Mortality Risk Amongst Very Low Birth Weight Infants in the Republic of Ireland
The National Perinatal Epidemiology Centre, in association with the NICORE Group, publishes Mortality Risk Amongst Very Low Birth Weight Infants Born in the Republic of Ireland Report 2014-2016. This is the first national report to include three years of data on very low birth weight (VLBW) infants born in the Republic of Ireland (ROI) in the years 2014 to 2016. This report is produced by the Neonatal Intensive Care Outcomes Research and Evaluation (NICORE) ROI group and facilitated by the National Perinatal Epidemiology Centre (NPEC). The Vermont Oxford Network (VON) Ireland database holds data on 1,812 very low birth weight (VLBW) infants born in Ireland in the years 2014-2016. The findings in this report are based on the 1,765 infants with a record from their hospital of birth: 580 infants born in 2014, 608 born in 2015 and 577 born in 2016.
The gestational ages of the VLBW infants ranged from 21 weeks to 33 weeks and their birth weights ranged from 360g to 2,640g. Over the three years, more Irish VLBW infants died prior to discharge home or their first birthday than their VON counterparts (16.9% versus 14.5%, p=0.005). Following adjustment for differences in the profile of the Irish and VON populations, the standardised mortality rate (SMR) indicated that the mortality risk for VLBW infants born in Ireland was 1.17 times higher than expected and represented a statistically significant excess mortality (95% CI: 1.05, 1.29). The excess mortality diminished over the three years from 24% in 2014 (SMR=1.24, 95% CI: 1.03, 1.45) to 17% in 2015 (SMR=1.17, 95% CI: 0.95, 1.39) and 10% in 2016 (SMR=1.10, 95% CI: 0.89, 1.31). Infants born at 22-23 weeks had a 23% higher mortality risk than expected (SMR=1.23, 95% CI: 1.02, 1.44). This excess mortality was almost wholly due to the infants who were not administered resuscitation. At this gestational age, 60% of infants were not administered resuscitation in Ireland, which is higher than for the VON population. Infants born at 24-27 weeks in a tertiary unit did not experience higher than expected mortality (SMR=1.01, 95% CI: 0.80, 1.23) but those born in non-tertiary units had a 70% higher mortality risk (SMR=1.70, 95% CI: 1.25, 2.15), most of which arose from those born in peripheral units. Infants born with a gestational age of at least 28 weeks did not have a higher mortality risk than expected (SMR=1.19, 95% CI: 0.90, 1.48).
All women anticipated to deliver at a gestational age of 23 weeks should be administered antenatal steroids and magnesium sulphate and the neonatology team should be alerted prior to delivery. Resuscitation should be administered to all infants born at 23 weeks who present in favourable condition i.e. without congenital anomaly, severely small for gestational age, severe hypoxia or severe infection. In line with the existing Model of Care for Neonatal Services in Ireland, infants born before reaching a gestational age of 28 weeks should ideally be delivered at one of the four tertiary neonatal units. The NPEC gratefully acknowledges the staff of 19 neonatal units in the country for their support in producing this report, and in particular, the commitment of those who co-ordinate the data collection process at unit level. We also thank the NICORE group and the team at the Vermont Oxford Network.