'Joining the Dots: Linking Prenatal Drug Exposure to Childhood and Adolescence' - research protocol of a population cohort study

INTRODUCTION

Prenatal drug exposure (PDE) is one of the most important causes of child harm, but comprehensive information about the long-term outcomes of the families is difficult to ascertain. The Joining the Dots cohort study uses linked population data to understand the relationship between services, therapeutic interventions and outcomes of children with PDE.

METHODS AND ANALYSIS

Information from routinely collected administrative databases was linked for all births registered in New South Wales (NSW), Australia between 1 July 2001 and 31 December 2020 (n=1 834 550). Outcomes for seven mutually exclusive groups of children with varying prenatal exposure to maternal substances of addiction, including smoking, alcohol, prescription/illicit drugs and neonatal abstinence syndrome will be assessed. Key exposure measures include maternal drug use type, maternal social demographics or social determinants of health, and maternal physical and mental health comorbidities. Key outcome measures will include child mortality, academic standardised testing results, rehospitalisation and maternal survival. Data analysis will be conducted using Stata V.18.0.

ETHICS AND DISSEMINATION

Approvals were obtained from the NSW Population and Health Services Research Ethics Committee (29 June 2020; 2019/ETH12716) and the Australian Capital Territory Health Human Research Ethics Committee (11 October 2021; 2021-1231, 2021-1232, 2021-1233); and the Aboriginal Health and Medical Research Council (5 July 2022; 1824/21), and all Australian educational sectors: Board of Studies (government schools), Australian Independent Schools and Catholic Education Commission (D2014/120797). Data were released to researchers in September 2022. Results will be presented in peer-reviewed academic journals and at international conferences. Collaborative efforts from similar datasets in other countries are welcome.

Neurodevelopmental outcomes of extremely preterm infants with bronchopulmonary dysplasia (BPD) - A retrospective cohort study

OBJECTIVE

To investigate the neurodevelopmental outcomes for preterm infants born < 29 weeks gestation with/without bronchopulmonary dysplasia (BPD).

STUDY DESIGN

Preterm infants < 29 weeks' gestation born 2007-2018 in New South Wales and the Australian Capital Territory, Australia, were included. Infants who died < 36 weeks' postmenstrual age and those with major congenital anomalies were excluded. Subjects were assessed at 18-42 months corrected age using the Bayley Scales of Infant Development, 3rd edition.

RESULTS

1436 infants without BPD (non-BPD) and 1189 infants with BPD were followed. The BPD group, 69 % infants were discharged without respiratory support (BPD1), 29 % on oxygen (BPD2) and 2 % on pressure support/tracheostomy (BPD3). Moderate neurodevelopmental impairment (NDI) was evident in 5.7 % of non-BPD infants, 11 % BPD1, 15 % BPD2, 15 % BPD3 infants. Severe NDI was seen in 1.7 % non-BPD infants, 3.4 % BPD1, 7.3 % BPD2, 35 % BPD3 infants. After adjusting for confounders, infants with BPD2 (OR 2.24, 99.9 % CI 1.25 to 5.77) or BPD3 (OR 5.99, 99.9 % CI 1.27 to 46.77) were more likely to have moderate-severe NDI compared to non-BPD infants.

CONCLUSION

The majority of infants with BPD were discharged home without respiratory support and had better neurocognitive outcomes in early childhood compared to those that required home-based oxygen or respiratory support.

Symptomatic Postnatal Cytomegalovirus Infection in Less than 32-Week Preterm Infants: 13-Year Retrospective Multicenter Case-Control Study

INTRODUCTION

Reports on the influence of postnatal cytomegalovirus (pCMV) infection in neonatal outcomes of preterm babies vary while guidance on management including screening is lacking. We aim to determine the association between symptomatic pCMV infection and chronic lung disease (CLD) and mortality in preterm infants born less than 32 weeks gestation.

METHODS

We used data from the Neonatal Intensive Care Units' (NICUS) population-based prospective data registry of infants in 10 neonatal units in New South Wales and the Australian Capital Territory, Australia. De-identified perinatal and neonatal outcome data for 40,933 infants were examined. We identified 172 infants <32 weeks gestation with symptomatic pCMV infection. Each was matched with one control infant.

RESULTS

Infants with symptomatic pCMV infection were 2.7 times more likely to develop CLD (OR 2.7, 95% CI: 1.7-4.5) and spend 25.2 days more in hospital (95% CI: 15.2-35.2). Seventy-five percent (129/172) of infants with symptomatic pCMV were extremely preterm (<28 weeks). The mean age of symptomatic pCMV diagnosis was 62.5 ± 20.5 days or 34.7 ± 3.6 weeks-corrected gestational age. Ganciclovir treatment did not decrease CLD and death. CLD was 5.5 times predictive of death in patients with symptomatic pCMV infection. Symptomatic pCMV infection did not influence mortality nor increase neurologic impairment.

CONCLUSION

Symptomatic pCMV is a modifiable factor affecting extreme preterm infants with significant impact on CLD. Prospective study on screening and treatment will help unveil potential benefits in our already at-risk preterm infants.

Variation in hospital morbidities in an Australian neonatal intensive care unit network

OBJECTIVE

There is an expectation among the public and within the profession that the performance and outcome of neonatal intensive care units (NICUs) should be comparable between centres with a similar setting. This study aims to benchmark and audit performance variation in a regional Australian network of eight NICUs.

DESIGN

Cohort study using prospectively collected data.

SETTING

All eight perinatal centres in New South Wales and the Australian Capital Territory, Australia.

PATIENTS

All live-born infants born between 23⁺⁰ and 31⁺⁶ weeks gestation admitted to one of the tertiary perinatal centres from 2007 to 2020 (n=12 608).

