Press Releases Saturday 25 September 1999
No 7213 Volume 319

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article and to tell your readers that they can read its full text on the
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the source BMJ article (URL's are given under titles).


(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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