Factors associated with allergic rhinitis in children and adolescents from northern Mexico: International Study of Asthma and Allergies in Childhood Phase IIIB.

The epidemiology of allergic diseases has not been studied extensively in Mexico. The present study, based on the International Study of Asthma and Allergies in Childhood Phase IIIB survey, reports the prevalence of allergic rhinitis and the associated risk factors in the pediatric population in four cities in northern Mexico. Children (6-7 years old) and adolescents (13-14 years old) in public elementary and secondary schools were surveyed in 2002 and 2003. The subjects were chosen randomly from Ciudad Victoria, Mexicali, Monterrey, and Tijuana. The following categories were analyzed: occurrence of rhinitis symptoms (currently or in the last 12 months), rhinoconjunctivitis symptoms, a previous diagnosis of allergic rhinitis, and relevant environmental factors. Factors associated with rhinitis that were identified previously with the chi-squared test were analyzed using logistic regression. The number of valid questionnaires was 10,892 for schoolchildren and 12,299 for adolescents. In 6- to 7-year-old children, the following frequencies were determined: rhinitis (ever), 27.9%; current rhinitis, 24.2%; rhinoconjunctivitis, 9.2%; and diagnosis of allergic rhinitis, 5.5%. The corresponding frequencies in 13- to 14-year-old children were 33.3, 34.1, 18.4, and 3.8%. In both 6- to 7-year-old and 13- to 14-year-old children, all rhinitis items were associated with asthma symptoms, dermatitis symptoms, paracetamol consumption, and maternal smoking (odds ratio, >1; p < 0.05). The main risk factors associated with allergic rhinitis symptoms in children and adolescents from cities in northern Mexico were other allergic conditions, paracetamol consumption, and passive smoking.

Effect of obesity on bronchial hyperreactivity among Latino children.

BACKGROUND: The association between obesity and bronchial hyperreactivity (BHR) in children has not been fully demonstrated in cross-sectional or longitudinal studies, and no study has specifically addressed Latino children. METHODS: A cross-sectional study of 450 children (10-18 years) from public schools was conducted in Mexico city. Among this group, 260 met the study criteria (no chronic respiratory illnesses, including asthma and rhinitis; no acute respiratory infections; and no tobacco-exposure or endocrine or body dysmorphic disorders), and 229 performed reproducible pulmonary function and methacholine challenge tests and were fully analyzed. RESULTS: According to BMI percentiles, 40 were normal weight, 116 were obese, and 73 morbidly obese. Children in the morbidly obese group had significantly higher % FVC than those in the normal-weight group, and obese children had higher % PEF those in the morbidly obese and normal-weight groups. In the BHR methacholine challenge test, baseline FEV1 values among obese children were significantly lower than in the morbidly obese group. Using adjusted percentages for FEV1 , values were significantly lower among obese compared to morbidly obese children at metacholine concentrations of 0.25, 1, and 4 mg/ml. The proportion of positive BHR (PC20 ≤ 16 mg/ml) was higher in these two groups compared to normal-weight children (28.4%, 17.8%, and 12.5%, respectively), although differences were not significant. CONCLUSION: Our findings show that obesity by itself is not a sufficient condition to alter airway responsiveness to methacholine in a group of adolescents.