MAIN OUTCOME MEASURES

Early and late confirmed sepsis, intraventricular haemorrhage, medically and surgically treated patent ductus arteriosus, chronic lung disease (CLD), postnatal steroid for CLD, necrotising enterocolitis, retinopathy of prematurity (ROP), surgery for ROP, hospital mortality and home oxygen.

RESULTS

NICUs showed variations in maternal and neonatal characteristics and resources. The unadjusted funnel plots for neonatal outcomes showed apparent variation with multiple centres outside the 99.8% control limits of the network values. The hierarchical model-based risk-adjustment accounting for differences in patient characteristics showed that discharged home with oxygen is the only outcome above the 99.8% control limits.

CONCLUSIONS

Hierarchical model-based risk-adjusted estimates of morbidity rates plotted on funnel plots provide a robust and straightforward visual graphical tool for presenting variations in outcome performance to detect aberrations in healthcare delivery and guide timely intervention. We propose using hierarchical model-based risk adjustment and funnel plots in real or near real-time to detect aberrations and start timely intervention.

Are we enrolling representative cohorts of premature infants in our clinical trials?

OBJECTIVE

To compare the difference in outcomes in a subset population of infants "eligible but not enrolled; ENE" vs those who were "eligible and enrolled, EE" in The Australian Placental Transfusion Study (APTS).

STUDY DESIGN

Population-based multicentre retrospective cohort study.

RESULTS

A total of 535 (17.7%) infants were categorized as EE and 2489 (82.3%) ENE. ENE infants were significantly more premature (mean gestation 27.0 vs 28.0 weeks) but otherwise of similar anthropometric measures compared to EE infants. ENE infants had significantly higher incidences of low Apgar scores <7 at 5 min, CLD, IVH and PDA requiring treatment. Using a multivariate adjusted-analysis, ENE were at a greater risk for mortality (OR 1.86; 95% CI, 1.30-2.67, p < 0.001).

CONCLUSION

Antenatal consenting may lead to biased population representation, which may affect trial results' generalizability. Retrospective consent or waiver of consent may improve the generalizability of neonatal and emergency clinical trials.

Characteristics and causes of death in children with neonatal abstinence syndrome

AIM

To determine characteristics of death in children with neonatal abstinence syndrome (NAS).

METHODS

A population-based linkage study of children from birth to 13 years of age in New South Wales (NSW), Australia, born 1 July 2000 to 31 December 2011. Infants with an International Statistical Classification of Diseases and Related Problems, Australian modification coding of NAS (P96.1, n = 3842) were compared to infants (n = 1 018 421) without NAS by birth, hospitalisation and death records linkage.

RESULTS

Forty-five (1.2%) children with NAS died, compared to 3665 (0.4%) other children. Most deaths (n = 30, 66%) in NAS children occurred between 1 month and 1 year. Risk of death was independently increased in full-term children (hazard ratio 2.34, 95% confidence interval 1.63-3.35; P < 0.001) from lower socio-economic groups (1.23, 1.12-1.35; P < 0.001), most commonly from ill-defined or external causes, including assault and accidents (P < 0.001).

CONCLUSIONS

Children with NAS, especially those of term gestation and from lower socio-economic groups, are more likely to die, especially from external causes.

Association of Age at First Severe Respiratory Syncytial Virus Disease With Subsequent Risk of Severe Asthma: A Population-Based Cohort Study

OBJECTIVE

In a population-based cohort study, we determined the association between the age at first severe respiratory syncytial virus (RSV) disease and subsequent asthma.

METHODS

Incidence rates and rate ratios of the first asthma-associated hospitalization after 2 years of age in children hospitalized for RSV disease at <3 months, 3 to <6 months, 6 to <12 months, and 12-24 months of age were calculated.

RESULTS

The incidence of asthma-associated hospitalization per 1000 child-years among children hospitalized for RSV disease at <3 months of age was 0.5 (95% confidence interval [CI], .2-.7); at 3 to <6 months of age, 0.9 (95% CI,.5-1.3); at 6 to <12 months of age, 2.0 (95% CI, 1.4-2.7); and at 12-24 months of age, 1.7 (95% CI, 1.0-2.5). The rate ratio of hospitalization for asthma was 2-7-fold greater among children hospitalized for RSV disease at ages ≥6 months than that among those hospitalized for RSV disease at ages 0 to <6 months.

CONCLUSIONS

Although the burden of RSV disease is highest in children aged <6 months, the burden of subsequent asthma is higher in children who develop RSV disease at ages ≥6 months.

Neurodevelopmental outcomes of extremely preterm infants in New South Wales and the Australian Capital Territory

AIM

This study aimed to provide updated information on gestation-specific neurodevelopmental outcomes of extremely to very preterm infants 23-28 weeks' gestation admitted to neonatal intensive care units (NICUs).

METHODS

This was a population-based retrospective cohort study of infants born between 23⁺⁰ and 28⁺⁶ weeks' gestation and admitted to a network of NICUs between 2007 and 2012 in a well-defined geographic area of New South Wales (NSW) and the Australian Capital Territory (ACT). Primary outcome was moderate to severe neurodevelopmental impairment.

RESULTS

Of 2287 infants admitted to NICUs, 1914 (83.7%) survived to discharge, and 1514 (79.8% = 1514/1897) were followed up. Moderate to severe neurodevelopmental impairment was 11% overall, and the incidence decreased with increasing gestational age (GA): 25, 23, 15, 13, 9 and 7% at 23, 24, 25, 26, 27 and 28 weeks, respectively. Male gender, major intraventricular haemorrhage, late-onset sepsis, chronic lung disease and post-natal corticosteroid therapy were found to be independently associated with increased risk of moderate to severe impairment. Compared with an incidence of 16% in the 1998-2004 cohort, there was a significant reduction in moderate to severe neurodevelopmental impairment in the current cohort (unadjusted odds ratio: 0.65, 95% confidence interval: 0.52-0.80).

