Bronchial hyperresponsiveness decreases through childhood

• Published in: Respiratory medicine Vol. 106; no. 2; pp. 215 - 222
• Main Authors: Riiser, Amund, Hovland, Vegard, Mowinckel, Petter, Carlsen, Kai-Håkon, Carlsen, Karin Lødrup
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-02-2012; Elsevier; Elsevier Limited
• Subjects: Adolescent; Asthma; Biological and medical sciences; Bronchial Hyperreactivity - epidemiology; Bronchial Hyperreactivity - etiology; Bronchial Hyperreactivity - physiopathology; Bronchial hyperresponsiveness; Bronchial Provocation Tests - methods; Bronchoconstrictor Agents - administration & dosage; Child; Chronic obstructive pulmonary disease, asthma; Cohort Studies; Confidence intervals; Female; Forced Expiratory Volume - drug effects; Gender; Humans; Interviews as Topic; Logistic Models; Longitudinal; Male; Medical sciences; Methacholine Chloride - administration & dosage; Nitric oxide; Norway - epidemiology; Odds Ratio; Pneumology; Prevalence; Prospective Studies; Pulmonary/Respiratory; Risk Factors; Severity of Illness Index; Sex Distribution; Smooth muscle; Vital Capacity - drug effects; Norway; Bronchial hyperresponsiveness; Longitudinal; Child; Adolescent; Asthma; Human; Lung disease; Respiratory disease; Bronchus; Decrease; Bronchus disease; Obstructive pulmonary disease; Pneumology
• ISSN: 0954-6111; 1532-3064
• DOI: 10.1016/j.rmed.2011.09.013

Summary Limited knowledge exists about development of bronchial hyperresponsiveness (BHR) through adolescence. We aimed to assess changes in and risk factors for BHR in adolescence. From a Norwegian birth cohort 517 subjects underwent clinical examinations, structured interviews and methacholine challenges at age 10 and 16. BHR was divided into four categories: no BHR (cumulative methacholine dose required to reduce FEV1 by 20% (PD20 ) >16 μmol), borderline BHR (PD20 ≤16 and >8 μmol), mild to moderate BHR (PD20 ≤8 and >1 μmol), and severe BHR (PD20  ≤ 1 μmol). Logistic regression analysis was used to assess risk factors and possible confounders. The number of children with PD20 ≤ 8 decreased from 172 (33%) to 79 (15%) from age 10–16 ( p  < 0.001). Most children ( n  = 295, 57%) remained in the same BHR (category) from age 10–16 (50% with no BHR), whereas the majority 182 (82%) of the 222 children who changed BHR category, had decreased severity at age 16. PD20  ≤ 8 at age 10 was the major risk factor for PD20  ≤ 8 6 years later (odds ratio 6.3), without significant confounding effect (>25% change) of gender, active rhinitis, active asthma, height, FEV1 /FVC, or allergic sensitization. BHR decreased overall in severity through adolescence, was stable for the majority of children and only a minority (8%) had increased BHR from age 10 to 16. Mild to moderate and severe BHR at age 10 were major risk factors for PD20  ≤ 8 at 16 years and not modified by asthma or body size.