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Objective: To investigate the characteristics of persistent pulmonary hypertension of the newborn (PPHN) in extremely preterm infants and its impact on neurodevelopmental outcomes at 3 years of age.Design: A retrospective multicentre cohort study.Settings: 202 tertiary perinatal centres registered in the Neonatal Research Network of Japan (NRNJ).Patients: Infants born at <28 weeks of gestational age (GA), between 2003 and 2012, were extracted from tertiary perinatal centres participating in NRNJ.Main Outcome Measures: Demographic characteristics, morbidity, interventions and mortality were compared for infants with and without PPHN. Multivariable logistic analysis was performed to evaluate the impact of PPHN on long-term neurodevelopmental outcomes (the prevalence rate of cerebral palsy, need for home oxygen therapy, and visual, hearing and cognitive impairment) at 3 years of age.Results: The prevalence of PPHN among the 12 954 extremely preterm infants enrolled was 8.1% (95% CI 7.7% to 8.6%), with the trend increasing annually, and a higher proportion as GA decreased: 18.5% (range, 15.2% to 22.4%) for infants born at 22 weeks compared with 4.4% (range, 3.8% to 5.2%) for those born at 27 weeks. Clinical chorioamnionitis and premature rupture of membranes were associated with PPHN. On multivariate analysis of the data from 5923 infants followed up for 3 years, PPHN was a significant independent risk factor for visual impairment (adjusted OR, 1.42, 95% CI 1.03 to 1.97).Conclusions: The prevalence of PPHN in extremely preterm infants has been increasing over the past decade in Japan. Clinicians should be aware of visual impairments as a neurodevelopmental abnormality among infants with PPHN. [ABSTRACT FROM AUTHOR]

Objectives: To determine the feasibility of clinical trials of newly developed treatments or standardisation of existing practices to further improve outcomes among very low birth weight (VLBW) infants, a nationwide database was analysed with a two-dimensional approach using two multivariate logistic models. Design: Retrospective observational analysis. Setting: Level III perinatal centres in Japan. Participants: 15 920 VLBW infants admitted at 38 participating centres from 2003 through 2010. Outcome measures: Clinical information for the infants was collected until discharge from the centres. A multivariate logistic model identified practices and morbidities associated with mortality. Then, those which were significantly associated with mortality were analysed using a multilevel logistic model. The residues calculated by the multilevel analysis were used as an indicator of centre variation. Results: Among practices, antenatal steroids and intubation at birth showed relatively high centre variations (0.9 and 0.8) and favourable ORs (0.7 and 0.5) for mortality, while caesarean section showed a low centre variation (0.4) and a favourable OR (0.8). Sepsis and air leak showed high centre variations (0.4 and 0.4) and high ORs (3.8 and 3.4) among morbidities. Pulmonary haemorrhage, persistent pulmonary hypertension of the newborn, and intraventricular haemorrhage showed moderate variations (0.2, 0.3 and 0.2, respectively) and high ORs (5.6, 4.1 and 2.9, respectively). In contrast, necrotising enterocolitis showed the lowest variation (0.1) and a high OR (4.9). Conclusions: The two-dimensional approach has clearly demonstrated the importance of clinical trial or standardisation. The practices and morbidities with low centre variations and high ORs for mortality must be improved through clinical trials of newly introduced techniques, while standardisation must be considered for practices and morbidities with a high centre variation. Trial registration: The database was registered as UMIN000006961. [ABSTRACT FROM AUTHOR]