CONCLUSIONS

We report the latest neurodevelopmental outcomes of extremely to very preterm infants in NSW and the ACT. Neurodevelopmental outcome rates based on GA alone may not provide the true estimate as these outcomes can vary based on the presence or absence of other relevant perinatal factors.

Active care of infants born between 22 and 26 weeks of gestation does not follow consensus expert recommendations

AIM

To determine the relationship between clinical practice and publication of an Australian consensus statement for management of extremely preterm infants in 2006.

METHODS

A population-based study using linked data from New South Wales, Australia for births between 22 + 0 and 26 + 6 weeks of gestation between 2000 and 2011.

RESULTS

There were 4746 births of whom 2870 were liveborn and 1876 were stillborn. Of the live births, 2041 (71%) were resuscitated, 1914 (67%) were admitted into a neonatal intensive care unit (NICU) and 1310 (46%) survived to hospital discharge. Thirty-nine (2%) stillbirths were resuscitated but none survived. No 22-week infant survived to hospital discharge. Fewer 23-week gestation infants were resuscitated between 2004 (52%) and 2005 (20%) but resuscitation rates increased by 2008 (44%). There was no difference at other gestations. Adjusted odds ratio (OR) for resuscitation was increased by birthweight (OR: 1.01), tertiary hospital birth (OR: 3.4) and Caesarean delivery (OR: 11.3) and decreased by rural residence (OR: 0.4) and male gender (OR: 0.7).

CONCLUSION

Expert recommendations may be shaped by clinical practice rather than the converse, especially for 23-week gestation infants. Recommendations should be revised regularly to include clinical practice changes.

Long-term outcomes after group B streptococcus infection: a cohort study

OBJECTIVE

To describe the risk of death and hospitalisation until adolescence of children after group B streptococcus (GBS) infection during infancy.

DESIGN

Population-based cohort study.

SETTING

New South Wales, Australia.

PATIENTS

All registered live births from 2000 to 2011.

INTERVENTIONS

Comparison of long-term outcomes in children with the International Statistical Classification of Diseases and Related Health Problems-10th Revision discharge codes corresponding to GBS infections and those without.

MAIN OUTCOME MEASURES

Death and hospitalisation.

RESULTS

A total of 1206 (0.1%) children (936 (77.6%)≥37 weeks' gestation) were diagnosed with GBS infection. Over the study period, infection rates decreased from 2.1 (95% CI 1.8 to 2.4) to 0.7 (95% CI 0.5 to 0.9) per 1000 live births. Infants with GBS infection were born at lower gestation (mean 37.6 vs 39.0 weeks), were more likely very low birth weight (<1500 g, OR 9.1(95% CI 7.4 to 11.3)), born premature (OR 3.9(95% CI 3.4 to 4.5)) and have 5 min Apgar scores ≤5 (OR 6.7(95% CI 5.1 to 8.8)). Children with GBS had three times the adjusted odds of death (adjusted OR (AOR) 3.0(95% CI 2.1 to 4.3)) or rehospitalisations (AOR 3.1(95% CI 2.7 to 3.5)). Thirty-six (3.0%) with GBS died, with >50% of deaths occurring <28 days. Children with GBS were hospitalised more frequently (median 2 vs 1), for longer duration (mean 3.7 vs 2.2 days) and were at higher risk for problems with genitourinary (OR 3.1(95% CI 2.8 to 3.5)) and nervous (OR 2.0 (95% CI1.7 to 2.3)) systems.

CONCLUSIONS

Despite decreasing GBS rates, the risk of poor health outcomes for GBS-infected children remains elevated, especially during the first 5 years. Survivors continue to be at increased risk of death and chronic conditions requiring hospitalisations, such as cerebral palsy and epilepsy.

Admission temperature and hospital outcomes in extremely preterm infants

AIM

To evaluate trends in admission temperature and its effect on mortality and short-term morbidities in extremely preterm infants.

METHODS

A regional cohort study of infants born at 23-28 weeks' gestation and admitted to the 10 neonatal intensive care units in New South Wales and the Australian Capital Territory between 1994 and 2012. Hypothermia was defined as skin temperature <36°C on admission to the neonatal intensive care unit. The primary outcome was hospital mortality.

RESULTS

In total, 6267 infants were included. Mean admission temperatures improved significantly from 35.6°C in 1994 to 36.4°C in 2012 (R < 0.88). The incidence of hypothermia was 29.5 and 13.9% between 1994-2005 and 2006-2012, respectively. In comparison with normothermic infants, hypothermic infants had lower gestational age at birth (26 vs. 27 weeks) and lower birthweight (800 vs. 976 g). In-hospital mortality was higher in hypothermic infants (28.5 vs. 12.9%; odds ratio (OR) 2.69, 95% confidence interval (CI) 2.37-3.06). Severe intraventricular haemorrhage (12.1 vs. 8.5%, OR 1.48, 95% CI 1.25-1.75), necrotising enterocolitis (NEC) (11.0 vs. 7.5%; OR 1.54, 95% CI 1.29-1.83) and severe retinopathy of prematurity (16.5 vs. 8.9%; OR 2.02, 95% CI 1.70-2.39) were significantly higher in hypothermic infants. Multivariate regression analysis showed hypothermia was an independent risk factor for increased mortality (AOR (adjusted odds ratio ) 1.50, 95% CI 1.29-1.74, P < 0.001) and NEC (AOR 1.28, 95% CI 1.05-1.55, P = 0.01).

CONCLUSIONS

Admission temperatures improved during the time period. Hypothermia at admission was associated with a significant increase in mortality and NEC.

Impact of influenza on hospitalization rates in children with a range of chronic lung diseases

BACKGROUND

Data on burden of severe influenza in children with a range of chronic lung diseases (CLDs) remain limited.

