title: Trends in morbidity and mortality among very-low-birth-weight infants from 2003 to 2008 in Japan.
abstract: BACKGROUND
  Although medical care for very-low-birth-weight (VLBW) infants has improved over time, it is unclear how this has affected mortality and morbidity. To characterize these trends, a network database was analyzed.
  
  
  METHODS
  This is a cohort study of VLBW infants born from 2003 through 2008.
  
  
  RESULTS
  Over the 6-y period, 19,344 infants were registered and analyzed. Crude mortality rates among the infants at discharge decreased significantly (from 10.8 to 8.7%) during the study period. The greatest improvement in mortality was observed among infants with birth weights between 501 and 750 g (25.6-17.7 %). The odds ratio (OR) of mortality over year adjusted for potential confounders by a logistic regression model was 0.94 (95% confidence interval 0.92-0.97). Significant increases were observed in some morbidities, including symptomatic patent ductus arteriosus with an OR of 1.11 (1.09-1.13); late-onset adrenal insufficiency, 1.21 (1.17-1.26); and necrotizing enterocolitis/intestinal perforation, 1.10 (1.01-1.12). However, the severe form of intraventricular hemorrhage, with an OR of 0.98 (0.92-0.99), decreased significantly. Risk-adjusted trends in other morbidities showed no significant change.
  
  
  CONCLUSIONS
  Mortality of VLBW infants decreased significantly over the 6-y study period. Decreasing morbidity is essential for further improvement in the outcomes in VLBW infants.
authors.affiliation: Department of Neonatology, Maternal and Perinatal Center, Tokyo Women's Medical University, Tokyo, Japan. skusuda@boshi.twmu.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kusuda
authors.forename: Masanori
authors.initials: M
authors.lastname: Fujimura
authors.forename: Atsushi
authors.initials: A
authors.lastname: Uchiyama
authors.forename: Satsuki
authors.initials: S
authors.lastname: Totsu
authors.forename: Katsura
authors.initials: K
authors.lastname: Matsunami
mesh_terms: D001724:Birth Weight; D002423:Cause of Death; D016009:Chi-Square Distribution; D005865:Gestational Age; D017052:Hospital Mortality / Q000639:trends*; D006761:Hospitals / Q000639:trends; D006801:Humans; D007226:Infant Mortality / Q000639:trends*; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000401:mortality* / Q000628:therapy; D007234:Infant, Premature; D019102:Infant, Very Low Birth Weight; D007363:Intensive Care Units, Neonatal / Q000639:trends; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D015999:Multivariate Analysis; D016017:Odds Ratio; D011379:Prognosis; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors