Issue 24.
Evidence on Zanamivir (Relenza)
Bandolier this month pointed out that the National Institute of
Clinical Excellence (NICE) has issued guidance to the NHS concerning the use of zanamivir
in the treatment of influenza. It has also posted on its Internet site (www.nice.org.uk) a
summary of the evidence used in making its decision
(www.nice.org.k/appraisals/sum_evid.htm).
NICE conducted a widespread search, examined studies that were
randomised and compared zanamivir with placebo or current therapy in adults with influenza
A or B infections.
This left three studies, which had 813 patients given zanamivir and 775
given placebo. The high-risk population (patients with chronic respiratory, cardiovascular
or metabolic disorders, or who were immunocompromised or older than 65 years) numbered 217
patients.
About 70% of patients had influenza infection confirmed by laboratory
tests. The median reduction in the number of days of illness was one day for all patients.
It was 1.5 days (95% CHI to 2 days) for in-patients with confirmed influenza infection and
2.5 days in the high-risk group, though this was not statistically better than placebo.
Rates of complications of influenza infection were lower with zanamivir than with
placebo, for all patients (intention to treat analysis) and for those with influenza
infection and the high-risk group. The reduction in high-risk patients was not
significantly different from placebo. The number of patients needed to be treated to
prevent one complication of influenza infection was 14 (95% CI 9 to 33).
NICE have concluded that, based on this evidence, there is little advantage to be
gained in prescribing zanamivir. It is hard, on the evidence presented, to argue with
NICE’s conclusions on Relenza. For a fast track appraisal done in a very short time,
this is good stuff.
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Tumble drying of duvets may kill
asthma-associated mites
Hot tumble drying of comforters, duvets with fixed covers, using a
domestic clothes dryer is effective in killing the "great majority" of house
dust mites, according to researchers from New Zealand.
Writing in the August issue of the Journal of Allergy and Clinical
Immunology, Dr. Penny Fitzharris and colleagues at Wellington School of Medicine note
that according to the results of a recent study, tumble drying of blankets is effective in
killing mites. The researchers sought to determine whether this approach would also work
for synthetic duvets,"...widely used as bedding in New Zealand."
The investigators determined mite numbers and allergen levels in eight
duvets that had been used as bedding and had not been washed or dry-cleaned for at least 6
weeks. Each was tumbled in a domestic clothes dryer at the maximum heat setting for 1
hour, then left in a humid environment for about 20 hours "...to allow any live but
stunned mites to recover."
The "substantial numbers" of mites in the duvets were
significantly reduced by drying, but there was no significant reduction in mite allergen
levels, Dr. Fitzharris and colleagues found.
The researchers acknowledge that studies will have to be conducted to determine the
effects of drying on washed, wet duvets, but they conclude that "prolonged hot tumble
drying represents a convenient way of destroying mites in this type of bedding."
J Allergy Clin Immunol 1999;104:499-500.
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Explaining risks to patients
The general public have considerable problems with the risks that we
all face in daily life. The beef-on-the-bone argument, the discussions following the
recent train crashes point to considerable concerns about the sort of risk people face and
what sorts of risk are acceptable. The Paling perspective scale is an attempt to help with
a basic understanding of the levels of risk which we normally accept as reasonable and
those which we do not.
The idea is that various numerical or verbal representations of risk -
from 1 in 1 to 1 in 1,000,000,000 are rated between +6 and -6, like a pH scale. Like pH
also, the middle is comfortable neutral territory. In risk terms, the kinds of everyday
risks we live with in the home or with consumer products, like being injured by falls, or
gardening equipment, or by the television, fall in the region of +2 to +4.
At either end come the extremes. So at about -4 comes the risk of
anything happening to anyone in the whole world, and at -1 to -2 the risk of anything
happening to anyone in the UK. At the other extreme the odds of a child being born
to unmarried parents in the UK is +5.4, and the risk of dying from cancer by smoking 20
cigarettes a day for 20 years is +5.
Palings work comes with a plethora of examples, and with references and
source material. There is also a pull-out scale with some simple messages about what the
bottom line numbers translate into, ranging from paranoia paradise at -6 to -2, to just
take normal care at +1 to +2, change something at +4 to +5 and bye!!! at +5 to +6.
Reference: Singh AD, Paling J. Informed consent: putting risks into perspective. Surv
Ophthalmol 1997 42:83-6
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Under-diagnosis
of migraine in USA
Almost one third of Americans report symptoms of migraine, but have not
been diagnosed by a physician, according to the results of a new survey sponsored by the
National Headache Foundation. In addition, 58% of these subjects have never discussed
their symptoms with a physician.
"This survey shows that there are many people whose lives are
disrupted because of their headaches, and yet they are not seeking treatment,"
Suzanne Simons, National Headache Foundation Executive Director commented in a press
release. "It's clear that many patients don't mention their headaches to their
doctors and as a result are remaining undiagnosed and enduring unnecessary pain."
"We wanted to get our arms around the number of individuals with
under rated or untreated migraine," Simons told Reuters Health.
Too often, patients mention headache symptoms to their physicians as an
afterthought at the end of a visit, she continued. These individuals need to be encouraged
to make an appointment specifically for their headache symptoms, she pointed out.
As many new prescription and over-the-counter treatments for migraine
are now available, Simons said, it is very likely that most patients can be treated
effectively.
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