From a search of case records a total of 10,752 children were identified as being in the required age group (1-15).
Further selection criteria included the presence of 'major key items'; treatment for asthma (past or present), wheezy bronchitis, diagnosis of asthma, and two or more episodes of wheeze or bronchospasm, and 'minor key items'; eczema, persistent cough, bronchitis, chestiness, family history of asthma (first degree relative), hay fever, bronchitis, allergy, seasonal symptoms, and five or more respiratory consultations, three or more prescriptions for respiratory problems, and two or more prescriptions for cough, linctus within the past year.
A final total of 3,373 children with at least one major key item or at least two minor key items were entered into the study. Children were initially stratified into age bands of 1-4, 5-9 and 10-15 inclusive. By a system of random generation the children were entered into the intervention group (n = 1585) and the control group (n = 1563). A total of 351 patients in the intervention group defaulted assessment in year 2 and 291 patients were not formally assessed (reason not stated). Power calculations in determining the sample size were not stated.