Prenatal predictors of chronic lung disease in very preterm infants.

OBJECTIVE: To identify prenatal risk factors for chronic lung disease (CLD) at 36 weeks postmenstrual age in very preterm infants. POPULATION: Data were collected prospectively as part of the ongoing audit of the Australian and New Zealand Neonatal Network (ANZNN) of all infants born at less than 32 weeks gestation admitted to all tertiary neonatal intensive care units in Australia and New Zealand. METHODS: Prenatal factors up to 1 minute of age were examined in the subset of infants born at gestational ages 22-31 weeks during 1998-2001, and who survived to 36 weeks postmenstrual age (n = 11 453). Factors that were significantly associated with CLD at 36 weeks were entered into a multivariate logistic regression model. RESULTS: After adjustment, low gestational age was the dominant risk factor, with an approximate doubling of the odds with each week of decreasing gestational age from 31 to less than 25 weeks (trend p<0.0001). Birth weight for gestational age also had a dose-response effect: the lower the birth weight for gestational age, the greater the risk, with infants below the third centile having 5.67 times greater odds of CLD than those between the 25th and 75th centile (trend p<0.0001). There was also a significantly increased risk for male infants (odds ratio 1.51 (95% confidence interval 1.36 to 1.68), p<0.0001). CONCLUSIONS: These population based data show that the prenatal factors low gestational age, low birth weight for gestational age, and male sex significantly predict the development of chronic respiratory insufficiency in very preterm infants and may assist clinical decision about delivery.

Variation in rates of severe retinopathy of prematurity among neonatal intensive care units in the Australian and New Zealand Neonatal Network.

AIM: To analyse variations in rates of severe retinopathy of prematurity (ROP) among neonatal intensive care units (NICUs) in the Australian and New Zealand Neonatal Network (ANZNN), adjusting for sampling variability and for case mix. METHODS: 25 NICUs were included in the study of 2105 infants born at less than 29 weeks in 1998 and 1999, who survived to 36 weeks post-menstrual age and were examined for ROP. The observed NICU rates of severe ROP were adjusted for case mix using logistic regression on gestation, weight for gestational age and sex, and for sampling variability using shrinkage estimates. The corrected rate in the best 20% of NICUs was identified and NICU variations in rates were compared with those in 2000-1. RESULTS: The overall (unadjusted) rate of severe ROP in the NICUs was 9.6% (interquartile range 5.4-12.8%). After adjusting for both case mix and sampling variability there remained significant variation among the NICUs. 20% of NICUs had a rate of severe ROP

Outcomes for high risk New Zealand newborn infants in 1998-1999: a population based, national study.

OBJECTIVE: To determine short term morbidity and mortality outcomes, provision of care, and treatments for a national cohort of high risk infants born in 1998-1999 and admitted to New Zealand neonatal intensive care units (NICUs). SETTING: All level III (six) and level II (13) NICUs in New Zealand. METHODS: Prospective audit by the Australian and New Zealand Neonatal Network (ANZNN) of all infants defined as "high risk" (born at < 32 weeks gestation or < 1500 g birth weight, or received assisted ventilation for four hours or more, or had major surgery). Data were collected from birth until discharge home or death. RESULTS: There were 3368 high risk infants (3.0% of all live births), comprising 1241 (37%) < 32 weeks gestation, 1084 (32%) < 1500 g, 3156 (94%) who received assisted ventilation, and 243 (7%) who received major surgery (categories overlap). Most infants (87%) received some care in tertiary hospitals, and 13% were cared for entirely in non-tertiary hospitals. Survival was 91% for infants < 32 weeks gestation, 97% for infants > or = 32 weeks gestation who received assisted ventilation, and 92% for infants > or = 32 weeks gestation who had major surgery. The proportion of very preterm infants who survived free of early major morbidity was 11%, 28%, 53%, 81%, and 90% for infants born at < 24, 24-25, 26-27, 28-29, and 30-31 weeks gestation respectively. CONCLUSIONS: These unique population based national data provide contemporary information on the care and early morbidity and mortality outcomes for all high risk infants, whether cared for in hospitals with level III or level II NICUs.

Improved outcomes for very low birthweight infants: evidence from New Zealand national population based data.

OBJECTIVE: To compare the survival and short term morbidity of all New Zealand very low birthweight (VLBW) infants born in two epochs, 1986 and 1998-1999. SETTING: All level III and level II neonatal intensive care units (NICUs) in New Zealand. METHODS: In 1986, data were prospectively collected for a study of retinopathy of prematurity (ROP). In 1998-1999, prospective data were collected by the Australian and New Zealand Neonatal Network (ANZNN). Both cohorts included all VLBW infants born during the calendar year and admitted to a NICU. Data were collected from birth until discharge home or death. RESULTS: More VLBW infants were admitted for care in 1998-1999 (n = 1084, 0.96% of livebirths) than in 1986 (n = 413, 0.78% of livebirths; p < 0.001), including a higher proportion of VLBW infants of < 1000 g birth weight (38% v 32% respectively; p < 0.05). Survival to discharge home increased from 81.8% in 1986 to 90.3% in 1998-1999 (p < 0.001). The 1998-1999 cohort had a higher proportion of infants born in a hospital with a level III NICU (87% v 72% in 1986; p < 0.001) and receiving antenatal corticosteroids (80% v 58% in 1986; p < 0.001). In 1998-1999, the incidence of several morbidities had decreased compared with 1986, including oxygen dependency at 28 days (29% v 39% respectively; p = 0.001) and at 36 weeks postmenstrual age (16% v 23%; p = 0.002), grade 1 intraventricular haemorrhage (IVH) (8% v 24%; p < 0.001), grade 2/3 IVH (5% v 11%; p < 0.001), and stage 3/4 ROP for infants < 1000 g (6% v 13%; p < 0.001). CONCLUSIONS: The outlook for VLBW infants in New Zealand has improved since 1986.

Use of systematic reviews of randomised trials by Australian neonatologists and obstetricians.

OBJECTIVE: To determine what proportion of Australian neonatologists and obstetricians report using systematic reviews of randomised trials. DESIGN: Cross-sectional survey using structured telephone interviews. SETTING: Australian clinical practice in 1995. PARTICIPANTS: 103 of the 104 neonatologists in Australia (defined as clinicians holding a position in a neonatal intensive care unit); a random sample of 145 members of the Royal Australian College of Obstetricians and Gynaecologists currently practising in Australia. MAIN OUTCOME MEASURES: Information sources used in clinical practice; reported awareness of, access to and use of systematic reviews, and consequent practice changes. RESULTS: Response rates were 95% (neonatologists) and 87% (obstetricians); 71 neonatologists (72%) and 55 obstetricians (44%) reported using systematic reviews, primarily for individual patient care. Databases of systematic reviews were used with a median frequency of once per month. Among neonatologists, systematic reviews were used more commonly by those who were familiar with computers, attended professional meetings, and had authored research papers. Among obstetricians, they were used more commonly by those who were familiar with computers, had less than 10 years' clinical experience, attended more deliveries, and were full-time staff specialists in public hospitals. Of neonatologists who reported using systematic reviews, 58% attributed some practice change to this use. For obstetricians, the corresponding figure was 80%. CONCLUSIONS: There is evidence that Australian neonatologists and obstetricians use systematic reviews and modify their practice accordingly. Dissemination efforts can benefit from knowledge of factors that predict use of systematic reviews.