the study has recently ended, all information gathred as planed

Rational: The possible contribution of methacholine challenge test via spirometry to the clinical diagnosis of young children with various respiratory symptoms, the most appropriate spirometry index, and the proper cutoff point concentration that will define airway sensitivity have not yet been explored. Objectives: To assess airway reactivity by spirometry in a large group of children aged 3-6years with various respiratory symptoms.

We aimed to gather information concerning methacholine challenge test performed in children previously diagnosed with asthma (asthmatics) and 48 had prolonged cough (coughers) from the pediatric clinic at Meyer Children's Hospital.

Tests were performed by inhalation of triple-concentration increments (0.06 to13.9mg/ml/methacholine).

Spirometry was determined at baseline and after each inhalation in duplicate sets. End of test was defined by a fall of 20%FEV1 baseline (PC20-FEV1). PC20-FEV1<4.0mg/ml was considered positive). Results from the challenge were related to data from questionnaires concerning respiratory symptoms were analyzed at the end of the studies.

Inclusion Criteria:

• age 3- to 6-years
• respiratory diseases who were highly indicative of asthma diagnosis according to GINA guidelines [9]
• cough duration of more than 4 weeks
• normal chest auscultation and baseline FEV1>75% predicted for healthy preschool children, on the day of testing.

Exclusion Criteria:

• presence of other chronic respiratory conditions
• emergency room visit or the presence of respiratory infection within the last month
• oral or inhaled steroids or other anti-inflammatory medication taken in the last two weeks
• bronchodilator taken within 24-hours prior to the test.