The Development of Novel Clinical Tests to Diagnose and Monitor Asthma in Preschool Children

The Development of Novel Clinical Tests to Diagnose and Monitor Asthma in Preschool Children

The study will ascertain the ability of preschool lung function tests to distinguish healthy children from those with wheeze, and to differentiate phenotypes of wheezy children (high and low risk for asthma as defined by API) in order to predict response to therapy, and to explore the correlation between preschool lung function test results and symptoms, in order to develop objective methods for monitoring asthma.

In Canada, the most common chronic disease of childhood is asthma. Childhood asthma places a significant burden on the health care system (refn). No objective preschool asthma diagnostic tools exist, and the current gold-standard, the Asthma Predictive Index, does not provide information about lung function and symptom management. In this study, it is hypothesized that the lung clearance index (LCI), a value derived from the multiple breath washout test, will be the most sensitive, responsive discriminative test for preschool asthma. If it proves useful in the monitoring and diagnosis of preschool asthma, LCI has the potential to improve the clinical management and thus potentially significantly reduce hospitalization rates for preschool children suffering with asthma. In this unique data set, the investigators will also compare the relative utility of the forced oscillation technique (FOT) and preschool spirometry with the LCI in order to detect abnormalities amongst those children at high risk for preschool asthma. In addition, the impact of sleep apnea as a risk factor for and modifier of asthma will be investigated in this study. Furthermore, changes to the composition of the nasal microbiome during and after a wheezing episodes and the role of viral infections in wheezing exacerbations will be explored. Finally, the utility of new methods of diagnosing food allergy, such as the basophil activation test, will be examined in this Canadian cohort.

Inclusion Criteria (Wheezing Subjects):

• 3 to 5 years of age (36 to 71 months)
• Diagnosis of Asthma made by a physician in the emergency department
• History of at least two other wheezing episode within the previous 12 months
• Received salbutamol within 4hrs before emergency department visit, during current emergency department visit, or was prescribed salbutamol at discharge from emergency department.

Inclusion Criteria (Healthy Controls):

• 3 to 5 years of age (36 to 71 months)
• Free of a respiratory infection for a minimum of 4 weeks prior to the testing visit

Exclusion Criteria (both subjects and controls):

• History or coexistence of renal, chronic pulmonary, cardiac, neurological or systemic disease
• Born pre-term (< 35 weeks GA)
• Insufficient command of the English language