Blood Test May Predict Childhood Asthma Development

VIENNA — Simply relying on clinical symptoms is insufficient to predict which children with wheezing will develop asthma and respond to treatments. More objective tests like blood eosinophil counts are needed for early diagnosis and to avoid unnecessary medication use in children unlikely to develop asthma.

Sejal Saglani, MD, PhD, a professor of pediatric respiratory medicine at National Heart and Lung Institute, Imperial College, London, England, said that preschool wheezing has long-term adverse consequences through to adulthood. “We need to prevent that downward trajectory of low lung function,” she said, presenting the latest research in the field at the European Respiratory Society (ERS) 2024 International Congress.

Wheezing affects up to one third of all infants and preschool children, with one third developing asthma later in life. “It’s important to identify those kids because then we can treat them with the right medication,” Mariëlle W.H. Pijnenburg, MD, PhD, a pulmonary specialist at Erasmus University Rotterdam in Rotterdam, the Netherlands, told Medscape Medical News.

“We cannot just use clinical phenotype to decide what treatment a child should get. We need to run tests to identify the endotype of preschool wheeze and intervene appropriately,” Saglani added.

Eosinophilia as a Biomarker for Predicting Exacerbations and Steroid Responsiveness 

In a cluster analysis, Saglani and her colleagues classified preschool children with wheezing into two main subgroups: Those who experience frequent exacerbations and those who experience sporadic attacks. Frequent exacerbators were more likely to develop asthma, use asthma medications, and show signs of reduced lung function and airway inflammation, such as higher fractional exhaled nitric oxide and allergic sensitization. “Severe and frequent exacerbators are the kids that get in trouble,” she said. “They’re the ones we must identify at preschool age and really try to minimize their exacerbations.”

Research has shown that eosinophilia is a valuable biomarker in predicting both asthma exacerbations and responsiveness to inhaled corticosteroids. Children with elevated blood eosinophils are more likely to experience frequent and severe exacerbations. These children often demonstrate an inflammatory profile more responsive to corticosteroids, making eosinophilia a predictor of treatment success. Children with eosinophilia are also more likely to have underlying allergic sensitizations, which further supports the use of corticosteroids as part of their management strategy.

Saglani said a simple blood test can provide a window into the child’s inflammatory status, allowing physicians to make more targeted and personalized treatment plans.

Traditionally, identifying eosinophilia required venipuncture and laboratory analysis, which can be time consuming and impractical in a busy clinical setting. Saglani’s research group is developing a point-of-care test designed to quickly and efficiently measure blood eosinophil levels in children with asthma or wheezing symptoms from a finger-prick test. Preliminary data presented at the Congress show that children with higher eosinophil counts in the clinic were more likely to experience an asthma attack within 3 months.

“The problem is the majority of the children we see are either not atopic or do not have high blood eosinophils. What are we going to do with those?”

How to Treat Those Who Don’t Have Eosinophilia

Most children with wheezing are not atopic and do not exhibit eosinophilic inflammation, and these children may not respond as effectively to corticosteroids. How to treat them remains the “one-billion-dollar question,” Saglani said.

Respiratory syncytial virus and rhinovirus play a crucial role in triggering wheezing episodes in these children. Research has shown that viral-induced wheezing is a common feature in this phenotype, and repeated viral infections can lead to an increased severity and frequency of exacerbations. However, there are currently no effective antiviral therapies or vaccines for rhinovirus, which limits the ability to address the viral component of the disease directly.

Up to 50% of children with severe, recurrent wheezing also have bacterial pathogens like Moraxella catarrhalis and Haemophilus influenzae in their lower airways. For these children, addressing the bacterial infection is the best treatment option to mitigate the wheezing. “We now have something that we can target with antibiotics for those who don’t respond to corticosteroids,” Saglani said.

Pijnenburg told Medscape Medical News that this body of research is helping pulmonary specialists and general pediatricians navigate the complexity of childhood wheezing beyond phenotyping and symptoms. “We need to dive more deeply into those kids with preschool wheezing to see what’s happening in their lungs.”

Pijnenburg and Saglani reported no relevant financial relationships.

Manuela Callari is a freelance science journalist specializing in human and planetary health. Her words have been published in The Medical Republic, Rare Disease Advisor, The Guardian, MIT Technology Review, and others.