Risk adjusted and population based studies of the outcome for high risk infants in Scotland and Australia

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Abstract
OBJECTIVES To compare outcomes of care in selected neonatal intensive care units (NICUs) for very low birthweight (VLBW) or preterm infants in Scotland and Australia (study 1) and perinatal care for all VLBW infants in both countries (study 2). DESIGN Study 1: risk adjusted cohort study; study 2: population based cohort study. SUBJECTS Study 1: all 2621 infants of < 1500 g birth weight or < 31 weeks' gestation admitted to a volunteer sample of hospitals comprising eight of all 17 Scottish NICUs and six of all 12 tertiary NICUs in New South Wales and Queensland in 1993–1994; study 2: all 5986 infants of 500–1499 g birth weight registered as live born in Scotland and Australia in 1993–1994. MAIN OUTCOMES Study 1: (a) hospital death; (b) death or cerebral damage, each adjusted for gestation and CRIB (clinical risk index for babies); study 2: neonatal (28 day) mortality. RESULTS Study 1. Data were obtained for 1628 admissions in six Australian NICUs, 775 in five Scottish tertiary NICUs, and 148 in three Scottish non-tertiary NICUs. Crude hospital death rates were 13%, 22%, and 22% respectively. Risk adjusted hospital mortality was about 50% higher in Scottish than in Australian NICUs (adjusted mortality ratio 1.46, 95% confidence interval (CI) 1.29 to 1.63, p < 0.001). There was no difference in risk adjusted outcomes between Scottish tertiary and non-tertiary NICUs. After risk adjustment, death or cerebral damage was more common in Scottish than Australian NICUs (odds ratio 1.9, 95% CI 1.5 to 2.5). Both these risk adjusted adverse outcomes remained more common in Scottish than Australian NICUs after excluding all infants < 28 weeks' gestation from the comparison. Study 2. Population based neonatal mortality in infants of 500–1499 g was higher in Scotland (20.3%) than Australia (16.6%) (relative risk 1.22, 95% CI 1.08 to 1.39, p = 0.002). In a post hoc analysis, neonatal mortality was also higher in England and Wales than in Australia. CONCLUSIONS Study 1: outcome was better in the Australian NICUs. Study 2: perinatal outcome was better in Australia. Both results may be consistent, at least in part, with differences in the organisation and implementation of neonatal care.