KOALA Birth Cohort Study: home-visits at age 6-8 years.

The prevalence of allergic diseases, asthma, overweight and obesity has rapidly
increased during the past decades, especially in western countries and amongst
children. Besides genetic susceptibility, lifestyle and environmental factors,
such as diminished/altered microbial exposure, play an important role in the
etiology of allergies. Feeding and snacking practices and physical activity
have also changed and affect the balance between energy intake and expenditure.
Asthma is more prevalent in obese children, and this may be due to shared
biological, behavioural and environmental factors.
Within the KOALA Birth Cohort Study we have examined the possible role of
several lifestyle and environmental factors in the development of eczema,
wheeze, allergic sensitisation, overweight and obesity in the first two years
of life. Further follow-up will enable us to study the influence of these
factors on the development of other allergic diseases, such as childhood
asthma, the development of obesity and cardiopulmonary fitness, and
cardiovascular and metabolic risk factors for adult pulmonary and
cardiovascular diseases.

To examine the influence of genetic predisposition, genetic factors, infections
and lifestyle of mother and child in relation to 1) allergic diseases and
childhood astma;
2) childhood overweight and obesity; 3) cardiopulmonary fitness and
cardiovascular and metabolic parameters as risk factors for adult pulmonary and
cardiovascular diseases.

The KOALA Birth Cohort Study is a prospective observational birth cohort study.

This application addresses further follow-up of children participating in the
KOALA Birth Cohort Study, a prospective birth cohort.

Although the study design is an observational cohort study, the administration
of salbutamol to measure reversibility of bronchial obstruction can be seen as
a non-therapeutic intervention.
During the home-visit baseline lung function will be measured, subsequently 3
pufs of salbutamol 200 micrograms/puf aerosol will be administered. 15 minutes
after administration of the salbutamol lung function will be measured again to
determine the reversibility of obstruction.

The burden for the parents is to schedule an appointment with the research team
for a home visit and to prepare the child; to schedule and perform
self-measurements of blood pressure in the morning and evening for 3 days; to
collect stool samples; for those children who use inhalant therapy for asthma,
to consult the study physician (a paediatric pulmonologist) if needed and to
coach the child to pause medication, and for the children participating with
physical activity measurements, to help the children wear the accelerometer,
and to return the devices to the team at a second home visit. The parents need
not record blood pressure and physical activity measurements, since the devices
have an electronic memory.
The burden for the child is to cooperate with the measurements (blood
measurements twice daily for 3 days) and to wear the accelerometer for 5 days
(if selected).
There is a small risk that devices are lost are damaged during use, but the
participants are waived for loss or damage.

Participants using bronchodilating medication for asthma complaints are asked
to pause inhalant therapy. There is a small risk that airway complaints
increase, in which case the child and parents are instructed to restart the
therapy.

Risk of blood sampling are small and contained by adherence to the appropriate
protocols for infection prevention. Pain by venopunction is limited by the use
of a topical anaesthetic cream (EMLA).

Only a subgroup of children will be invited to the hospital (in case of any
doubt on the diagnosis asthma based on the lung function testing and reported
symptoms during the home-visit). At the hospital a histamine provocation test
will be performed. This test is used in the clinic daily and in almost all
patients with chronic pulmonary diseases. The histamine provocation test has
been examined and validated many times and research has shown that this test
can be used safely in this specific age category (6-8 years old children).




Benefits are limited to reporting of immediate measurements where clear
reference values exist (lung function, NO and blood pressure) and occasional
case finding and advice to consult a physician when extreme measurement values
are found (blood pressure above*systolic and ..diastolic, previously
undiagnosed asthma when aplying to the ATS/ERS criteria). Measurements where no
validated reference values exist or without therapeutic consequences are not
communicated to the parents, unless they ask explicitly for it.
Children receive a little gift (color plate, toy). Many parents have shown
interest in the scientific results of the KOALA study so far, indicating that
many feel related to the KOALA study as a group.