Outcome measures in childhood asthma.

Although evidence suggests that asthma onset occurs early in childhood, many standard asthma outcome measures are either impractical or unreliable in preschool-aged children. In this population, for instance, patient history and symptom reports rely on the observations of caregivers, who tend to underreport their child's asthma symptoms. Furthermore, the use of conventional measures of pulmonary function such as spirometry may be impractical in very young children. Recent clinical studies have used a variety of techniques to measure symptoms, pulmonary function, and cellular mediators of inflammation. Outcomes such as discontinuation and exacerbation rates, frequency of daytime and nocturnal symptoms, and caregiver assessments of quality of life can be useful measures in evaluating outcomes in young children with asthma. Some measures, such as plethysmography and inflammatory marker analysis, may be suitable options for assessing pulmonary function and predicting asthma susceptibility in preschool-aged children. Indeed, altered levels of inflammatory markers, including immunoglobulin E, interleukin-10, and exhaled nitric oxide, may be useful tools in diagnosing asthma, evaluating interventions, and assessing future risks for asthma symptomatology in very young children. Whether 1 or more of these outcome measures will prove useful clinically in improving the diagnosis and management of childhood asthma remains uncertain, although early research results are encouraging.