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The
Asthma in Ashford study is a 'cohort' study.
This means that it involves a carefully chosen
group of people (a cohort) who are tracked over
a period of time. In this case the 'people'
are from Ashford and the 'time' is six years
and counting…….
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We
have had to be very careful about two aspects
in particular:
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1.
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Choosing
the right cohort. We wanted to select otherwise'
ordinary' people - in other words not people who
were especially likely or unlikely to develop
asthma. In this way any things we discover should
be relevant to most people. Since the factors
that cause asthma usually operate from early in
life we also needed to start with very young children.
We decided to begin with newly pregnant mothers.
We asked every woman going to their GP for antenatal
care in three general practices in Ashford if
they would like to take part. We explained in
detail what this would mean. Almost everyone (94%)
we asked agreed, and very few have changed their
minds since.
The babies of these women became the children
in the Asthma in Ashford study. |
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2.
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Cohort
studies like this work best if everybody stays
on board; otherwise you can never know whether
those who left were any 'different' from those
who stayed. Since we collected the cohort we have
spent a lot of effort in keeping track of all
the families. We have been quite successful at
this as you can see below - even though many families
have moved since we first made contact. |
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We
started with 642 newborn babies. We've attempted
to see all of them each year and so far, in
year 6, we are still in contact with 618 (96%).
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In the chart below you can see the numbers of
children we have seen at each stage
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