METHOD

We performed a cohort study to estimate burden of influenza-associated hospitalization in children with CLDs using population-based linked data. The cohort comprised all children in New South Wales, Australia, born between 2001 and 2010 and was divided into five groups, children with: (a) severe asthma; (b) bronchopulmonary dysplasia (BPD); (c) cystic fibrosis (CF); (d) other congenital/chronic lung conditions; and (e) children without CLDs. Incidence rates and rate ratios for influenza-associated hospitalization were calculated for 2001-2011. Average cost/episode of hospitalization was estimated using public hospital cost weights.

RESULTS

Our cohort comprised 888 157 children; 11 058 (1.2%) had one of the CLDs. The adjusted incidence/1000 child-years of influenza-associated hospitalization in children with CLDs was 3.9 (95% CI: 2.6-5.2) and 0.7 (95% CI: 0.5-0.9) for children without. The rate ratio was 5.4 in children with CLDs compared to children without. The adjusted incidence/1000 child-years (95% CI) in children with severe asthma was 1.1 (0.6-1.6), with BPD was 6.0 (3.7-8.3), with CF was 7.4 (2.6-12.1), and with other congenital/chronic lung conditions was 6.9 (4.9-8.9). The cost/episode (95% CI) of influenza-associated hospitalization was AUD 19 704 (95% CI: 11 715-27 693) for children with CLDs compared to 4557 (95% CI: 4129-4984) for children without.

DISCUSSION

This large population-based study suggests a significant healthcare burden associated with influenza in children with a range of CLDs.

Treatment with nitric oxide in the neonatal intensive care unit is associated with increased risk of childhood cancer

AIM

This study aimed to determine whether neonatal intensive care therapies increase the risk of carcinogenesis in childhood.

METHODS

This study used population-based data on 1 072 957 infants born in New South Wales, Australia, between 2000 and 2011 and multivariate logistic regression to examine any associations between therapies used in the neonatal intensive care unit and diagnoses of cancer until mid 2012.

RESULTS

A total of 1126 of 1 072 957 (0.1%) children were diagnosed with cancer. Cancer risk was significantly increased by preterm birth (gestation <37 weeks; adjusted odds ratio (aOR) 1.3 (95% confidence interval: 1.0-1.6), birth weight ≥4 kg (aOR 1.4, 1.2-1.6) and caesarean delivery (aOR 1.2, 1.1-1.4). Extremely preterm (<28 weeks of gestation) infants were more likely to develop hepatic tumours (aOR 12.7, 3.3-48.3) than term infants. The only therapy used in the neonatal intensive care that was independently associated with an increased risk of cancer was nitric oxide (aOR 8.6, 4.3-17.4). Eight of the 790 (1%) infants treated with nitric oxide developed cancer (gestation range 30-41 weeks, age of cancer diagnosis: four months-five years).

CONCLUSION

Treatment with nitric oxide was associated with a higher risk of childhood cancer. These findings require further research.

Variation in hospital mortality in an Australian neonatal intensive care unit network

BACKGROUND

Studying centre-to-centre (CTC) variation in mortality rates is important because inferences about quality of care can be made permitting changes in practice to improve outcomes. However, comparisons between hospitals can be misleading unless there is adjustment for population characteristics and severity of illness.

OBJECTIVE

We sought to report the risk-adjusted CTC variation in mortality among preterm infants born <32 weeks and admitted to all eight tertiary neonatal intensive care units (NICUs) in the New South Wales and the Australian Capital Territory Neonatal Network (NICUS), Australia.

METHODS

We analysed routinely collected prospective data for births between 2007 and 2014. Adjusted mortality rates for each NICU were produced using a multiple logistic regression model. Output from this model was used to construct funnel plots.

RESULTS

A total of 7212 live born infants <32 weeks gestation were admitted consecutively to network NICUs during the study period. NICUs differed in their patient populations and severity of illness.The overall unadjusted hospital mortality rate for the network was 7.9% (n=572 deaths). This varied from 5.3% in hospital E to 10.4% in hospital C. Adjusted mortality rates showed little CTC variation. No hospital reached the +99.8% control limit level on adjusted funnel plots.

CONCLUSION

Characteristics of infants admitted to NICUs differ, and comparing unadjusted mortality rates should be avoided. Logistic regression-derived risk-adjusted mortality rates plotted on funnel plots provide a powerful visual graphical tool for presenting quality performance data. CTC variation is readily identified, permitting hospitals to appraise their practices and start timely intervention.

Influence of early childhood burns on school performance: an Australian population study

OBJECTIVES

To determine the influence of burn injuries on childhood performance in national standardised curriculum-based school tests.

DESIGN

Birth and health records of 977 children who were hospitalised with a burn injury between 2000 and 2006 in the state of New South Wales, Australia, were linked to performance scores in the National Assessment Program: Literacy and Numeracy test, a compulsory nationwide curriculum-based test (CBT) and compared with children who were not hospitalised for burns and who were matched for birth year, gender, gestation and socioeconomic status.

MAIN OUTCOME MEASURES

Test scores in years 3 (ages 8-9), 5 (ages 10-11) and 7 (ages 13-14) in numeracy, writing, reading, spelling, grammar and punctuation.

RESULTS

Mean age at first burn injury was 28 months (median: 20, range: 0-140). Children with burns were significantly more likely to have younger mothers (28.5 vs 29.6 years) (P<0.001), be indigenous (OR 2.5 (95% CI 2.1 to 3.1)) (P<0.001) and have siblings (OR 1.2 (95% CI 1.1 to 1.4)) (P<0.001). They were also less likely to meet national minimum standards in most domains of testing until year 5, even after adjustment for parental education levels, parental smoking, maternal age and indigenous status. Each 10% increase in total body surface area burnt was associated with a decrease in year 5 scores by 37.0% in numeracy and 71.9% in writing.

