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Lung function in severe pediatric asthma: a longitudinal study in children and adolescents in Brazil
Mônica Versiani Nunes Pinheiro de Queiroz1,2, Cristina Gonçalves Alvim3, Álvaro A Cruz4
1Department of Pediatrics, School of Medicine, Federal University of Ouro Preto, Ouro Preto, Brazil.
Insights
High doses of inhaled corticosteroids (ICS) in children and adolescents with severe asthma did not improve lung function. Doses exceeding 800 µg/day showed no gains and indicated potential irreversible small airway impairment.
Area of Science:
- Pediatric Pulmonology
- Asthma Management
- Respiratory Medicine
Background:
- Severe asthma in children and adolescents often requires high doses of inhaled corticosteroids (ICS) for control.
- Evaluating the efficacy of high-dose ICS on lung function in this population is crucial.
Purpose of the Study:
- To assess lung function changes in Brazilian outpatients (children and adolescents) with severe asthma treated with high-dose ICS.
- To compare lung function outcomes based on ICS dosage: 800 µg/day versus >800 µg/day.
Main Methods:
- A 3-year longitudinal study analyzing 384 spirometry tests from 65 severe asthma patients (aged 6-18).
- Patients were divided into two groups based on ICS dose: 800 µg/day or >800 µg/day (budesonide or equivalent).
Main Results:
- Overall, significant improvements in forced expiratory volume in one second (FEV1)% and FEV1/forced vital capacity (FVC)% ratio were observed.
- Patients receiving >800 µg/day ICS showed no statistical improvement in FEV1, FEV1/FVC ratio, or FEF25-75% as predicted values.
- A significant reduction in the z-score for FEF25-75% and post-bronchodilator FEV1% was noted in the >800 µg/day group.
Conclusions:
- High-dose ICS (>800 µg/day) in severe asthma did not lead to further lung function improvement in children and adolescents.
- Evidence suggests a plateau phase and potential irreversible small airway impairment with doses exceeding 800 µg/day.
- Current ICS dosing strategies may not enhance lung function beyond a certain threshold in this patient group.
Background:
In severe asthma, high doses of inhaled corticosteroids (ICS) are used in order to achieve clinical and functional control. This study aimed to evaluate lung function in outpatients (children and adolescents) with severe asthma in Brazil, all of whom were treated with high doses of ICS. We evaluated all spirometry tests together and by ICS dose: 800 and > 800 µg/day.
Methods:
This was a 3-year longitudinal study in which we analyzed 384 spirometry tests in 65 severe asthma patients (6-18 years of age), divided into two groups by the dose of ICS (budesonide or equivalent): 800 and > 800 µg/day.
Results:
At baseline, the forced expiratory volume in one second (FEV1) and the FEV1/forced vital capacity (FVC) ratio were both < 80% of the predicted values in 50.8% of the patients. The median age of the patients was 10.4 years (interquartile range 7.8-13.6 years). In the sample as a whole, there were significant increases in FEV1% and in the FEV1/FVC% ratio (p = 0.01 and p < 0.001, respectively) over the course of the study. In the > 800 µg/day group, there were no statistical increases or decreases in FEV1, the FEV1/FVC ratio, or forced expiratory flow between 25 and 75% of the FVC (FEF25-75%), when calculated as percentages of the predicted values. However, the z-score for FEF25-75% showed a statistically significant reduction, in the sample as a whole and in the > 800 µg/day group. Also in the > 800 µg/day group, there was a significant reduction in the post-bronchodilator FEV1% (p = 0.004).
Conclusions:
The fact that the spirometric parameters (as percentages of the predicted values) remained constant in the > 800 µg/day group, whereas there was a gain in lung function in the sample as a whole, suggests an early plateau phase in the > 800 µg/day group. However, there was some loss of lung function in the > 800 µg/day group, as evidenced by a decrease in the z-score for FEF25-75%, suggesting irreversible small airway impairment, and by a reduction in the post-bronchodilator FEV1%, suggesting reduced reversibility of airway obstruction. Among children and adolescents with severe asthma, the use of ICS doses higher than those recommended for age does not appear to improve lung function.
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