Diagnostic Approach for Asthma in Preschool Children

Age-Specific Limitations of Testing

In preschool children under 5 years, spirometry and pulmonary function testing have significant limitations, and detailed history and physical examination have the highest diagnostic value, as recommended by the American Thoracic Society 1
Spirometry is not feasible in children under 5 years, as most preschool children cannot successfully perform the required maneuvers for acceptable spirometry results, according to the American College of Chest Physicians 1
Pulmonary function testing in preschool children has very poor diagnostic accuracy due to substantial overlap between measurements in healthy children and those with asthma, as stated by the American Academy of Pediatrics 1

The European Respiratory Society guidelines recommend that the diagnosis of asthma in preschool children should rely primarily on clinical assessment, including history and physical examination, with a focus on recurrent wheeze, frequency and pattern of symptoms, and response to bronchodilator treatment 2
Auscultation for wheeze is a crucial part of the physical examination, as it is the characteristic polyphonic whistling sound heard mainly during expiration, as described by the European Respiratory Society 3
The American Academy of Allergy, Asthma, and Immunology recommends that children with chronic cough as the only symptom are unlikely to have asthma, and alternative diagnoses should be considered 3

The American College of Allergy, Asthma, and Immunology advises against waiting for objective testing that cannot be performed at this age, as it delays treatment and contributes to morbidity, and recommends a thorough history and physical examination instead 1
The European Respiratory Society warns against relying on cough alone for diagnosis, as children with chronic cough as the only symptom are unlikely to have asthma, and recommends considering alternative diagnoses 3
The American Thoracic Society recommends that a therapeutic trial of medium-dose inhaled corticosteroids with as-needed SABA may be considered if diagnosis remains uncertain, with convincing parental report of response 6