CONCLUSIONS

Most childhood burn injuries occur before the start of formal schooling. Children who are hospitalised for burns perform more poorly in CBT even after accounting for family and socioeconomic disadvantage. Rehabilitation of children with burn injuries must address school performance to decrease any long-term negative societal impact of burns.

Association between respiratory syncytial viral disease and the subsequent risk of the first episode of severe asthma in different subgroups of high-risk Australian children: a whole-of-population-based cohort study

OBJECTIVE

To determine the contribution of respiratory syncytial virus (RSV) to the subsequent development of severe asthma in different subgroups of children at risk of severe RSV disease.

SETTINGS

The study was conducted in New South Wales (NSW), Australia.

PARTICIPANTS

The study comprised all children born in NSW between 2000 and 2010 with complete follow-up till 31 December 2011. The cohort was divided into three subgroups: (1) non-Indigenous high-risk children: non-Indigenous children born preterm or born with a low birth weight; (2) Indigenous children: children of mothers whose Indigenous status was recorded as Aboriginal and/or Torres Strait Islander and (3) non-Indigenous standard risk children: all other non-Indigenous term children.

PRIMARY OUTCOME MEASURE

Risk of development of severe asthma in different subgroups of children who had RSV hospitalisation in the first 2 years of life compared with those who did not.

DESIGN

We performed a retrospective cohort analysis using population-based linked administrative data. Extended Cox model was used to determine HR and 95% CI around the HR for first asthma hospitalisation in different subgroups of children.

RESULTS

The cohort comprised 847 516 children born between 2000 and 2010. In the adjusted Cox model, the HR of first asthma hospitalisation was higher and comparable across all subgroups of children who had RSV hospitalisation compared with those who did not. The HR (95% CI) was highest in children aged 2-3 years; 4.3 (95% CI 3.8 to 4.9) for high-risk, 4.0 (95% CI 3.3 to 4.8) for Indigenous and 3.9 (95% CI 3.7 to 4.1) for non-Indigenous standard risk children. This risk persisted beyond 7 years of age.

CONCLUSION

This large study confirms a comparable increased risk of first asthma hospitalisation following RSV disease in the first 2 years of life across different subgroups children at risk.

Dwell time and risk of central-line-associated bloodstream infection in neonates

BACKGROUND

Umbilical venous catheters (UVCs) or peripherally inserted central catheters (PICCs), widely used in high-risk neonates, may have a threshold dwell time for subsequent increased risk of central-line-associated bloodstream infection (CLABSI).

AIM

To evaluate the CLABSI risks in neonates having either UVC, PICC, or those having both sequentially.

METHODS

The study included 3985 infants who had UVC or PICC inserted between 2007 and 2009 cared for in 10 regional neonatal intensive care units: 1392 having UVC only (group 1), 1317 PICC only (group 2), and 1276 both UVC and PICC (group 3).

FINDINGS

There were 403 CLABSIs among 6000 venous catheters inserted, totalling 43,302 catheter-days. CLABSI rates were higher in group 3 infants who were of lowest gestation (16.9 per 1000 UVC-days and 12.5 per 1000 PICC-days; median: 28 weeks) when compared with group 1 (3.3 per 1000 UVC-days; 37 weeks) and group 2 (4.8 per 1000 PICC-days; 30 weeks). Life table and Kaplan-Meier hazard analysis showed that UVC CLABSI rate increased stepwise to 42 per 1000 UVC-days by day 10, with the highest rate in group 3 (85 per 1000 UVC-days). PICC CLABSI rates remained relatively stable at 12-20 per 1000 PICC-days. Compared to PICC, UVC had a higher adjusted CLABSI risk controlled for dwell time. Among group 3, replacing UVC electively before day 4 may have a trend of lower CLABSI risk than late replacement.

CONCLUSION

There was no cut-off duration beyond which PICC should be removed electively. Early UVC removal and replacement by PICC before day 4 might be considered.

Eligibility criteria for therapeutic hypothermia: From trials to clinical practice

AIM

Whole body therapeutic hypothermia (TH) for hypoxic ischaemic encephalopathy was introduced into clinical practice in New South Wales (NSW) and Australian Capital Territory in 2007. State-wide policy adopting the eligibility criteria and practice based on trial-designs was published in 2009.

METHODS

The study was conducted by retrospectively reviewing medical records of all TH infants born between 2007 and 2011 in NSW and Australian Capital Territory to examine if eligibility criteria (assessed against evidence-based policy directives) were met.

RESULTS

A total of 207 infants received TH, 104 (50%) did not meet the eligibility criteria defined in NSW policy directive. Over the 5-year period, the proportion of infants meeting the eligibility criteria did not change. Seventy percent of infants (73 out of 104) not meeting eligibility criteria did not fulfil the criteria for 'evidence of asphyxia', although half of them met 'moderate or severe encephalopathy criterion'. Adverse events (hypotension, coagulopathy and arrhythmia), were more common in the 'criteria met' group than the 'criteria not met' group (89 vs. 71%, P = 0.001). Similar proportions of infants had TH discontinued before 72 h (criteria met: 32 (31%) vs. criteria not met: 27(26%)). Most frequent reason for early cessation was 'palliation' (19/32, 59%) in criteria met and 'clinical improvement' (16/27, 59%) in criteria not met group.

CONCLUSIONS

Many TH infants were treated based on clinician judgement, though not meeting the trial-design policy criteria. Early TH cessation (<72 h) was common. Future studies are warranted on long-term neurodevelopmental outcomes for all infants receiving TH particularly those with early cessation of therapy.

Causes of death in very preterm infants cared for in neonatal intensive care units: a population-based retrospective cohort study

Background

While there are good data to describe changing trends in mortality and morbidity rates for preterm populations, there is very little information on the specific causes and pattern of death in terms of age of vulnerability. It is well established that mortality increases with decreasing gestational age but there are limited data on the specific causes that account for this increased mortality. The aim of this study was to establish the common causes of hospital mortality in a regional preterm population admitted to a neonatal intensive care unit (NICU).

