anticoagulation, but wishes to switch from
warfarin to an oral thrombin inhibitor. Should I have concerns about using an oral thrombin inhibitor – possibly
for another 35 years – in this patient?
How would you respond? Email us at ashclinicalnews@
hematology.org.
*If you have a request related to a
hematologic disorder not listed here, please
email your recommendation to ashconsult@
hematology.org so it can be considered for addition in the future.
DISCLAIMER: ASH does not recommend
or endorse any specific tests, physicians,
products, procedures, or opinions, and
disclaims any representation, warranty, or
guaranty as to the same. Reliance on any
information provided in this article is solely
at your own risk.
January 2015