Thirteen-year mortality and morbidity in preterm infants in Switzerland

Abstract

Objective: To report the population-based, gestational age (GA)-stratified mortality and morbidity for very preterm infants over 13 years in Switzerland.

Design: A prospective, observational study including 95% of Swiss preterm infants (GA <32 weeks) during three time periods: 2000-2004 (P1), 2005-2008 (P2) and 2009-2012 (P3).

Setting: The Swiss Neonatal Network, covering all level III neonatal intensive care units (NICUs) and affiliated paediatric hospitals.

Patients: 8899 live-born preterm infants with GA <32 weeks.

Main outcome measures: Trends in GA-specific mortality (overall, delivery room and NICU), 'survival free of major complications' and major short-term morbidities: bronchopulmonary dysplasia (BPD, oxygen requirement at 36 weeks), grades 3 and 4 intraventricular haemorrhage (IVH 3-4), necrotising enterocolitis (NEC) and cystic periventricular leukomalacia (cPVL).

Results: Survival rate was 84.4%; 5.7% died in the delivery room and 9.9% died in the NICU. Neonatal mortality was 8.6% and post-neonatal mortality in NICU admissions was 1.3%. Reductions were observed in overall mortality from 18.4% (95% CI 17.0% to 19.8%) in P1 to 13.8% (13% to 15%) in P3, NICU mortality from 12.6% (11.4% to 13.8%) to 8.2% (7.2% to 9.2%) and IVH 3-4 from 7.8% (6.8% to 8.7%) to 5.8% (4.9% to 6.6%). There was no change in the incidence of cPVL and NEC. The BPD (oxygen requirement at 36 weeks) incidence displayed a U-shaped distribution across the three time periods. Overall, 71.0% (70.0% to 72.0%) had 'survival free of major complications' at the time of hospital discharge, and this significantly improved from 66.7% (65.0% to 68.4%) to 72.4% (70.8% to 74.0%) between P1 and P3.

Conclusions: Survival rates of very preterm infants increased with decreasing delivery room and neonatal mortalities, mostly in extremely preterm infants. The incidence of IVH 3-4 decreased, whereas the incidences of cPVL, NEC and BPD (oxygen requirement at 36 weeks) remained largely unchanged from 2000 to 2012 in Switzerland.

Keywords: Epidemiology; Mortality; Neonatology; Pathology; Qualitative research.