Outcome comparison of very preterm infants cared for in the neonatal intensive care units in Australia and New Zealand and in Canada

Aim: To compare risk-adjusted neonatal intensive care unit outcomes between regions of similar population demography and health-care systems in Australia-New Zealand and Canada to generate meaningful hypothesis for outcome improvements.

Methods: Retrospective study of data from preterm infants (<32 weeks gestational age) cared for in 29 ANZNN (Australian and New Zealand Neonatal Network) and 26 Canadian Neonatal Network (CNN) intensive care unit admitted between 2005 and 2007. Moribund infants or those with major congenital malformation were excluded. 

Results: The 9995 ANZNN infants had a higher gestational age (29 vs. 28 weeks, P < 0.0001), lower rate of outborn status (13.2% vs. 19.1%, P < 0.0001) and Apgar score <7 at 5-min (14.8% vs. 21.6%, P < 0.0001) than their 7141 CNN counterparts. After adjustment, ANZNN and CNN infants had a similar likelihood of survival (adjusted odds ratio (AOR) 1.01 (0.88, 1.16)), but ANZNN infants were at lower risk of severe retinopathy (AOR 0.71 (0.61, 0.83)), severe ultrasound neurological injury (AOR 0.68 (0.59, 0.78)), necrotising enterocolitis (AOR 0.65 (0.56, 0.76)), chronic lung disease (AOR 0.67 (0.62, 0.73)) and late-onset sepsis (AOR 0.83 (0.76, 0.91)). ANZNN infants were at a higher risk of pulmonary air leak (AOR 1.20 (1.01, 1.42)), early-onset sepsis (AOR 1.33 (1.02, 1.74)). More ANZNN infants received any respiratory support (AOR 1.27 (1.14, 1.41)) and continuous positive airway pressure as sole respiratory support (AOR 2.50 (2.27, 2.70)). 

Conclusions: Despite similarities in settings, ANZNN infants fared better in most measures. Outcome disparities may be related to differences in tertiary service provision, referral and clinical practices.