Heightened bronchial hyperresponsiveness in the absence of heightened atopy in children with current wheezing and low income status.

BACKGROUND: Although global studies such as the International Study of Asthma and Allergies in Childhood (ISAAC) have provided valuable data on the prevalence of asthma in children in Latin America, there is little information on the relationship between asthma symptoms, pulmonary function, bronchial hyperresponsiveness (BHR) and atopy in the region.
METHODS: This study examined the relationship between self-reported wheezing in the past 12 months, pulmonary function, airway responsiveness and atopy in children from a low income population in a neighbourhood of Santiago, Chile. Two random samples (100 each) of children aged 13-14 years who participated in ISAAC phase I were selected according to whether or not they reported wheezing in the past 12 months. Spirometry, the methacholine bronchial challenge test and the prick test were performed in all individuals.
RESULTS: Children who reported current wheezing had significantly higher BHR to methacholine compared with those without wheezing (71.6% vs 52.6%; p = 0.007) and no significant difference was found in forced expiratory volume in 1 s (116.7 (12.3)% vs 120.3 (14.5%); p = 0.11). The prevalence of atopy was not significantly different between those children who reported wheezing compared with those who did not (44.2% vs 42.3%; p = 0.89). Multiple regression analysis showed that only BHR to methacholine (OR 2.72, 95% CI 1.25 to 4.13; p = 0.01) and maternal asthma (OR 3.1, 95% CI 1.2 to 8.3, p = 0.03) were significant risk factors for current wheezing.
CONCLUSIONS: Our results support previous findings suggesting that in adolescents from underprivileged populations, self-reported current wheezing is related to BHR but not to atopy.