Asthma-like symptoms that begin during the first years of life are associated with deterioration in lung function and persistence of symptoms into adulthood. Identifying symptomatic children at a young age is important, because it can help physicians develop a strategy for early intervention to change the natural course of the disease. One such intervention may be the use of anti-inflammatory medications. Unfortunately, wheezy infants who develop asthma later in childhood coexist with a larger group of their peers who also wheeze in early life but whose symptoms subside by the early school years. Castro-Rodríguez and colleagues evaluated data to determine whether simple clinical indices could reliably predict the subsequent development of asthma in children with wheezing episodes in the first three years of life.
Patients were selected from the Tucson Children's Respiratory Study, a large, longitudinal assessment of respiratory illnesses in children. The eligible participants were 1,246 healthy newborns, enrolled at birth between 1980 and 1984, whose parents planned to use the pediatricians of a large health maintenance organization in Tucson, Ariz. Parents were asked to complete questionnaires about their child's history of respiratory conditions and general health at two, three, six, eight, 11 and 13 years of age. The issues specifically addressed were history of physician-diagnosed asthma, allergic rhinitis and eczema, as well as presence of wheezing apart from colds. Blood specimens were collected to test for eosinophilia.
Two separate indices were constructed for the study. The "stringent" index required early frequent wheezing during the first three years of life and either one major risk factor (eczema or parental history of asthma) or two of three minor risk factors (eosinophilia, wheezing apart from colds or allergic rhinitis). The "loose" index was defined as early wheezing and either one major risk factor or two minor risk factors.
Of the 1,002 children who had complete information for the stringent index, 63 (6.3 percent) had a positive index. Of the 986 children who had complete information for the loose index, 233 (23.6 percent) were positive. Children with a positive loose index for the prediction of asthma were 2.6 to 5.5 times more likely to have active asthma at some time during the school years than were children with a negative loose index. The risk of subsequent active asthma increased to 4.3 to 9.8 times more likely when the stringent index was used. The positive predictive values of the loose and stringent indexes were 59.1 and 76.6 percent, respectively, while the negative predictive values were 73.2 and 68.3 percent.
The authors conclude that deciding which of the two indexes to apply depends on the efficacy and potential side effects of any preventive measures recommended for at-risk patients. If a potential treatment has high efficacy but significant potential side effects, it should probably only be used in children with a very high risk of disease (i.e., those with a positive stringent index). Conversely, for a treatment regimen of modest efficacy but few or no side effects, applying a loose index for the prediction of asthma is reasonable.