title: Intellectual outcomes of extremely preterm infants at school age.
abstract: BACKGROUND
  The survival rate of extremely preterm (EP) infants (<28 weeks of gestation) has improved dramatically, and there is great interest in the long-term prognosis. The aim of this study was to elucidate the influence of prenatal and postnatal care on long-term intellectual outcome in EP infants.
  
  
  METHODS
  Subjects were EP infants admitted to the neonatal intensive care unit from 1982 to 2005. The survival rate and neurodevelopmental outcomes at 6 years of age were analyzed for the periods 1982-1991 (period 1) and 1992-2005 (period 2). Logistic regression analysis was performed to examine risk factors for intellectual impairment.
  
  
  RESULTS
  Survival rate improved significantly from 84.5% (period 1) to 92.4% (period 2; P = 0.007). Follow-up data were obtained from 92 children in period 1 (69.7% of survivors) and from 245 in period 2 (72.3% of survivors). The incidence of intellectual impairment increased from 16.3% (period 1) to 31.0% (period 2). Significant factors associated with intellectual impairment were period 2 (OR, 3.53; P = 0.007), supplemental oxygen at 36 weeks' corrected age (OR, 2.22; P = 0.012), number of days in the hospital (OR, 1.01; P = 0.012), intraventricular hemorrhage (IVH; OR, 3.05; P = 0.024), and later tube-feeding commencement date (OR, 1.10; P = 0.032).
  
  
  CONCLUSIONS
  Despite an increase in survival rate, the rate of intellectual impairment increased in period 2. According to risk factor analysis, reducing the incidence of chronic lung disease and/or apnea, IVH, and nutritional deprivation is a key factor in improving the intellectual outcomes of EP infants.
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Maya
authors.initials: M
authors.lastname: Asami
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kamei
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Misato
authors.initials: M
authors.lastname: Nakakarumai
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Shirasawa
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Manami
authors.initials: M
authors.lastname: Akasaka
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Nami
authors.initials: N
authors.lastname: Araya
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Tanifuji
authors.affiliation: Department of Pediatrics, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Chida
mesh_terms: D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D008607:Intellectual Disability / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D015931:Intensive Care, Neonatal; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D018743:Perinatal Care; D012307:Risk Factors; D015996:Survival Rate
keywords: extremely preterm infant; follow-up study; outcome study; risk factor