Study population and data source
This study included adolescents who were born between 2003 and 2005. They were classified into the following 3 groups: Extremely preterm adolescents (up to 28 weeks’ GA) with associated BPD (EP-BPD); extremely preterm adolescents without BPD (EP-noBPD); moderate-late preterm adolescents (MLP; 32 to < 37 weeks’ GA). The accepted definitions of BPD used by each center at the time of diagnosis were as follows: 1 Supplementary oxygen requirements for ≥ 28 days, regardless of the situation at 36 weeks post-menstrual age; 2National Heart, Lung and Blood Institution Workshop definitions (Jobe and Bancalari)8: 2a, Mild BPD; 2b, Moderate BPD; 2c, Severe BPD; 3 Requirement for supplemental oxygen at 36 weeks post-menstrual age. We regrouped EP-BPD patients into the following 2 subgroups according to disease severity: “low severity BPD” (definitions 1 and 2a) and “high severity BPD” (definitions 2b, 2c, and 3). The following were considered exclusion criteria: (1) mental retardation; (2) disabling cerebral palsy; (3) severe gastroesophageal reflux; and (4) history of lung resection, airway surgery, or cardiac surgery.
In each hospital, data provided by the medical records department were used to create a list of patients for each group. Telephone calls were conducted in chronological order, beginning with participants born in January 2003, and appointments were made for those who were interested. For every EP-BPD adolescent who agreed to participate, 1 EP-noBPD adolescent and 1 MLP adolescent were also selected. They were matched in sex and date of birth as closely as possible.