title: Trends and centre-to-centre variability in survival rates of very preterm infants (<32 weeks) over a 10-year-period in Switzerland.
abstract: BACKGROUND
  The publication of Swiss guidelines for the care of infants at the limit of viability (22-25 completed weeks) was followed by increased survival rates in the more mature infants (25 completed weeks). At the same time, considerable centre-to-centre (CTC) differences were noted.
  
  
  OBJECTIVE
  To examine the trend of survival rates of borderline viable infants over a 10-year-period and to further explore CTC differences.
  
  
  METHODS
  Population-based, retrospective cohort study.
  
  
  METHODS
  All nine level III neonatal intensive care units (NICUs) and affiliated paediatric hospitals in Switzerland.
  
  
  METHODS
  6532 preterm infants with a gestational age (GA) <32 weeks born alive between 1 January 2000 and 31 December 2009.
  
  
  METHODS
  Trends of GA-specific delivery room and NICU mortality rates and survival rates to hospital discharge were assessed. For CTC comparisons, centre-specific risk-adjusted ORs for survival were calculated in three GA groups: A: 23 0/7 to 25 6/7 weeks (n=976), B: 26 0/7 to 28 6/7 weeks (n=1943) and C: 29 0/7 to 31 6/7 weeks (n=3399).
  
  
  RESULTS
  Survival rates of infants with a GA of 25 completed weeks which had improved from 42% in 2000/2001 to 60% in 2003/2004 remained unchanged at 63% over the next 5 years (2005-2009). Statistically significant CTC differences have persisted and are not restricted to borderline viable infants.
  
  
  CONCLUSIONS
  In Switzerland, survival rates of infants born at the limit of viability have remained unchanged over the second half of the current decade. Risk-adjusted CTC outcome variability cannot be explained by differences in baseline demographics or centre case loads.
authors.affiliation: Neonatal and Paediatric Intensive Care Unit, Kinderspital Luzern, Spitalstrasse, CH-6000 Luzern 16, Switzerland. thomas.berger@luks.ch
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Berger
authors.forename: Martina A
authors.initials: MA
authors.lastname: Steurer
authors.forename: Andreas
authors.initials: A
authors.lastname: Woerner
authors.forename: Philipp
authors.initials: P
authors.lastname: Meyer-Schiffer
authors.forename: Mark
authors.initials: M
authors.lastname: Adams
mesh_terms: D015331:Cohort Studies; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000401:mortality; D007363:Intensive Care Units, Neonatal; D017063:Outcome Assessment, Health Care; D017410:Practice Guidelines as Topic; D015996:Survival Rate / Q000639:trends*; D013557:Switzerland / Q000453:epidemiology