Methods

Retrospective analysis of prospectively collected data of the Neonatal Intensive Care Units' (NICUS) Data Collection of all 10 NICUs in the region. Infants <32 weeks gestation without major congenital anomalies admitted from 2007 to 2011 were included. Three authors reviewed all cases to agree upon the immediate cause of death.

Results

There were 345 (7.7%) deaths out of 4454 infants. The most common cause of death across all gestational groups was major IVH (cause-specific mortality rate [CMR] 22 per 1000 infants), followed by acute respiratory illnesses [ARI] (CMR 21 per 1000 infants) and sepsis (CMR 12 per 1000 infants). The most common cause of death was different in each gestational group (22–25 weeks [ARI], 26–28 weeks [IVH] and 29–31 weeks [perinatal asphyxia]). Pregnancy induced hypertension, antenatal steroids and chorioamnionitis were all associated with changes in CMRs. Deaths due to ARI or major IVH were more likely to occur at an earlier age (median [quartiles] 1.4 [0.3–4.4] and 3.6 [1.9–6.6] days respectively) in comparison to NEC and miscellaneous causes (25.2 [15.4–37.3] and 25.8 [3.2–68.9] days respectively).

Conclusions

Major IVH and ARI were the most common causes of hospital mortality in this extreme to very preterm population. Perinatal factors have a significant impact on cause-specific mortality. The varying timing of death provides insight into the prolonged vulnerability for diseases such as necrotising enterocolitis in our preterm population.

Neonatal Abstinence Syndrome and High School Performance

BACKGROUND AND OBJECTIVES

Little is known of the long-term, including school, outcomes of children diagnosed with Neonatal abstinence syndrome (NAS) (International Statistical Classification of Disease and Related Problems [10th Edition], Australian Modification, P96.1).

METHODS

Linked analysis of health and curriculum-based test data for all children born in the state of New South Wales (NSW), Australia, between 2000 and 2006. Children with NAS (n = 2234) were compared with a control group matched for gestation, socioeconomic status, and gender (n = 4330, control) and with other NSW children (n = 598 265, population) for results on the National Assessment Program: Literacy and Numeracy, in grades 3, 5, and 7.

RESULTS

Mean test scores (range 0-1000) for children with NAS were significantly lower in grade 3 (359 vs control: 410 vs population: 421). The deficit was progressive. By grade 7, children with NAS scored lower than other children in grade 5. The risk of not meeting minimum standards was independently associated with NAS (adjusted odds ratio [aOR], 2.5; 95% confidence interval [CI], 2.2-2.7), indigenous status (aOR, 2.2; 95% CI, 2.2-2.3), male gender (aOR, 1.3; 95% CI, 1.3-1.4), and low parental education (aOR, 1.5; 95% CI, 1.1-1.6), with all Ps < .001.

CONCLUSIONS

A neonatal diagnostic code of NAS is strongly associated with poor and deteriorating school performance. Parental education may decrease the risk of failure. Children with NAS and their families must be identified early and provided with support to minimize the consequences of poor educational outcomes.

Preterm infant outcomes in relation to the gestational age of onset and duration of prelabour rupture of membranes: a retrospective cohort study

OBJECTIVE

To determine the hospital outcomes of liveborn infants at 23-31 weeks following prelabour preterm rupture of membranes (PPROM).

METHOD

A regional retrospective cohort study of 4454 infants of 23-31 weeks' gestation admitted to a tertiary neonatal network between 2007 and 2011. Primary outcome was the composite chronic lung disease (CLD) or mortality at discharge.

RESULTS

225 (5%) neonates had a history of PPROM occurring prior to 24⁺⁰ weeks (Early-PPROM), 829 (19%) had a history of PPROM at or after 24⁺⁰ weeks' gestation (Late-PPROM) and 3400 (76%) had no history of PPROM (No-PPROM). In comparison to No-PPROM, Early-PPROM group had higher CLD/mortality in infants born at 23-27 weeks (OR 1.95; 95% CI 1.34 to 2.85) and 28-31 weeks (OR 4.98; 95% CI 2.99 to 8.28). Within Early-PPROM group, the latency of PPROM >14 days had lower CLD/mortality in comparison to latency ≤14 days (57.6% vs 77%, OR 0.40; 95% CI 0.21 to 0.76). Late-PPROM group had significantly lower CLD/mortality in comparison to No-PPROM group at 23-27 weeks (OR 0.50; 95% CI 0.37 to 0.69) and 28-31 weeks (OR 0.50; 95% CI 0.36 to 0.71). Within Late-PPROM group, latency >14 days was associated with an increased CLD/mortality in 28-31 weeks (14.1% vs 5.4%, OR 2.88; 95% CI 1.31 to 6.38).

CONCLUSIONS

Early-PPROM prior to 24 weeks' gestation had high incidence of CLD/mortality even after correcting for gestational age. Late-PPROM at or after 24 weeks had lower CLD/mortality compared with No-PPROM. Latency >14 days in Late-PPROM group at 28-31 week group increased the odds of CLD/mortality.

Population-based study shows that resuscitating apparently stillborn extremely preterm babies is associated with poor outcomes

AIM

This population-based study determined the delivery room management and outcomes of extremely preterm infants born with Apgar scores of 0.

METHODS

We linked birth, neonatal intensive care unit (NICU) and death records for babies who were born between 22 + 0 and 27 + 6 weeks of gestation with a one-minute Apgar score of 0, in New South Wales, Australia, between 1998 and 2011.

RESULTS

We classified 2173/2262 (96%) of infants with a one-minute Apgar score of 0 as stillborn. Resuscitation was provided for 48/89 (54%) live births and 40/2173 (2%) stillbirths. Cardiac massage was given to 44 infants, including three 22-week stillborn babies. Of the 13 live births admitted to an NICU, 11 survived to hospital discharge. Most (98%) of the 2212 deaths occurred on the first day of life. One baby who was classified as stillborn lived for 51 days. Resuscitation increased the mean (95% confidence interval) duration of survival from 1 (0-2) to 45 (0-104) hours (p < 0.001). No infant with a five-minute Apgar score of 0 survived.

