Identifying problematic severe asthma in the individual child--does lung function matter?

Area of Science:

• Pediatric Pulmonology
• Respiratory Medicine
• Asthma Research

Background:

• Lung function tests, typically using a forced expiratory volume in 1 second (FEV1) <80% predicted, are standard for classifying asthma severity.
• This classification method may be less accurate in children, as lung function impairment is often less pronounced in pediatric asthma patients.

Purpose of the Study:

• To evaluate the effectiveness of lung function measurements in distinguishing severe childhood asthma from mild-to-moderate asthma.
• To determine if current spirometry thresholds are relevant for diagnosing severe asthma in children.

Main Methods:

• A clinical assessment was performed on 51 school-aged children with problematic severe asthma, 37 with mild-to-moderate asthma, and 29 healthy controls.
• Problematic severe asthma was defined by poor control despite high-dose inhaled corticosteroids and other controller medications.

Main Results:

• While baseline FEV1 was lower in severe asthmatics, FEV1 <80% predicted had low sensitivity (41%) for differentiating severe from mild-to-moderate asthma.
• Receiver-operating characteristic analysis suggested an optimal FEV1 cut-off of 90% predicted (61% sensitivity, 83% specificity).
• Other measures like FEV1/FVC, FEF(25-75), exhaled nitric oxide, and bronchial hyperresponsiveness did not effectively discriminate between the groups.

Conclusions:

• Spirometric measurements, particularly the standard FEV1 <80% predicted threshold, are not sensitive enough to accurately diagnose problematic severe asthma in children.
• A higher FEV1 threshold may be necessary for improved discrimination in pediatric populations.