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Table 1 Definitions for patient characteristics at enrolment, data on trial interventions and co-interventions, and neonatal outcomes.

From: Elective high-frequency oscillatory ventilation in preterm infants with respiratory distress syndrome: an individual patient data meta-analysis

Variable Definition
Patient-level information on characteristics at enrolment
   Complete course of antenatal corticosteroids A course of at least 2 doses started > 48 hours before delivery or completed > 24 hours before delivery
   Antenatal corticosteroids, any treatment Any antenatal treatment with corticosteroids, regardless of the interval with delivery
   Chorioamnionitis As defined in the trial
   Oxygenation index (OI) OI = MAP × FiO2 × 100/P aO2 With
     MAP = mean airway pressure
     FiO2 = fractional inspired oxygen
     P aO2 = partial arterial oxygen tension
Patient-level information on trial intervention and co-interventions
   MAP at stabilization Mean airway pressure in the first 24 hours after randomization.
   FiO2 at stabilization Fractional inspired oxygen in the first 24 hours after randomization.
   Postnatal corticosteroids Postnatal treatment with corticosteroids for the prevention or treatment of bronchopulmonary dysplasia
   Early administration of cyclo-oxygenase inhibitor Administration of indomethacin or ibuprofen in the first 24 hours of life in order to prevent patent ductus arteriosus or intracranial haemorrhage
Neonatal outcomes
   Death Death before discharge from neonatal intensive care unit (NICU)
   BPD at 36 weeks PMA Oxygen therapy at the postmenstrual age of 36 weeks
   Severe adverse neurological event Intracranial haemorrhage grade 3 or 4, and/or cystic periventricular leukomalacia
   Gross pulmonary air leak Pneumothorax and/or pneumomediastinum and/or pneumopericardium
   PDA requiring treatment Patent ductus arteriosus requiring treatment with non-steroidal anti-inflammatory drugs or surgery
   Any pulmonary air leak Gross pulmonary air leak and/or pulmonary interstitial emphysema (PIE)
   Neurological disability Motor and/or cognitive and/or auditory and/or visual impairment