Background: Although most cases of asthma begin in early childhood, many children with wheeze do not develop persistent asthma. Frank and colleagues studied a cohort of children (initially younger than five years) for up to 11 years to identify predictors for persistent asthma.
The Study: The study was conducted by postal surveys of families in two large general practices in Manchester, England. Surveys were sent in 1993, 1995, 1999, 2001, and 2004 to all families with children younger than 16 years registered with the practices. Reminders were sent to nonresponders after four and eight weeks. The questionnaire was based on international studies of asthma and allergy in children, but used parent-reported wheezing as the key marker for respiratory disease. Parents were asked to report any wheeze or whistling-type respirations in their children by four features: (1) being woken by wheeze at least once per week; (2) speech interrupted by wheeze; (3) exercise-induced wheeze; and (4) more than three attacks of wheeze in the previous year. Other data collected included the child's sex, age at entry to the study, history of hay fever or eczema, symptoms associated with wheeze, and family history of asthma.
Results: Results were reported for children younger than five years at baseline who had at least six years of follow-up data. Of the initial 1,281 children surveyed, 628 (49 percent) met these criteria. Overall, 380 (60.5 percent) children had no reported wheeze during the study. Transient wheeze was reported for 147 (23.4 percent) children. Persistent asthma was reported for 101 children; 54 had early-onset and 47 had late onset. Of the 201 children who had wheeze at baseline, 26.8 percent were classified as having persistent asthma.
In statistical analysis, only a history of atopic disorders (odds ratio [OR] = 4.44) and exercise-induced wheeze (OR = 3.94) were significantly associated with persistent asthma. Of the children with wheeze at baseline, 37.8 percent had an atopic history and 52.7 percent had exercise-induced wheeze.
Conclusion: The authors conclude that, although about one third of children younger than five years are reported to have experienced wheeze in the previous year, only about one in four children with wheeze develop persistent asthma. If a preschool child with wheeze has neither exercise-induced symptoms nor a history of atopic disorders, the likelihood of persistent asthma is about 11 percent. If only one factor is present, the likelihood is about 17 percent. About one half of children with both factors develop persistent asthma.
editor's note: This study provides qualitative information for discussing prognosis with parents of young children with wheezing symptoms. The usefulness is limited by the lack of demographic information on the children studied. Although predominantly white, urban British general practices may include significant numbers of children of families originating in the Caribbean and Indian subcontinent, as well as immigrants from eastern and southern Europe. In particular, the odds ratios provided may not be applicable to black children.—a.d.w.