Asthma and allergy: the influence of overweight on the risk differs by sex in children

Being overweight affects the risk of asthma and allergy differently by gender in children, suggests a French study

This observation was made in the context of the study said the six cities, coordinated by Isabella Annesi-Maesano, INSERM U472 unit Villejuif (Val-de-Marne).

Several data have suggested a link between overweight and asthma, but most come from cross-sectional studies (which simply allow to find a relationship, not a relationship of cause and effect) explained Marie Dalitchamps, the U472, and colleagues.

They studied the association in 7781 children aged 9 to 11 years who were randomly recruited in 108 schools in six French cities (Bordeaux, Clermont-Ferrand, Créteil, Marseille, Reims, Strasbourg) between 1999 and 2001, pass evaluation of asthma and allergic diseases tests.

The researchers traced the weight gain of children during their growth using the body mass index (BMI, weight ratio of the square of height) to 10 years and weight index (PI, weight divided by the size of the cube) at birth (obtained according to the information contained in the health record). Depending on the value of these parameters, the children were classified into four groups.

In reviewing these data to take into account the possible influence of other parameters, the authors found that being overweight at birth is associated with the risk of allergic asthma significantly for girls only: it is multiplied by 2.6 in girls who have always been overweight (IP at birth and BMI at 10 years in the group of the most important values).

The overweight girls at birth are also at risk of allergic asthma doubled, even if they have lost weight to 10 years (IP at birth in the group of the most important values and BMI at 10 years in the group values lowest).

In contrast, the risk of allergic asthma in boys seems associated with a low PI at birth, it is accompanied or not an excessive weight gain during growth. The risk is doubled when BMI is 10 years in the group of the weak and almost tripled (OR = 2.8) for a BMI of 10 years in the group of the most important values.

In another analysis of data from the study of six cities, Chantal Raherison, University Hospital of Bordeaux, and colleagues evaluated the association between overweight and allergic diseases such as rhinitis or atopic dermatitis.

According to the results, only one rhino was significantly associated with overweight in girls, but not boys.

These results support the hypothesis that sex modulates the link between overweight and asthma and allergic diseases, probably involving hormonal factors, the researchers conclude.