Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT01229787 |
| Other study ID # |
CIIRespiratory1 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
October 27, 2010 |
| Last updated |
October 27, 2010 |
| Start date |
January 2007 |
| Est. completion date |
December 2009 |
Study information
| Verified date |
July 2009 |
| Source |
Cyprus International Institute for Environment and Public Health |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
Cyprus: Cyprus National Bioethics Committee |
| Study type |
Observational
|
Clinical Trial Summary
Obesity has been recognized as a risk factors for developing asthma. In a cohort of 5384
children aged 15-17, we aim to:
1. To investigate the association of asthma prevalence at age 15-17 with body mass index
(BMI) at age 15-17 and BMI at age 11-12 years Part II
2. To investigate the association of BMI in adolescence and BMI at age 11-12 years with:
1. Prevalence of allergic sensitization
2. Lung function
3. Levels of airway inflammation at age 16-18 years
4. Severity of asthma
Secondly, to assess diet and physical activity involvement as effect modifiers in these
possible associations.
Description:
Cross-sectional studies in Northern America, Northern Europe and Asia indicate an increased
prevalence and severity of asthma in the obese whereas longitudinal studies have indicated
that increasing BMI is associated with increased risk of incident asthma in women. However,
the mechanisms through which where-by obesity increases the risk for asthma remain unclear.
There are only few studies from North America and Asia that suggested that obesity is
associated with increased skin test reactivity and atopic diseases and many more that
suggest obesity has no association with atopy. In adult asthmatics, it has also been shown
that both medical and surgical weight loss is consistently associated with dramatic
improvements in lung function, asthma symptoms, and medication usage. However, in children
no study has elaborated on the potential benefits of reducing weight.
Total fat intake has also been associated with the diagnosis of asthma. N-3 fatty acids have
been noted to inversely correlate with body fat, while levels of N-6 fatty acids correlated
positively with body fat. Increased dietary intake of N-3 fatty acid (such as
eicosapentaenoic acid) (mainly fish oils) has been generally associated with protection from
asthma, while intake of N-6 fatty acids (such as linoleic acid) may increase asthma risk,
although this remains controversial. Linoleic acid may act as a precursor of arachidonic
acid which subsequently serves as a precursor of 4-series leukotrienes that are highly
active mediators of inflammation.
There are only two studies that investigated the levels of exhaled nitric oxide (ENO) as
indicator of airway inflammation in relation with obesity and asthma. One study showed
significant increase of ENO with increasing BMI in healthy adults. However, the levels of
ENO and exhaled leukotriene B4 were recently found to be increased in lean and obese
asthmatic children but not related to their BMI's.
In Southern European countries, there are no representative epidemiological data on the
contribution of obesity to asthma burden. In this area of the world, there are also no
studies on the effect of important lifestyle factors including diet and physical activity on
the association of adiposity with asthma pathophysiology. In addition, no information exists
on levels of airways inflammation both in non-asthmatics and asthmatics subjects in relation
to body content in fat and the impact of weight reduction on airway inflammation.
In years 2001-2003, a national health survey was conducted in Cyprus focusing on nutrition
and physical fitness of all children aged 11-12 years (attending the 6th form of all primary
schools). With this project we proposed to approach this group of children in years
2007-2009 to investigate the following hypotheses:
AIMS:
The aims of the study are as follows:
Part I To investigate the association of asthma prevalence at age 15-17 with body mass index
(BMI) at age 15-17 and independently with BMI at age 11-12 years Part II
To investigate the association of BMI at age 16-18 and independently of BMI at age 11-12
years with:
1. Prevalence of allergic sensitization
2. Lung function
3. Levels of airway inflammation at age 16-18 years
4. Severity of asthma
Secondly, to assess diet and physical activity involvement as effect modifiers in these
possible associations.
PART I METHODOLOGY:
Study population Part I took place during the months of January 2007 to June 2007 and
children attending the 1st (15-16 years) and 2nd (16-17 years) classes in all public and
private Lyceia schools across the Republic of Cyprus were invited to participate. The
targeted population were 19849 children that participated in an earlier study in years
2001-3 and had amongst other assessments anthropometric measurements, assessment of
cardio-respiratory fitness and serum lipids taken at that time.
For the assessment of children's asthma status we used the Greek version of the ISAAC
(International Study of Asthma and Allergies in Childhood) core questionnaire supplemented
with questions relating to potential person-based risk factors such as the place of birth of
the child, ethnic origin of the parents, birth order, parental education level, parental
smoking, history of atopy in the immediate family (siblings and parents with a history of
asthma, eczema and or hay fever), personal uptake of smoking, pet ownership and place of
residence.
All participating students had also their weight, percentage body fat and Body Mass Index
(BMI) measured. The subjects' BMI had been classified as normal weight, overweight or obese
according to sex and age specific cut-offs (six months intervals), suggested by the
International Obesity Task Force (IOTF).
Compilation of Dataset
An effort to match subjects on the 2007 cross-sectional database with subjects on the
2001-2002 old cross-sectional database was carried out using various matching parameters. A
dataset of 5384 subjects was constructed with matched BMI values in 2007 (aged 15-17 years)
and in 2001-2003 (aged 11-12 years).
Statistical Analysis
Using answers to the basic questions for asthma and respiratory morbidity of the ISAAC
questionnaire the case definition was further refined to:
1. Active asthma: positive answers to questions on ever having asthma and current wheeze
and or night time cough unrelated to colds in the past 12 months
2. Inactive asthma: positive answer to question on ever having asthma and negative answers
to questions for current wheeze and night time cough unrelated to colds in the past 12
months
3. Respiratory symptoms without asthma: negative answer to question on ever having asthma
and positive answer(s) to questions on current wheeze and or night time cough unrelated
to colds in the past 12 months.
The associations between disease outcomes and obesity predictors (BMI z-score and body fat
%), were analyzed through univariate analysis and the odds ratio (OR) were calculated with
95% confidence intervals (CI). In addition to the univariate analysis, multiple logistic
regression was also performed to further investigate the associations of obesity predictors
and disease outcomes adjusting for confounders and stratifying by significant effect
modifiers. Statistical significance was set at P < 0.05.
