Any given month, Health Canada
issues dozens of alerts, warnings and recalls for a
growing number of products. The new warnings flood your
in-trays, as you juggle keeping on top of the latest
research with your top priority: seeing patients. There
are still only 24 hours in a day, so it's understandable
that you can't take it all in. In the US, the picture
is as grim. There, when the FDA really wants to cut
through the information overload and get doctors' attention,
they print a warning in an ominous black frame on the
drug's packaging, describing its risks and outlining
specific precautions for its use. Yet even these black
box warnings (BBWs) are widely ignored by US docs, according
to a giant survey of 930,000 American ambulatory care
patients.
BLACK
BOX MEDICINE
Researchers from the Department of Ambu-latory Health
and Prevention (DACP), which is co-sponsored by Harvard
Medical School, looked at the automated claims data
of these patients from January 1999 to June 2001. They
found that no less than 42% were prescribed a drug carrying
a BBW. "In ambulatory care settings, approximately 1.4
billion prescriptions are written per year," says lead
author Dr Anita Wagner, assistant professor with the
DACP. "This study tells us that these drugs are prescribed
often and that in some categories, prescribing is inconsistent
with the warnings." The results are reported online
in the November 18, 2005 issue of Pharmacoepidemiology
and Drug Safety.
A more detailed analysis considered
19 common black box drugs and how they were prescribed
in 217,000 patients. These drugs fell into three categories:
those that require laboratory testing of the patient;
those that could interact dangerously with other medicines;
and those that shouldn't be taken during pregnancy.
It seems doctors attach very different
levels of significance to these categories. Noncompliance
was most impressive with drugs that require a single
lab test at the outset to ensure patients don't fall
into a contraindicated group. In these cases, fully
49.6% of patients were given the drug without the required
test. At the other end of the spectrum, physicians were
very diligent with drugs that aren't safe for pregnant
women. Of the 79,000 such prescriptions written for
women of childbearing age, a mere 95 (0.3%) may have
occurred during pregnancy.
Clearly not all black boxes are
equally black in the eyes of the average prescriber.
Dr Wagner hints that the BBW's impact may be diluted
by overuse. "We need several things to improve the effectiveness
of the warnings: to be clear about the magnitude of
risk that justifies a BBW and the evidence that underlies
a recommendation and to communicate these warnings clearly
to both clinicians and patients."
THE
ONUS IS ON YOU
Here in Canada, the Therapeutic Products Directorate,
the Biologics and Genetic Therapies Directorate, and
the Marketed Health Products Directorate (MHPD) each
regularly post safety alerts and notices. In some cases,
the manufacturer is even required to send a flyer to
your office. But in the end, the ball's in your court.
"It's the physician's responsibility to keep abreast
of the latest drug safety information," says Jirina
Vlk of the MHPD.
The reality is that flyers always
seem to make their way to the recycling bin unread,
so how are Canadian docs getting the news they need
to know? We don't have any clear cut data, but a fascinating
case study related in the November 22 issue of the CMAJ
may provide a few clues.
In 1998, Health Canada approved
Diane-35 as a second-line treatment of severe acne.
From the mid-80s to mid-90s, the drug was marketed as
both an oral contraceptive and acne remedy in Europe,
Latin America and Australasia. Canada's laws on drug
advertising, which forbid mention of a drug's purpose,
led to a campaign which simply pictured happy, healthy
and acne-free young women that encouraged patients to
ask their doctor about the drug. A few years later,
strong data revealed that women taking Diane-35 were
at increased risk of venous thromboembolism. So in April
2003, Health Canada asked the manufacturer to send out
a "Dear Health Professional" letter notifying doctors
that the drug increased clotting risks and "should not
be prescribed for the purpose of contraception alone."
A few months later, the CBC TV series Disclosure
featured interviews with Canadian doctors and patients
who believed Diane-35 was just a contraceptive —
and were using it as such.
UBC researchers tracked prescribing
rates in the province and found that nearly half of
the recipients of the drug had no evidence whatsoever
of acne. They also found that the warning letter, and
another warning published in the CMAJ, had no
significant influence on prescriptions of Diane-35.
The CBC show, by contrast, was followed by an immediate
sharp dip in the number of prescriptions. "Although
news reports are often castigated as alarmist or as
raising unrealistic treatment expectations," concluded
the authors, "accurate reporting can also help to build
a link between research evidence and practice."
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