Statistical analysis plan for the FiO2-C trial: effects of closed-loop automatic control of the inspiratory fraction of oxygen (FiO2-C) on outcomes of extremely preterm infants—a randomized-controlled parallel group multicentre trial for safety and efficacy

BackgroundExtremely low gestational age neonates (ELGANs, i.e. those born before 28 weeks postmenstrual age (PMA)) often require supplemental oxygen and frequently experience intermittent hypo- and hyperoxemic episodes. Exposure to episodes with inadequate oxygen concentrations has been shown to be associated with an increased risk of retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), neurodevelopmental impairment (NDI) and death. Closed-loop automatic control of the inspiratory fraction of oxygen (FiO2-C) reduces number and duration of hypo- and hyperoxemic episodes in ELGANs. Its impacts on clinically important short- and long-term outcomes such as ROP, BPD, NEC, NDI and mortality have not yet been studied.MethodsAn outcome-assessor-blinded, multicentre, randomized-controlled, parallel-group trial for superiority was designed to study the effects of FiO2-C (provided by standard infant ventilators) in addition to routine manual control (RMC) during respiratory support, compared to RMC only, on short- and long-term clinical outcomes in ELGANs. Two co-primary composite outcomes were defined: (i) death, severe ROP, BPD or NEC, assessed at 36 weeks PMA or, in case of ROP, until complete vascularization of the retina; (ii) death or NDI (defined as language/cognitive delay, motor impairment, severe visual impairment or hearing impairment), assessed at 2 years corrected age.ResultsPrimary outcomes will be compared between the two intervention groups using a Cochran-Mantel-Haenszel test. The factors considered for randomization (centre, sex and gestational age at birth (