Asthma cases in childhood attributed to atopy in tropical area in Brazil / Asma infantil atribuida a atopia en la zona tropical de Brasil

OBJECTIVE: This study aimed to explore the association between asthma and atopy in a cohort of children living in a large urban center in Brazil. Atopy was defined by the presence of allergen-specific IgE in serum or by a positive skin prick test. METHODS: In a sample of 1 445 Brazilian children, the association between the prevalence of asthma, skin prick test positivity, and allergen-specific IgE in serum was investigated. RESULTS: The prevalence of asthma was 22.6 percent. The presence of serum allergen-specific IgE was frequent in asthmatics and nonasthmatics, and the prevalence of asthma increased only with levels of allergen-specific IgE > 3.5 kilounits/L. The proportion of asthma attributable to atopy was estimated to be 24.5 percent when atopy was defined by the presence of allergen-specific IgE. With a given level of specific IgE, no association between skin test reactivity and asthma was observed. Skin prick tests were less sensitive than specific IgE for detection of atopy. CONCLUSIONS: Most asthma cases in an urban underprivileged setting in Brazil were not attributable to atopy. This observation has important implications for understanding the risk factors for the asthma epidemic in Latin America.

OBJETIVO: Explorar la relación entre el asma y la atopia en una cohorte de niños que viven en un gran centro urbano de Brasil. En este estudio, se considera atopia la detección de IgE sérica específica de algún alérgeno o un resultado positivo a la prueba de punción cutánea. MÉTODOS: Se estudió la relación entre la prevalencia del asma, el resultado positivo a la prueba de punción cutánea y la detección de IgE sérica específica de algún alérgeno en una muestra de 1 445 niños brasileños. RESULTADOS: El asma registró una prevalencia de 22,6 por ciento. La presencia de IgE séricas específicas de alérgenos fue frecuente tanto en los asmáticos como en los no asmáticos, y la prevalencia del asma fue mayor solo cuando el valor detectado de la IgE específica del alérgeno era > 3,5 kilounidades/litro. Se calculó que la atopia definida como la detección de IgE específicas de alérgenos es responsable de 24,5 por ciento de los casos de asma. No se observó ninguna relación entre la reactividad a la prueba de punción cutánea y el asma en función de los valores de IgE específicas. La prueba de punción cutánea es menos sensible que la detección de IgE específicas en lo que respecta al diagnóstico de atopia. CONCLUSIONES: La mayoría de los casos de asma que se registran en entornos urbanos desfavorecidos de Brasil no son atribuibles a atopia. Esta observación tiene implicaciones importantes en lo que respecta a la comprensión de los factores de riesgo que predisponen a la epidemia de asma en América Latina.

Association of HRCT Findings Suggestive of Bronchiolitis Obliterans with Bronchial Hyperresponsiveness after Mycoplasma pneumoniae Pneumonia / 소아알레르기및호흡기학회지

PURPOSE: Bronchiolitis obliterans (BO) is an uncommon disease of the respiratory bronchioles and alveolar ducts that results in fibrosis and obliteration of the small airways. The causes of BO are diverse, but postinfectious BO is usually seen in children, especially after viral or Mycoplasma pneumoniae (M. pneumoniae) pneumonia. The aim of this study was to evaluate functional abnormalities such as bronchial hyperresponsiveness in the patients with High Resolution Computed Tomography (HRCT) findings suggestive of BO after M. pneumoniae pneumonia. METHODS: The diagnosis of M. pneumoniae pneumonia was made by a fourfold or higher rise in the antibody titers between acute and convalescent phase or a single very high titers (> or =1: 640) among children with clinical pneumonia. HRCT was checked in those with intermittent or chronic respiratory symptoms between one and two years after M. pneumoniae pneumonia. Eighteen patients with HRCT findings suggestive of BO (Group 1) and 24 patients with normal HRCT findings (Group 2) underwent methacholine bronchial challenge and skin prick testing. RESULTS: Mean FEV1 (% predicted) value of Group 1 (92.0%) was significantly lower than that of the Group 2. (101.1%) (P=0.048) The geometric mean of methacholine PC20 in Group 1 (8.5 mg/ mL) was significantly lower than that of the Group 2, (25.7 mg/mL) (P=0.008) with a higher frequency of bronchial hyperresponsiveness (PC20< 8 mg/mL) in Group 1 (38.8%) than in Group 2. (8.3%) (P=0.017) Prevalence of atopy was not different between Group 1 and Group 2, and mean FEV1 (% predicted) value and methacholine PC20 showed no significant difference according to the presence of atopy in either group. CONCLUSION: HRCT findings suggestive of BO after M. pneumoniae pneumonia were associated with functional abnormalities such as lower spirometric values and enhanced bronchial hyperresponsiveness.