[Discrepancies between diagnosed asthma, asthma-like symptoms and a test for abnormal lung function]

Area of Science:

• Pediatric respiratory medicine
• Clinical immunology
• Epidemiology

Context:

• Asthma diagnosis in adolescents lacks clarity regarding test interrelationships.
• Understanding how symptoms and objective tests align is crucial for accurate diagnosis.
• Population-based studies are needed to validate diagnostic approaches in children.

Purpose:

• To assess the interrelationship between physician-diagnosed asthma, asthma-like symptoms, and abnormal airway function in schoolchildren.
• To determine the optimal combination of diagnostic tests for identifying asthma in adolescents.
• To evaluate the utility of spirometry, exercise challenge, methacholine provocation, and peak flow monitoring.

Summary:

• A study of 495 schoolchildren (12-15 years) evaluated asthma diagnosis using questionnaires, spirometry (FEV1%), treadmill exercise (EXE), methacholine provocation (PD15), and twice-daily peak expiratory flow (PEF) monitoring.
• Methacholine challenge testing (PD15) alone identified 75% of symptomatic subjects with positive tests, and in combination with PEF monitoring, identified 89%.
• While agreement between tests was weak, significant associations were found between PD15 and EXE, PEF and EXE, and FEV1% and PD15, suggesting distinct pathophysiological aspects.

Impact:

• Peak expiratory flow variability and methacholine responsiveness appear to reflect different airway pathophysiologies.
• Combined use of PEF monitoring and methacholine challenge testing shows promise as an epidemiological screening tool for asthma in adolescents.
• Findings contribute to refining diagnostic strategies for asthma in pediatric populations.