International variations in bronchial responsiveness in children: Findings from ISAAC Phase Two

Gisela Büchele (1) , Jon Genuneit (1) , Gudrun Weinmayr (1) , Bengt Björkstén (2) , Ulrike Gehring (3) , Erika von Mutius (4) , Alfred Priftanji (5) , Renato Stein (6) , Emmanuel O Addo-Yobo (7) , Kostas N Priftis (8) , Jayant R Shah (9) , Francesco Forastiere (10) , Vija Svabe (11) , Julian Crane (12) , Wenche Nystad (13) , Luis Garcia-Marcos (14) , Yildiz Saraçlar (15) , Nuha El Sharif (16) , David P. Strachan (17)

1 Institute of Epidemiology
2 Institute of Environmental Medicine
3 Institute for Risk Assessment Sciences
4 Asthma and Allergy Department
5 Department of Allergology and Clinical Immunology
6 School of Medicine
7 Komfo Anokye Teaching Hospital
8 Alergology-Pulmonology
9 Jaslok Hospital & Research Centre
10 Rome E Health Authority
11 Children's Hospital
12 Department of Medicine
13 Division of Epidemiology
14 Pediatric Pulmonology and Allergy Units
15 Pediatric Allergy and Asthma Unit
16 Faculty of Public Health, Alquds University
17 Division of Community Health Sciences, St. George's

Summary Rationale: Bronchial responsiveness is an objectively measurable trait related to asthma. Its prevalence and association with asthma symptoms among children in many countries is unknown. Objectives: To investigate international variations in bronchial responsiveness (BR) and their associations with asthma symptoms and atopic sensitization. Methods: Bronchial challenge tests were conducted in 6,826 schoolchildren (aged 8-12 years) in 16 countries using hypertonic (4.5%) saline. FEV1 was measured at baseline and after inhalation for 0.5, 1, 2, 4, and 8 minutes. Bronchial responsiveness was analysed both as a dichotomous (bronchial hyperreactivity, BHR, at least 15% decline in FEV1) and as a continuous variable (time-response-slope, BR-slope, individual decline in FEV1 per log(min)). Results: Prevalence of wheeze last year ranged from 4.4% in Tirana (Albania) to 21.9% in Hawkes Bay (New Zealand) and of BHR from 2.1% in Tirana to 48% in Mumbai (India). The geometric mean BR-slope varied between 3.4%/log(min) in Tirana and 12.8%/log(min) in Mumbai and Rome (Italy). At the individual level, BHR was positively associated with wheeze during the past 12 months both in affluent countries (OR=3.6; 95%-CI: 2.7-5.0) and non-affluent countries (OR=3.0; 1.6-5.5). This association was more pronounced in atopic children. There was a correlation (ρ=0.64, p=0.002) between centre-specific mean BR-slope and wheeze prevalence in atopic, but not in non-atopic children. Conclusions: Bronchial responsiveness to saline in children varied considerably between countries. High rates of BR were not confined to affluent countries nor to centres with high prevalences of asthma symptoms. The association between wheeze and BHR at the individual level differed across centres and this heterogeneity can be largely explained by effect modification by atopy.

Mots clés: Medicine

Gisela Büchele, Jon Genuneit, Gudrun Weinmayr, Bengt Björkstén, Ulrike Gehring, et al.. International variations in bronchial responsiveness in children: Findings from ISAAC Phase Two. Pediatric Pulmonology, 2010, 45 (8), pp.796. ⟨10.1002/ppul.21259⟩. ⟨hal-00552427⟩