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(1) CAUTIOUS
EVIDENCE OF THIRD GENERATION
PILL LINK
TO INCREASE IN THROMBOEMBOLISM
(2) CAMELFORD
WATER CONTAMINATION DID LEAD
TO CEREBRAL
FUNCTION DAMAGE
(3) BREAST
MILK ONLY FOR FIRST FOUR MONTHS
HELPS PROTECT
AGAINST ASTHMA AND ATOPY
(1) CAUTIOUS EVIDENCE
OF THIRD GENERATION
PILL LINK TO INCREASE IN THROMBOEMBOLISM
(Admission for and mortality from
primary venous
thromboembolism in women of fertile
age in Denmark,
1977-95)
http://www.bmj.com/cgi/content/full/319/7213/820
(The third generation oral contraceptive
controversy)
http://www.bmj.com/cgi/content/full/319/7213/795
Researchers from Denmark in this week's
BMJ report the
findings of their study which show an
increase in admission
rates of women for venous thromboembolism.
They say that
this rise seems to correlate with the
increase in the use of third
generation oral contraceptives.
Dr Lene Mellemkjr from the Danish Cancer
Society and
colleagues investigated all admissions
(male and female) in
Denmark for people aged 15 - 49 years
between 1977-93
with a registration of pulmonary embolism,
deep venous
thrombosis and other embolotic or thrombotic
disorders.
They studied admission levels in the context
of the use of third
generation pills representing 0.2 per
cent of total use of oral
contraceptives in 1984; 17 per cent in
1988; 40 per cent in
1990 and 66 per cent in 1993.
They found that admission rates for primary
venous
thromboembolisms among women fluctuated
around 120 per
million person years during 1977-88, but
increased to about
140 per million person years during 1989-93.
For men, the
admission rates remained stable throughout
the period at a
rate similar to that for women in recent
years.
Mellemkjr et al cautiously interpret this
as support for the
hypothesis that third generation oral
contraceptives increase
the risk of venous thromboembolism to
a greater extent than
second generation oral contraceptives.
They say that the
increase in admissions, although small,
could not be explained
by changes in diagnostic procedures or
in the threshold for
admission, since no increase was seen
among men.
In a linked editorial, Dr Paul O'Brien
from Parkside Health
NHS Trust in London echoes Mellemkjr et
al's caution. He
says that the increased risk of venous
thrombosis with third
compared with second generation pills
is real but that it is
small in absolute terms, although greatest
in women starting to
take the pill [overall estimates from
the Medicines
Commission are 15 per 100,000 women per
year in second
generation pill users and 25 per 100,000
women on third
generation pills, which is smaller than
that associated with
pregnancy, which has been estimated at
60 cases per
100,000 pregnancies]. He also says that
the causation
implied in Mellemkjr et al's study requires
stronger evidence.
However, O'Brien also writes that four
previous well
designed studies found that third generation
pills had double
the risk of thrombosis of second generation
pills. He says that
these studies have been subjected to relentless
criticism for
being flawed but, he says, these criticisms
have failed to
explain the excess risk. He also says
that subsequent studies
have generally been of lower methodological
quality and have
had variable results . "In a $3bn world
contraceptive market
the stakes are high" writes O'Brien.
O'Brien believes that clinical evidence
indicates that second
generation contraceptives should be the
first choice for
women. He says that the potential benefits
of the less
androgenic (ie less prone to produce masculine
characteristics) third generation pills,
such as reduced acne,
are yet to be proved but, if present,
for some women these
benefits may outweigh the small extra
risk of thrombosis. He
concludes that "It is not that third generation
contraceptives
are unsafe, it is just that we have something
safer."
