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Interfering factors to sensitivity and specificity of bronchial reactivity in children
R Kraemer1, C W Sommer, S Gschwend-Eigenmann
1Department of Paediatrics, University of Berne, Switzerland.
Insights
This study reveals distinct bronchial reactivity classes in children using carbachol provocation. Factors like air pollution and lung function significantly influence specificity in assessing bronchial hyperresponsiveness.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Clinical Allergy
Background:
- Bronchial hyperresponsiveness is a hallmark of asthma.
- Assessing bronchial reactivity in children requires careful consideration of influencing factors.
- The provocation dose of inhaled carbachol (PD65) is a key metric for bronchial reactivity.
Purpose of the Study:
- To characterize bronchial reactivity to carbachol in asthmatic and healthy children.
- To identify distinct classes of bronchial responsiveness based on PD65 values.
- To evaluate the impact of environmental and physiological factors on the specificity and sensitivity of PD65 measurements.
Main Methods:
- Measurement of bronchial reactivity using the PD65 (provocation dose for 65% increase in respiratory resistance) to inhaled carbachol.
- Analysis of PD65 frequency distribution in 355 asthmatic and 149 healthy children.
- Statistical analysis to identify peaks and classes of bronchial reactivity, and to assess the influence of air pollution and MEF50 on specificity.
Main Results:
- Frequency distribution of PD65 showed significant peaks at 240 and 1200 micrograms, defining hyperreactive, intermediate, and normo-reactive classes.
- The intermediate class exhibited overlap between healthy and asthmatic children.
- Considering air pollution and MEF50 improved specificity and sensitivity from 64% to 88%.
Conclusions:
- Bronchial reactivity to carbachol in children can be categorized into distinct classes.
- Air pollution and initial lung function (MEF50) are critical interfering factors affecting the interpretation of bronchial responsiveness tests.
- Accurate evaluation of bronchial responsiveness in pediatric populations necessitates accounting for these modulating variables.
Abstract:
Bronchial reactivity to carbachol, estimated by the PD65, the provocation dose of inhaled carbachol inducing a 65% increase of baseline respiratory resistance, was measured in 355 asthmatic children (age 8.7 +/- 2.6 years) and 149 healthy children (age 11.8 +/- 2.3 years). The frequency distribution of PD65 showed apart from 2 minima at 480 micrograms and 960 micrograms 2 significant peaks at 240 micrograms (p = 0.003) and 1200 micrograms (p = 0.01) to carbachol, reflecting a hyperreactive class (PD65 < 480 micrograms), an intermediate class (481 micrograms < PD65 < 960 micrograms) and a normo-reactive class (PD65 > 961 micrograms). The intermediate class is characterised by a considerable overlap between "health" and "disease". However, taking into account the degree of air pollution in which healthy children are living (best related factor to specificity) and the type of initial lung function disorder in asthmatic children, (the MEF50 to be the best related factor for specificity), weighed specificity and sensitivity improved from 64 to 88%. Evaluating bronchial responsiveness in children, such interfering factors should be strongly considered.