Modifiable environmental factors predispose term infants to bronchiolitis but bronchiolitis itself predisposes to respiratory sequelae

Abstract

Introduction Viral bronchiolitis is a common lower respiratory tract infection in infants. Environmental and genetic factors can favor respiratory tract infections. Aim The aim of this study is to analyze risk factors for bronchiolitis and to investigate the predisposing factors for developing transient wheezing and asthma through a 6‐year follow‐up after hospitalization for bronchiolitis compared with a group of healthy controls that belonged to Piccolipiù cohort, who never had bronchiolitis. Methods We enrolled 645 infants hospitalized with bronchiolitis. A structured questionnaire was used to obtain demographic and clinical data. At 6 years of age, 370 cases and 183 controls were investigated for the presence of asthma by the structured questionnaire, for prick test and for spirometry, and were classified to asthmatic, transient wheezing, and no wheezing/no asthma. Results Breastfeeding was an independent protective factor (odds ratio [OR]: 0.3, 95% confidence interval [95% CI]: 0.2–0.4, p < 0.001) and tobacco smoke was a risk factor for the development of bronchiolitis (OR: 2.1, 95% CI: 1.4–3.1, p < 0.001). Analyzing follow‐up, bronchiolitis increased the risk of developing transient wheezing by 12.9 (95% CI: 6.3–26.1, p < 0.001) and of developing asthma by 4.6 (95% CI: 1.9–10.7, p < 0.001). A positive family history of atopy increased the risk of developing asthma by 3.1 (95% CI: 1.4–6.7, p = 0.005). Asthmatic patients had a lower % FEV1, a lower % flow‐volume curve (FVC), and a lower FEV1/FVC value, and they had more frequently positive skin prick test. Conclusion Bronchiolitis is influenced by environmental factors: tobacco smoke increases its risk and breastfeeding is a protective factor. At the end of 6 years of follow‐up, bronchiolitis is a significant risk factor to have pre‐school wheezing and asthma.

Environmental risk factors for respiratory infection and wheeze in young children: A multicentre birth cohort study

“…Our findings with respect to the beneficial effects of breastfeeding on reducing the risk of bronchiolitis are supported by large cohort studies from Italy 8 and Australia 9 . Given the established link between bronchiolitis and the subsequent asthma diagnosis in childhood, 26 this protective mechanism may explain the reduced risk of childhood asthma (5‐18 years) demonstrated by a large meta‐analysis in infants who were breastfed 27 .…”

“…Despite this, there is relatively limited data on the epidemiology and environmental risk factors for respiratory infection and wheeze in early childhood 1 . Suspected environmental risk factors include: daycare attendance 5–7 ; duration of breastfeeding 8,9 ; siblings 10,11 ; damp 12 ; environmental tobacco smoke (ETS) 13,14 ; house dust mites (HDM) 15 ; animals 16 ; traffic pollution 17–19 and solid fuel pollution 20 …”

UPDATE - 2022 Italian guidelines on the management of bronchiolitis in infants

“…Cleaning of solid surfaces using water and disinfectants or sodium hypochlorite is strongly supported (Evidence Quality: B; Recommendation Strength: Strong Recommendation). Exposure to tobacco smoke must be discouraged (Evidence Quality: B; Recommendation Strength: Strong Recommendation) [108,109].…”

“…Exclusive breastfeeding for at least six months should be encouraged to decrease the morbidity of respiratory infections (Evidence Quality: B; Recommendation Strength: Strong Recommendation) [1,[20][21][22][23][24][25][26][27][28][29][30][31][32][109][110][111].…”

“…• A gentle, superficial and reasonably frequent nasal aspiration, especially before feeding • Fractionated and frequent (2-3 hourly) meals asthma [122][123][124]. Hospitalization for bronchiolitis and the severity of the first episode are the main risk factors for developing subsequent wheezing [109]. However, it is unclear whether RSV infection is a causal factor, a marker of susceptibility to respiratory illness, or both.…”