CONCLUSION

Clinicians resuscitated extremely preterm infants without a detectable heartbeat, even at 22 weeks of gestation. No infant survived without resuscitation or if their heartbeat was not regained by five minutes.

Outcomes of infants with abdominal wall defects over 18years

BACKGROUND/PURPOSE

Infants with abdominal wall defects (AWD) are at risk of poor outcomes including prolonged hospitalization, infections and mortality. Our objective was to describe and compare the outcomes of infants admitted with gastroschisis and omphalocele over 18years.

METHODS

Population-based study of clinical data and outcomes of live-born infants with AWD admitted to all tertiary-level neonatal intensive care units in New South Wales and Australian Capital Territory from 1992 to 2009.

RESULT

There were 502 infants with AWD - 336 gastroschisis, 166 omphalocele. Infants with gastroschisis required a longer duration of total parenteral nutrition (19 vs 4days, p<0.05), longer hospitalization (28 vs 15days, p<0.05) and had a higher rate of systemic infection [23.5% vs 13.3%, OR 1.77 (1.15-2.74), p<0.05] compared to infants with omphalocele. Overall, omphalocele infants had higher mortality rate compared to gastroschisis infants [OR 2.77 (1.53, 5.04), p<0.05]. Gastroschisis mortality rates increased from epoch 1 to epoch 3 (4.2% to 8.8%).

CONCLUSION

Compared to infants with omphalocele, infants with gastroschisis required significantly longer hospitalization and parenteral nutrition with higher rates of infection. Infants with omphalocele had higher overall mortality rates. However, there has been an increase in the gastroschisis mortality rates but the cause for this is unclear.

A population study of respiratory rehospitalisation in very preterm infants in the first 3 years of life

AIM

Very premature infants consume healthcare resources following discharge from neonatal intensive care units (NICU). This study aimed to evaluate the burden of respiratory related rehospitalisation within the first 3 years post discharge in very premature infants in an Australian population.

METHODS

Rehospitalisation of a 4-year cohort of NICU survivors, born less than 32 weeks gestation, was derived from data linkage of three state-wide databases including NSW Neonatal Intensive Care Units' Data Collection, Admitted Patient Data Collection and the Death Registry. Rehospitalisation diagnoses were determined by ICD-10 AM codes.

RESULTS

Of the 2939 survivors, 525 (18%) had bronchopulmonary dysplasia (BPD) and 261 BPD infants (50%) were discharged on home oxygen. Almost two-third (1860, 63%) of the survivors are required rehospitalisation, respiratory causes, including 394 respiratory syncytial virus (RSV)-related, accounted for 2668 (48%) of the 5599 rehospitalisations. Significantly more home oxygen BPD survivors had respiratory (70%) and RSV-related (22%) rehospitalisations than the BPD infants not needing home oxygen (58% and 18%, respectively), and the survivors without BPD had the lowest rates (32% and 10%, P < 0.001). Most respiratory (61%) and RSV-related (74%) rehospitalisations occurred during the first 12 months post discharge. No RSV-related fatality occurred. Amongst the total 17 562 hospital days, respiratory and RSV-related admissions accounted for 10 905 (62%) and 3031 (17.2%) days. In multivariable logistic analyses, home oxygen and maternal indigenous status were independently associated with high (3 or more) respiratory and RSV rehospitalisation rates.

CONCLUSIONS

Respiratory rehospitalisations are common in very premature survivors. Home oxygen and indigenous status are significant risk factors for respiratory and RSV-related rehospitalisations.

Risk factors associated with RSV hospitalisation in the first 2 years of life, among different subgroups of children in NSW: a whole-of-population-based cohort study

BACKGROUND

Data on risk factors for respiratory syncytial virus (RSV)-associated hospitalisation in Australian children may be informative for preventive measures.

METHODS

A whole-of-population-based study was conducted to identify comparable risk factors for RSV hospitalisation in different subgroups of children aged <2 years in New South Wales. The cohort was divided into Indigenous children and high-risk and standard risk non-Indigenous children. Data on risk factors were obtained from the Perinatal Data Collection. RSV hospitalisations were ascertained from the Admitted Patient Data Collection. Adjusted HRs were calculated for each subgroup. Population-attributable risk associated with risk factors was estimated.

RESULTS

Four factors were associated with increased risk of RSV hospitalisation: maternal smoking during pregnancy, male sex, multiparity and birth during the first half of the RSV season. Increase in relative socioeconomic advantage was associated with decreased risk of hospitalisation. Among high and standard risk non-Indigenous children, the hazard was approximately double for children born to multiparous women compared to those born to primiparous women and among Indigenous children the hazard was approximately double among those born during the first half of the RSV season. Maternal smoking during pregnancy was associated with a 26-45% increased risk across subgroups and accounted for 17% (95% CI 9.3% to 24%) of RSV hospitalisations in Indigenous children, 5% (95% CI 2.5% to 8%) in high-risk and 6% (95% 5% to 7%) in standard risk non-Indigenous children.

DISCUSSION

Promoting avoidance of smoking during pregnancy may help in lowering the disease burden, with Indigenous children likely to benefit most.

Risk of neurodevelopmental impairment for outborn extremely preterm infants in an Australian regional network

OBJECTIVE

To compare neurodevelopmental outcomes at 2-3 years in extremely premature outborn and inborn infants.

DESIGN

Population-based retrospective cohort study.

SETTING

Geographically defined area of New South Wales (NSW) and the Australian Capital Territory (ACT) served by a network of 10 neonatal intensive care units (NICUs).

