Severe intermittent wheezing in preschool children: a distinct phenotype.

BACKGROUND

Young children with wheezing predominantly with respiratory tract illnesses experience severe exacerbations separated by extended periods of wellness and may be described as having "severe intermittent wheezing," a diagnostic category not currently recognized in national guidelines.

OBJECTIVE

We sought to characterize a cohort of children with recurrent severe wheezing.

METHODS

A total of 238 children 12 to 59 months enrolled in the Acute Intervention Management Strategies trial were characterized through comprehensive allergy, asthma, environmental, and quality of life assessments.

RESULTS

Asthma symptoms over the period of the preceding year occurred at frequencies consistent with intermittent asthma, as 94.5% of children experienced activity limitation < or = 2 times per month. However, frequent severe exacerbations were common, because 71% experienced > or = 4 wheezing episodes over the period of the preceding year, 95% made at least 1 primary care visit, 52% missed school or daycare, 40% made an emergency department visit, and 8% were hospitalized for wheezing illnesses. Atopic features were common, including eczema (37%), aeroallergen sensitization (46.8%), and positive asthma predictive index (59.7%). Oral corticosteroid use in the previous year (59.7% of the cohort) identified a subgroup with more severe disease documented by a higher incidence of urgent care visits (P = .0048), hospitalizations (P = .0061), aeroallergen sensitization (P = .047), and positive asthma predictive indices (P = .007).

CONCLUSION

Among preschool children enrolled in the Acute Intervention Management Strategies trial, a subgroup was identified with severe intermittent wheezing characterized by atopic features and substantial illness-related symptom burden despite prolonged periods of wellness.

CLINICAL IMPLICATIONS: Preschool children with recurrent severe wheezing episodes experience significant illness-related morbidity and exhibit features of atopic predisposition.