From the Guidelines
Bronchiolitis is not necessarily a precursor for asthma, but there is a significant association between the two conditions, with children who experience severe bronchiolitis having a higher risk of developing recurrent wheezing and asthma later in childhood. This relationship appears to be influenced by both genetic predisposition and the severity of the initial bronchiolitis episode, as noted in studies such as 1. The connection likely involves inflammation and damage to developing airways during bronchiolitis, which may alter immune responses and airway function.
Key Considerations
- Children who experience severe bronchiolitis, particularly when caused by respiratory syncytial virus (RSV), are at a higher risk of developing recurrent wheezing and asthma later in childhood, as discussed in 1 and 1.
- The severity of the initial bronchiolitis episode and genetic predisposition play significant roles in the development of asthma, as suggested by 1.
- Many children who have bronchiolitis never develop asthma, and many people with asthma never had bronchiolitis as infants, highlighting the complexity of the relationship between the two conditions.
Recommendations for Parents and Clinicians
- Parents of children who have had bronchiolitis should monitor for persistent coughing, wheezing, or breathing difficulties after recovery, as these could indicate developing asthma, as recommended in 1.
- If these symptoms occur, especially with triggers like exercise, cold air, or allergens, medical evaluation is recommended for proper diagnosis and management, as emphasized in 1.
- Clinicians should be aware of the potential long-term sequelae of bronchiolitis, including the risk of developing asthma, and provide guidance to parents on monitoring and managing these conditions, as discussed in 1 and 1.
From the Research
Association between Bronchiolitis and Asthma
- Bronchiolitis, regardless of its etiology and severity, is associated with an increased risk of asthma, as shown in a population-based study 2.
- The study found that children who had bronchiolitis during the first 2 years of life had at least a 3-fold increased risk of recurrent wheezing and asthma at 2-4 years and an increased prevalence of asthma at ≥5 years of age.
- Another study supported the link between early life severe respiratory syncytial virus bronchiolitis and the physician diagnosis of asthma by school age, which continues into early adulthood 3.
Risk Factors and Causality
- The risk of asthma was similar in children with mild bronchiolitis as in those with hospitalized RSV-bronchiolitis, and was higher in children with hospitalized non-RSV-bronchiolitis 2.
- Whether viral bronchiolitis is causal or an early manifestation of future asthma remains uncertain, and may be dependent on host factors and virus-specific effects 3.
- Vitamin D status has emerged as a potential modifying factor for viral-induced wheeze and could potentially influence the development of asthma 3.
Types and Causes of Bronchiolitis
- Bronchiolitis can have several causes, including infection, toxic exposure, collagen vascular disease, post lung and stem cell transplant, and idiopathic etiology 4.
- Respiratory syncytial virus accounts for 60-80% of bronchiolitis presentations, and viral bronchiolitis is the most common cause of admission to hospital for infants in high-income countries 5.
- In adults, there is a wide spectrum of bronchiolar disorders, and most are chronic, with respiratory bronchiolitis being the most common form, usually related to cigarette smoking 6.