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Determinants of reproducibility of lung function tests in children aged 7 to 10 years
M Studnicka1, T Frischer, M Neumann
1Pulmologisches Zentrum der Stadt Wien, I. Interne Abteilung, Universitätskinderklinik Wien, Austria.
Insights
Childhood lung function (LF) test reproducibility improves with training. Poor LF test results in children with respiratory symptoms like wheezing or asthma may indicate underlying issues, necessitating careful interpretation.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Clinical Diagnostics
Background:
- Lung function (LF) tests are crucial for diagnosing childhood lung diseases.
- Individual variability in LF test results can obscure true between-subject differences.
- Increased LF variability is associated with respiratory conditions in children.
Purpose of the Study:
- To determine the reliability of key lung function parameters in children.
- To assess the impact of training on LF test reproducibility.
- To identify factors associated with poor LF test reproducibility in pediatric subjects.
Main Methods:
- Recorded two LF tests (FEV1, FVC, MEF50) 5 minutes apart in 598 children.
- Calculated reliability coefficients (Crel) for LF parameters.
- Assessed reproducibility in trained versus untrained children and analyzed determinants of excessive FEV1 variability (>120 ml difference).
Main Results:
- High reliability coefficients were found for volume parameters (FEV1: 0.96, FVC: 0.94) compared to MEF50 (0.91).
- Reliability for FEV1 was lower in untrained children (0.91) but improved significantly with subsequent testing.
- Excessive FEV1 variability (10% of children) was linked to wheeze, shortness of breath, asthma diagnosis, and bronchial hyperresponsiveness.
Conclusions:
- Increased LF variability is common in young children unfamiliar with testing and those with respiratory symptoms.
- Training in LF testing procedures enhances reproducibility in pediatric populations.
- Caution is advised when interpreting LF test results in symptomatic children due to potential variability.
Abstract:
Lung function (LF) tests are part of many investigations in childhood lung disease. However, individual reproducibility of LF will confound between-subject differences. At the same time, increased LF variability has been linked to respiratory disease. In a sample of 598 children, two LF tests, separated by a 5-min interval, were recorded, and reliability (Rel) of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and maximal expiratory flow at 50% of FVC (MEF50) was determined. Rel was also assessed in children trained and untrained in the performance of LF. To investigate determinants of reproducibility for FEV1, the absolute difference between two repeated tests was calculated. Whenever this difference was > 120 ml, a child was considered to demonstrate excessive variability (poor reproducibility) in FEV1. For volume parameters coefficients of reliability (Crel) were found to be better than for MEF50 (FEV1: 0.96; FVC: 0.94, MEF50: 0.91). In untrained children Crel for FEV1 was only 0.91, but it was increased in subsequent visits (0.98, 0.97, and 0.97 at the second, third, and fourth tests, respectively). Excessive variability in FEV1 was observed in 10% of children and was related to the presence of wheeze [odds ratio (OR) 6.31; 95% confidence interval (CI) 1.78-22.4), shortness of breath (OR 3.14; 95% CI 1.00-9.93), a diagnosis of asthma (OR 6.25; 95% CI 1.76-22.1), and bronchial hyperresponsiveness (OR 4.30; 95% CI 2.07-8.94). We conclude that increased variability of LF is likely to be present in young children not accustomed to the testing procedure and in children with respiratory symptoms. Therefore, before guidelines for LF testing are applied, children should be trained to perform the tests and we should be cautious in the interpretation of test results in children who present with symptoms.