Contact:
Dr Paul O'Brien, Senior Clinical Medical
Officer in Clinical
Effectiveness, Services for Women, Parkside
Health NHS
Trust, St Charles Hospital, London
Email: PaulOBrien@care.prestel.co.uk
Dr Lene Mellemkjr, Research Fellow, Institute
of Cancer
Epidemiology, Danish Cancer Society, Copenhagen
Denmark
Email: lene@cancer.dk
(2) CAMELFORD WATER
CONTAMINATION DID LEAD
TO CEREBRAL FUNCTION DAMAGE
(Disturbance of cerebral function
in people exposed to
drinking water contaminated with
aluminium sulphate:
retrospective study of the Camelford
water incident)
http://www.bmj.com/cgi/content/full/319/7213/807
People who were exposed to the contaminated
water at
Camelford in Cornwall, suffered damage
to their cerebral
function, argue researchers in a paper
in this week's BMJ. Dr
Paul Altmann and colleagues say that the
damage they found
in the people studied was not due to anxiety
as had been
previously claimed and they call for further
research to be
undertaken in order to determine the longer
term prognosis
for the affected individuals. In July
1988 twenty tonnes of
aluminium sulphate were accidentally emptied
into a treated
water reservoir in Camelford. The reservoir
served around
20,000 people and two years after the
accident about 400
people were suffering from symptoms which
they believed to
be as a result of the incident. These
include loss of
concentration and short term memory, and
were initially
attributed to anxiety, say the authors.
The research team was made up of experts
from the Oxford
Radcliffe Hospitals, the Royal London
Hospital, Coventry
and Warwickshire Hospital, Priory Hospital
in Roehampton
and University College London Medical
School. They
studied 55 of the affected people in the
Camelford area along
with 15 of their siblings who had not
been exposed to the
contaminated water as a control.
The team assessed the study and control
groups through
various clinical and psychological tests
to determine the
medical condition and anxiety levels in
the affected people.
They found that there were several abnormalities
in people
exposed to aluminium and other contaminants
in the
Camelford incident. For example, they
found that their
psychomotor performance was poorer than
the team would
have expected based on the IQ of affected
individuals before
exposure. Altmann et al also found that
anxiety did not
influence the measures of cerebral function.
Dr Paul Altmann et al conclude: "Aluminium
sulphate
poisoning probably led to long term cerebral
impairment in
some people in Camelford."
Contact:
Dr Paul Altmann, Consultant Nephrologist,
Oxford Kidney
Unit, Oxford Radcliffe Hospital, Oxford
Email: paul.altmann@orh.anglox.nhs.uk
(3) BREAST MILK ONLY
FOR FIRST FOUR MONTHS
HELPS PROTECT AGAINST ASTHMA AND ATOPY
(Association between breast feeding
and asthma in 6 year old
children: findings of a prospective
birth cohort study)
http://www.bmj.com/cgi/content/full/319/7213/815
Delaying the introduction of milk other
than breast milk until a
child is at least four months of age may
protect against asthma
and atopy (a predisposition to various
allergic reactions) in
later childhood, say researchers from
Australia in this week's
BMJ. They claim that their findings provide
grounds for
public health interventions to optimise
breast feeding which
may help reduce the community burden of
childhood asthma.
Dr Wendy Oddy from the Institute for Child
Health Research
and colleagues from Western Australia,
report the findings of
their study of 2,187 children in Perth,
which followed their
progress from antenatal clinics to the
age of six years. They
found that there was a significant reduction
in the risk of
childhood asthma by the time they reached
this age, if they
had been exclusively breast fed for at
least four months after
they were born.
Oddy et al speculate that the protective
effect of breast
feeding may operate in a number of ways.
They also say that
it is the age at which other milk was
introduced into an infant's
diet rather than the duration of breast
feeding that seems to
be more important in the association with
asthma and atopy in
later childhood. However, the authors
conclude that they
cannot definitively reject the possibility
that it is breast feeding
itself that is of prime importance.
They say that further studies are required
to confirm the
benefits that they have found and to better
understand the
mechanisms involved, but that public health
interventions
promoting an increased duration of exclusive
breast feeding,
may help to reduce the morbidity and prevalence
of
childhood asthma.
Contact:
Dr Wendy Oddy, Senior Research Officer,
TVW Telethon
Institute for Child Health Research, West
Perth, Australia
Email: Wendyo@ichr.uwa.edu.au
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