Bronchopulmonary dysplasia in very low birth weight subjects and lung function in late adolescence

OBJECTIVES. The purpose of this work was to determine the relationship between lung function in late adolescence and bronchopulmonary dysplasia, to establish whether lung function changed more from earlier in childhood in those with bronchopulmonary dysplasia, and to assess the effect of different definitions of bronchopulmonary dysplasia on respiratory outcome. METHODS. Subjects were composed of 147 survivors of birth weight < 1500 g from the Royal Women's Hospital ( Melbourne, Australia) born during 1977 - 1982 and who had lung function tests at a mean age of 18.9 years. Of the 147 subjects, 33 ( 22%) had bronchopulmonary dysplasia in the newborn period. Lung function was measured according to American Thoracic Society guidelines. RESULTS. All of the lung function variables reflecting airflow were substantially diminished in the bronchopulmonary dysplasia group, but lung volumes were not significantly different. More subjects in the bronchopulmonary dysplasia group had reductions in airflow in the clinically significant range ( eg, forced expired volume in 1 second/forced vital capacity ratio < 75%; bronchopulmonary dysplasia: 42.4% [ 14 of 33]; and no bronchopulmonary dysplasia: 16.4% [ 18/114]). Results were not substantially affected after adjustment for confounding variables, including intrauterine growth restriction or birth weight. Compared with earlier in childhood, the forced expired volume in 1 second/forced vital capacity ratio deteriorated more in bronchopulmonary dysplasia subjects between 8 and 18 years. Lung function results varied little with different definitions of bronchopulmonary dysplasia. CONCLUSIONS. Subjects of very low birth weight with bronchopulmonary dysplasia in the newborn period have poorer lung function in late adolescence than those without bronchopulmonary dysplasia, and their lung function may be deteriorating at a more rapid rate.