Phenotype from Birth to 1 Year: Implications for Asthma

The utility of determining a patient's asthma phenotype is a current research priority, since various phenotypes seem to respond differently to interventions and medication. Researchers have conducted the lion's share of research in older children and adults, and little information has been available about asthma phenotypes in infants. Researchers from a number of public health agencies in France took on the task of identifying phenotypes in infants. The results of their study, published in the journal PLoS One, indicate that early respiratory symptoms predict asthma at 1 year.

Healthcare providers, and parents identify wheezing in approximately 25% to 30% of infants. Its etiology is often difficult to trace, as environmental exposure (including parental smoking), and viral infection can cause wheezing. When wheezing is associated with asthma, it protects reduced respiratory function, and accelerated lung function decline in later life. For this reason, these researchers were eager to find factors that could predict asthma. A study strength is at the researchers looked at more than 18,000 infants over the course of their first year. They identifed 4 specific phenotypes:

• non-wheezers (no current wheezing symptoms at both 2 months and 1 year old)
• intermittent (current wheezing symptoms at 2 months but no wheezing at 1 year)
• persistent (current wheezing at 2 months and at 1 year)
• incident (no current wheezing at 2 months but wheezing at 1 year)

This study found that children who experienced nocturnal cough, signs of respiratory distress, and excess bronchial secretion, and whose symptoms continued to increase from age 2 months to 1 year, were at elevated risk for persistent wheezing.

They also linked maternal smoking with persistent wheezing, and incident wheezing at one year. They note that children born to women who smoke tend to have narrower airways than others. This may contribute to wheezing. A mother's history of hay fever, eczema or asthma also increase the likelihood of persistent wheezing in children.

Reference

Hallit S, Leynaert B, Delmas MC, et al. Wheezing phenotypes and risk factors in early life: The ELFE cohort. PLoS One. 2018;13(4):e0196711.