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 Doctors commonly prescribe daily low-dose aspirin after a heart
attack to reduce the risk of having a second cardiovascular event.
But about one in six patients stop taking their aspirin within three
years, the study authors note in Circulation.
“(Low-dose aspirin) makes the platelets in the blood less likely to
form blood clots, and this is especially useful in the coronary or
carotid arteries, where blood clots may lead to myocardial
infarctions and strokes,” lead author Dr. Johan Sundstrom told
Reuters Health by email.
“Millions of patients worldwide take aspirin on a daily basis and
might consider stopping at some time during their life. We performed
this study to help physicians and patients to make an informed
decision whether or not to stop aspirin use,” said Sundstrom, an
epidemiologist at Uppsala University.
To see if risk rises after a patient stops aspirin therapy,
Sundstrom’s team used nationwide medical and death registries to
identify patients over age 40 taking low-dose aspirin. In Sweden,
low-dose aspirin is available only by prescription, so the
researchers were also able to see who continued filling their
prescriptions between 2005 and 2009.
The researchers analyzed records for 601,527 patients who were
cancer-free and had taken at least 80 percent of their prescribed
aspirin doses during the first year of treatment. After excluding a
small proportion of patients whose medical records showed a reason
for stopping aspirin, such as surgery or a case of severe bleeding,
they found that about 15 percent of the full group had stopped
taking their aspirin after about three years.
At the end of the study period, there were a total of 62,690
cardiovascular events, defined as hospitalization for a heart attack
or stroke, or cardiovascular death.
“Patients who discontinued aspirin had a 37 percent higher rate of
cardiovascular events than those who continued," Sundstrom said.
That translates to one extra cardiovascular event each year among
every 74 patients who stopped taking aspirin.
The risk increased shortly after discontinuation, and did not appear
to diminish over time, he added. “Hence, adherence to low-dose
aspirin treatment in the absence of major surgery or bleeding is
likely an important treatment goal.”
The study wasn’t a controlled trial designed to prove that stopping
aspirin causes cardiovascular events. The researchers also didn’t
have access to information on other factors that could influence
risk, such as socioeconomic status, physical examination findings,
blood work or smoking status.
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“I think this gives clinicians more data to share with their
patients, however, it likely won’t change current practice patterns
for most providers because most already recommend low-dose aspirin
for their cardiovascular patients,” said Dr. Abha Khandelwal, a
cardiologist at Stanford University Medical Center in California who
wasn’t involved in the study.
The bigger issue is how to address the high discontinuation rate
noted in this study and learning how to overcome that will be very
valuable, she said in an email.
Khandelwal noted that there are several established reports
demonstrating lack of patient adherence to medications especially as
they get older, and their medication list grows longer.
“There are many reasons that can contribute to this, from cost of
medications, side effects, to confusion with a number of pills to
name a few,” she said.
At the Women’s Heart Health clinic at Stanford, adherence is good,
she noted. “This is partly due to the multidisciplinary approach
including internists, cardiologists, nurses, advanced care
providers, and behavioral psychologist who spend a considerable
amount of time on education, and identifying barriers to medication
adherence so we can work together with our motivated patient
population on overcoming them.”
Despite aspirin being an over-the-counter medication in the U.S., it
may have some side effects that one must weigh when prescribing,
such as damaging the lining of the stomach and increasing the risk
of bleeding, Khandelwal said.
“Therefore, patients need to continue a dialogue with their doctor
over time to determine whether they should continue on therapy. This
should especially be done prior to major surgery if they have had an
episode of severe bleeding that led to a hospitalization or resulted
in blood transfusions.”
SOURCE: http://bit.ly/2wlfeoq Circulation, online September 25,
2017.
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