Background: Several factors such as colds, allergens or exercise can trigger wheeze in children. We studied whether persistence of wheeze in a clinical cohort depends on specific triggers.

Methods: We analysed data from children who visited respiratory outpatient clinics in Switzerland for possible asthma (Swiss Paediatric Airway Cohort). Information on triggers at baseline visit and wheeze during the subsequent 12 months was obtained from questionnaires. We studied the association between reported triggers at baseline?colds, allergens, exercise (alone and in combination)?and wheeze at follow-up using logistic regression adjusted for age, sex and wheeze frequency.

Results: Among 1086 children (mean age: 8 yrs, range 0-17; 61% male), 291 (27%) reported wheeze triggered by colds only, 75 (7%) by allergens only, 52 (5%) by exercise only, 380 (35%) by 2 of these triggers and 186 (17%) by all 3 triggers. For 102 (9%) children no specific trigger was reported. Overall, 57% of children (624) had wheeze at follow-up, whereby the proportion varied depending on the trigger: 36% of those with no specific trigger, 44% to 53% of those with 1 and 61% to 70% of those with 2 or 3 triggers. In the adjusted regression, those with wheeze triggered by allergens only (OR 2.0; 95%CI 1.1-3.7), exercise & infection (OR 1.9; 95%CI 1.1-3.4) and combinations of allergens with 1 or 2 other triggers (all OR >3.0) had an increased risk of persistent wheeze compared to those with no specific trigger.

Conclusions: This study confirms that children with wheeze triggered by several factors, particularly when associated with allergic triggers, have a higher risk of persistent wheeze compared to those with single triggers.

Funding: SNSF 320030_212519