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Longitudinal Evaluation of Airway Function 21 Years after Preterm Birth

¹ Department of Paediatric Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom; and ² Children's Asthma Centre and Institute for Lung Health, University of Leicester, Leicester Royal Infirmary, Leicester, United Kingdom

Correspondence and requests for reprints should be addressed to A. Bush, M.D., F.R.C.P., F.R.C.P.C.H., Department of Paediatric Respiratory Medicine, Royal Brompton Hospital, Sydney Street, London SW3 6NP, UK. E-mail: a.bush{at}rbh.nthames.nhs.uk

Rationale: There are limited longitudinal data about respiratory morbidity and lung function after preterm birth into adulthood.

Objectives: To determine the evolution of respiratory symptoms, spirometry, and airway hyperresponsiveness of ex-preterm subjects from childhood into adulthood.

Methods: Ex-preterm subjects (median birth weight, 1,440 g; median gestation, 31.5 wk), recruited at birth (not treated with surfactant), had excess respiratory symptoms, airway obstruction, and increased airway hyperresponsiveness in mid-childhood. At a median age of 21.7 years, 60 of these subjects (the index study group) and 50 healthy term control subjects were recruited to determine respiratory morbidity and spirometry.

Measurements and Main Results: Respiratory symptom questionnaire, spirometry, and methacholine challenge test. The index study group had significantly more respiratory symptoms (16 of 60) than did control subjects (4 of 50) (odds ratio, 4.2; 95% confidence interval, 1.3 to 13.5; P = 0.01), but no significant difference in measured spirometry. Specifically, in the index study group and control subjects, the mean z scores (95% confidence interval of the group difference) for the FEV₁ were –0.60 and –0.58 (–0.44 to 0.49), respectively (P = 0.92); for the forced mid-expiratory flow they were –1.02 and –0.86 (–0.33 to 0.64), respectively (P = 0.52); and for the FVC they were –0.29 and –0.33 (–0.46 to 0.38), respectively (P = 0.85). Ex-preterm adults did not show evidence of increased airway hyperresponsiveness compared with control subjects, 23 and 19%, respectively (P = 0.89).

Conclusions: There are still excess respiratory symptoms 21 years after preterm birth. Reassuringly, this longitudinal study did not show evidence of persistent airway obstruction or airway hyperresponsiveness in ex-preterm adults.

Key Words: spirometry • respiratory symptoms • airway hyperresponsiveness

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject The impact of preterm birth on longitudinal respiratory function in adulthood is not well understood and available data are currently limited. What This Study Adds to the Field Ex-preterm subjects have more respiratory symptoms in adulthood than their peers. Although impaired lung function tracks from childhood to adulthood, there is some recovery of lung function during this time period.