Adverse effects of smoking on respiratory function in young adults born weighing less than 1000 grams

Objective. To determine whether active smoking has an adverse impact on respiratory function of young adults of extremely low birth weight (ELBW; birth weight < 1000 g). Methods. This was a cohort study of 60 consecutive ELBW survivors who were born during 1977-1980 at Royal Women's Hospital, Melbourne, Australia. Respiratory function was measured on 44 (73%) of the subjects at a mean age of 20.2 years (standard deviation: 1.0 year). Respiratory function had also been measured on 42 of the 44 subjects at 8 years of age. Respiratory function was compared between the 14 smokers and the 30 nonsmokers. Results. Several respiratory function variables reflecting airflow (the forced expired volume in 1 second [FEV1]/forced vital capacity [FVC] ratio; flow rates at 75%, 50%, and 25% of vital capacity; and mid-expiratory flow from 25% to 75% of vital capacity) were significantly diminished in smokers. The proportion with a clinically important reduction in the FEV1/FVC ratio (< 75%) was significantly higher in smokers (64%) than in nonsmokers (20%). There was a significantly larger decrease in the FEV1/FVC ratio between ages 8 and 20 years in the smokers (mean change: -8.2%; 95% confidence interval: -14.1% to -2.4%) Conclusions. Active smoking by young adult survivors of ELBW is associated with reduced respiratory function.