Secondary prevention of asthma in overweight/obese children by a combined dietary-behavioural-physical activity intervention

Overweight and obesity has reached epidemic proportions worldwide, with more
than one billion adults overweight - at least 300 million of them clinically
obese - and is a major contributor to the global burden of chronic disease and
disability. Increased consumption of more energy-dense, nutrient-poor foods
with high levels of sugar and saturated fats in combination with reduced
physical activity, have led to obesity rates that have risen three-fold since
1980. In the Netherlands, overweight is present in 13% of the boys and 14% of
girls. Previous research demonstrates an increased risk on the development of
asthma in overweight children. Obesity is related to more severe asthma. In
adults, there is evidence that interventions directed towards weight reduction
and physical exercise are of help in improving asthma symptoms, exacerbation
rate, lung function, and quality of life. Such studies have not been performed
in children. Effective weight reduction programs have been reported in
children.

The current proposal studies the efficacy of a multifactorial intervention with
weight reduction, behavioural therapy, and physical exercise on the severity
and control of overweight/obese children with asthma.
Also the underlying mechanism of these interventions will be studied. In
addition the maintenance of the treatment effect after the intervention is
studied.

A two year, open randomized follow-up control trial.

The control group (n=75) will receive standard usual care according to the
standards of the Dutch Society of General Practitioners (NHG) and the
Paediatric Pulmonology section of the Dutch Society of Paediatrics (NVK).

The intervention group (n=75) will be an active intervention group with a
multifaceted family-based, physical exercise, nutrition, and behavioural
intervention during 18 months.

The nature of the burden associated with participation consist of: the dietary
intervention, physical exercise and the behavioural intervention. The baseline
measurement and last visit (t=0 and t=18 months) includes: a venapunction, a
static lung function test (also measured at t=6 months), collecting of exhaled
breath condensate and filling in a quality of life questionnaire. The dynamic
lung function test will be performed at 0, 6, 12, 18 and 24 months. Weight,
heigth and BMI will be determined at the same moments. Every month the presence
and severity of symptoms will be determined with a questionnaire.

Children receive a balanced hypocaloric diet for 18 months. At 0, 1, 3, 6, 12,
and 18 months the subjects will visit a clinical dietician with paediatric
experience. Every two weeks, parents and children will report two days of
24-hour intake of food and drinks.

The subjects will visit a research nurse with behavioural intervention
experience at 0, 1, 3, 6, 12, and 18 months.

Children will attend the physical exercise program twice a week during the
first six months (100 minutes per week) and every other week for an additional
12 months (100 minutes twice per month). Children are also encouraged to
exercise 3 additional days at home per week. Children and parents will register
activities every two weeks in a diary.

There are no risks associated with participation. The intervention is
non-invasive. Other study measures are also non-invasive, except the
venapunction. The intervention could have beneficial effects for the study
population, because an improving body weight/BMI and physical exercise in these
obese children with asthma is expected, which probably will improve their
health status, quality of life, asthma control, and need for medication.