P90
STUDY OF ANTECEDENTS AND OUTCOMES OF SEVERE MORBIDITY IN NSW TERM NEONATES:
METHODOLOGICAL ASPECTS
Bajuk B, Sutton L, Sayer GP, Richardson V, Berry G, Henderson-Smart DJ
NICUS, NSW Centre for Perinatal Health Services Research, University of Sydney
There is inadequate information in the international literature about antecedents and outcomes of sick term neonates.
Preliminary data collected in New South Wales (NSW) and elsewhere suggest that term infants who require tertiary neonatal intensive care (NICU) are more likely than well term infants to have been exposed to a complicated antenatal course, and to have difficulty adjusting to their new environment once born. They have a higher mortality rate and may have a higher long term morbidity rate.
Aims: 1. Identify all sick full term neonates admitted to Neonatal Intensive Care Units (NICU’s) throughout NSW and a representative control group of well term neonates. 2. Determine associations between neonatal morbidities and socio-demographic, antenatal and perinatal factors in these infants. 3. Follow up both cases and controls, to describe the long term neurodevelopmental and sensory outcome in these children and their possible causal sequences.
Methods: Study design: Case-control with follow up at 1, 3 and 5 years. Study area: Babies born to mothers resident in the Sydney, Central Coast, Hunter, Illawarra, Central West and New England Health Areas. The study was approved by the 35 ethics committees in the study area. Cases: Singleton infants of gestational age >37 weeks born to mothers resident in NSW, without major congenital anomaly, not a planned home birth, mechanically ventilated for >4 hours and admitted to a tertiary NICU in NSW within the first 96 hours of life. Controls: As for cases, but not admitted to a tertiary NICU. Controls were collected independently of cases from a random sample of birth dates, generated from the 1994 NSW Midwives Data Collection for mothers resident at the time of the birth in the above health regions/areas. These birth dates were then applied prospectively to 1996 births, so that a control baby was one born in the same hospital as the 1994 baby on the date closest to that of the randomly selected 1994 baby, and closest in time to a randomly selected time of birth. If a control mother declined to take part in the study then the mother of the next closest baby born in that hospital was approached. This prospective method of control selection made it less likely to miss mothers on an early discharge program. Data were collected by the NICUS
Audit Officers (cases) and by designated liaison officers in the 57 obstetric hospitals involved in the study
(controls). Babies have been followed up at 12 months of age with a physical, neurological, developmental, vision and hearing examination by a paediatrician.
Results: Cases: 182 were approached, 174 agreed to participate, 19 died before hospital discharge, 5 died before 1 year of age, 1 died after 1 year and 3 have been unable to be contacted. Controls: 551 were approached, 448 agreed to participate, 1 excluded after discharge due to major congenital anomaly, 22 declined follow-up, 11 unable to contact. Overall 6% of cases and controls have been lost to follow-up at 1 year.
Conclusion: This study will provide the following unique information for Australia:- 1. Risk factors for major morbidity and mortality in full term neonates. 2. Prevalence of antenatal, perinatal and neonatal problems in well term infants. 3. Risk factors for major morbidity and disability in well and sick term infants at 1, 3 and 5 years. 4.
Risk factors for behavioural problems, and at 5 years factors associated with later learning problems in term infants.
5. Norms for a representative population of Australian 1 year olds for the Griffiths (revised) Developmental
Assessment.