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Infants with flow limitation at 4 weeks: outcome at 6 and 11 years
Stephen W Turner1, Lyle J Palmer, Peter J Rye
1University Department of Paediatrics, Princess Margaret Hospital for Children, Perth, Western Australia, Australia.
Insights
Infants with expiratory flow limitation show persistent reduced lung function and increased airway responsiveness into childhood. This early sign may identify a distinct at-risk group for later respiratory issues.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Longitudinal Cohort Studies
Background:
- Infants with expiratory flow limitation exhibit reduced lung function and increased airway responsiveness (AR).
- These infants are diagnosed with asthma more frequently by age 2.
- The persistence of these findings throughout childhood was investigated.
Purpose of the Study:
- To determine if reduced lung function and increased AR in flow-limited infants persist into childhood.
- To assess the long-term respiratory health outcomes in children identified with early expiratory flow limitation.
Main Methods:
- Longitudinal study of 243 infants, analyzing data from ages 3 to 11 years.
- Assessed lung function, airway responsiveness, and wheeze in a cohort with and without expiratory flow limitation.
- Statistical analysis included odds ratios, confidence intervals, and p-values.
Main Results:
- Flow-limited children had increased wheeze at age 4 (OR, 4.25).
- At age 6, the flow-limited group showed greater AR and reduced mean FEV1 and FEF25-75.
- At age 11, greater AR persisted, with a trend toward reduced FEF25-75.
Conclusions:
- Early expiratory flow limitation in infancy is associated with persistent reduced lung function and increased airway responsiveness in childhood.
- This physiologic abnormality may identify a distinct at-risk group for later respiratory problems, separate from typical asthma.
- Findings suggest early flow limitation as a potential biomarker for long-term respiratory health.
Abstract:
Within a longitudinal study of lung function in 243 infants, we identified a group of 23 individuals with flow limitation in tidal expiration. In infancy, flow-limited children have reduced lung function and increased airway responsiveness (AR), and at 2 years of age they are diagnosed with asthma more frequently. We hypothesized that these observations would persist throughout childhood. Data from ages 3 to 11 years were analyzed. Only at 4 years of age did the flow-limited group have increased wheeze compared with other cohort members (odds ratio, 4.25; 95% confidence interval [CI], 1.11 to 16.2; p = 0.04; n = 114). At 6 years of age, 117 cohort members were seen. The flow-limited group (n = 14) had greater AR (p = 0.009) and reduced mean FEV(1) (131 ml; 95% CI, 16 to 246; p = 0.03) and FEF(25-75) (0.28 L/second; 95% CI, 0.05 to 0.52; p = 0.02). At 11 years of age, 183 children were seen and the flow-limited group (n = 18) had greater AR (p = 0.02) and a trend toward reduced mean FEF(25-75) (0.24 L/second; 95% CI, -0.02 to 0.49; p = 0.08). Atopy and parental asthma were not increased in the flow-limited group. We suggest that the physiologic abnormality that causes flow limitation in early infancy may identify an at-risk group, different from asthma, who have reduced lung function and increased airway responsiveness in later life.