Risk of Asthma in Infants and Toddlers that Wheeze
New Asthma NIH guidelines recommend early intervention in controlling inflammation associated with asthma. Inhaled steroids are the preferred controller medication in every age group. Pediatricians and family doctors are often hesitant to label a preschooler with the diagnosis of asthma out of concern that wheezing may not be permanent and, in fact, gone by school age. Studies have shown that at least 20% of these early wheezing children will have asthma and a risk of progressive loss of lung function as they age.
Is there a way to identify which children that wheeze in their first three years of life will eventually have asthma?
The answer is yes.
The Asthma Predictive Index (API) was first published by Castro-Rodriguez and others in the American Journal of Respiratory Care Medicine in 2000. Four years later, researcher Guilbert and others modified the index to include food allergy and published their findings in the Journal of Allergy and Clinical Immunology.
According to the modified API, a child has a positive index if there is:
1) A history of four or more episodes of wheezing. At least one or more of the episodes needs to be confirmed by a doctor.
2) The presence of at least one major and two minor criteria
- Having a parent with the diagnosis of asthma
- The child has eczema (diagnosed by a physician)
- The child is allergic to one or more pollens, molds, dust mites or pet dander (verified by allergy skin test or blood test)
- A history of wheezing without having a cold
- A blood test showing elevated eosinophils (4 or more percent of total white blood cells)
- Allergic sensitivity to milk, egg or peanut (by allergy skin test or blood test)
A positive API strongly suggests a child will have persistent or recurring wheezing (asthma). A negative API means asthma and persistent wheezing beyond age 5 is very unlikely.
You may ask, "What if my child has a negative API? What does this mean?"
There are many causes of wheezing which need to be considered in young children. Your doctor will take a complete history and do a physical exam. A chest x-ray and blood test may be ordered if the diagnosis is uncertain.
The majority of wheezing infants and toddlers fit into one of three categories according to the Tucson Children's Respiratory Study published by Martinez and Godfrey (Epidemiology of Wheezing in Infants and Children-2003).
1) Transient Early Wheezing (TEW): About 60% of wheezing infants belong to this group. Wheezing generally occurs early on in infancy. Major risk factors for TEW include maternal smoking during pregnancy, daycare attendance, having older siblings that are school-age, high exposure to house dust and other indoor allergens, and bottle propping in the bed or crib (thought to provoke gastro-esophageal reflux which may occur repeatedly). Children in this group no longer wheeze by school age. Allergy problems are not prevalent in the infant and family. They do not have asthma.
2) Nonatopic Wheezing (NAW): This category accounts for about 20% of early wheezing children. There is no association of parental allergy or asthma in this group. There is an association with premature delivery. Many of these children have a lower respiratory infection in their first year. Most of the children no longer wheeze by school age (as in TEW). There is a strong association of NAW with living in a developing country or an inner city of America.
3) Atopic Wheezing (AW): This group is highly associated with family history of allergy and asthma. They account for about 20% of early wheezing children and predictably have a positive API. They have normal lung function early on but it is reduced by school age (compared to the other groups).
Recent research has focused on the impact of inflammation in the first few years of having asthma. The 2007 NIH guidelines for asthma emphasize the importance of early diagnosis and appropriate treatment, aimed at achieving good control by reducing impairment and minimizing risk. Young children with poorly controlled asthma have a higher risk of reduced lung growth and severe asthma attacks. The API may be used by doctors to determine which children should be followed more closely and perhaps have more long-term inhaled steroids.
Bottom Line: Having a negative API or being a TEW or NAW is a good indicator of short term breathing problems. As the child gets older, the need for asthma medications will become diminished. Children with a positive API or considered to be an AW will likely need long term controllers and periodic assessment of their asthma control.