PATIENTS

All premature infants <29 weeks gestation born between 1998 and 2004 in the setting.

INTERVENTION

At 2-3 years, corrected age, 1473 children were assessed with either the Griffiths Mental Developmental Scales (GMDS) or the Bayley Scales of Infant Development (BSID-II).

MAIN OUTCOME MEASURE

Moderate/severe functional disability (FD) defined as: developmental delay (GMDS general quotient (GQ) or BSID-II mental developmental index (MDI)) > 2 standard deviations (SD) below the mean; cerebral palsy (CP) requiring aids; sensorineural or conductive deafness (requiring amplification); or bilateral blindness (visual acuity <6/60 in better eye).

RESULTS

At 2-3 years, moderate/severe functional disability does not appear to be significantly different between outborn and inborn infants (adjusted OR 0.782; 95% CI 0.424-1.443). However, there were a significant number of outborn infants lost to follow up (23.3% versus 42.9%).

CONCLUSION

In this cohort, at 2-3 years follow up neurodevelopmental outcome does not appear to be significantly different between outborn and inborn infants. These results should be interpreted with caution given the limitation of this study.

Epidemiological Evidence for a Decreasing Incidence of Neonatal Abstinence Syndrome, 2000-11

BACKGROUND

This study analyses the incidence of Neonatal Abstinence Syndrome (NAS) in a large geographically defined population in Australia.

METHOD

Database linkage analysis of all births between 2000 and 2011 in New South Wales (NSW), Australia. The diagnosis of NAS was derived from hospital coding P96.1, 'Neonatal withdrawal symptoms from maternal use of drugs of addiction'. Temporal trends were studied by comparing epoch 1 (2000-05) with epoch 2 (2006-11). The relationship with changes in maternal factors was further analysed.

RESULTS

The NAS was coded in 3842 of 1 022 263 live born infants (0.38%). NAS incidence peaked at 5.07 per 1000 live births in 2002, decreasing to 3.18 in 2011 and was negatively correlated with maternal age (r = -0.7). The rate of NAS in epoch 2 (3.4 per 1000 births, 95% CI 3.28, 3.58) was significantly lower than in epoch 1 (4.1 per 1000 births, 95% CI 3.96, 4.33). Epoch 2 mothers were significantly older (mean 29.8 years vs. 28.3 years), less likely to be multiparous (OR 0.7, 95% CI 0.6, 0.9) or smoke (OR 0.4, 95% CI 0.4, 0.5). They were more likely to engage in antenatal care earlier (mean first visit: 14.1 vs. 18.9 weeks). Most infants (~80%) were born at term (>37 weeks gestation).

CONCLUSION

The incidence of NAS as a discharge diagnosis has decreased in our population since 2002. Mothers are also older and engaging earlier in prenatal care. Whether these changes alter NAS presentation and diagnosis or whether pregnant women are using drugs that do not cause typical NAS (e.g. amphetamines) is uncertain and requires further study.

Sight-Threatening Retinopathy of Prematurity: Changing Trends in Treatment

PURPOSE

To study the incidence and treatment of severe retinopathy of prematurity (ROP) in infants younger than 30 weeks' gestational age (GA) in New South Wales and the Australian Capital Territory, Australia, from 2003 to 2008. These data were then compared to data from previously reported epochs (1986 to 1987, 1992 to 1997, and 1998 to 2002).

METHODS

Data were divided into two sub-epochs (2003 to 2005 and 2006 to 2008) to study trends and combined to compare over 22 years.

RESULTS

From 2003 to 2008, 2,550 of 3,004 (84.9%) infants survived, 200 (7.8%) were diagnosed as having severe ROP, and 119 (59.5%) required laser therapy. No significant difference in the incidence of severe ROP or treatment rate in infants younger than 27 and 30 weeks' GA from 2003 to 2005 and 2006 to 2008 occurred. Similarly, between 1986 and 2008 there was no difference in the incidence of severe ROP. However, the treatment rate significantly increased during this time.

CONCLUSIONS

The incidence of severe ROP has been stable since 1986. However, laser treatment significantly increased to include 8 infants with stage 2 ROP from 2003 to 2008.

Neurodevelopmental Outcomes of Premature Infants Treated for Patent Ductus Arteriosus: A Population-Based Cohort Study

OBJECTIVE

To compare neurodevelopmental outcomes of extremely preterm infants diagnosed with patent ductus arteriosus (PDA) who were treated medically or surgically and those who were not diagnosed with PDA or who did not undergo treatment for PDA.

STUDY DESIGN

This retrospective population-based cohort study used data from a geographically defined area in New South Wales and the Australian Capital Territory served by a network of 10 neonatal intensive care units. Patients included all preterm infants born at <29 completed weeks of gestation between 1998 and 2004. Moderate/severe functional disability at 2-3 years corrected age was defined as developmental delay, cerebral palsy requiring aids, sensorineural or conductive deafness (requiring bilateral hearing aids or cochlear implant), or bilateral blindness (best visual acuity of <6/60).

RESULTS

Follow-up information at age 2-3 years was available for 1473 infants (74.8%). Compared with infants not diagnosed with a PDA or who did not receive PDA treatment for PDA, those with medically treated PDA (aOR, 1.622; 95% CI, 1.199-2.196) and those with surgically treated PDA (aOR, 2.001; 95% CI, 1.126-3.556) were at significantly greater risk for adverse neurodevelopmental outcomes at age 2-3 years.

CONCLUSION

Our results demonstrate that treatment for PDA may be associated with a greater risk of adverse neurodevelopmental outcome at age 2-3 years. This was particularly so among infants born at <25 weeks gestation. These results may support permissive tolerance of PDAs; however, reasons for this association remain to be elucidated through carefully designed prospective trials.

Reasons for Rehospitalization in Children Who Had Neonatal Abstinence Syndrome

BACKGROUND AND OBJECTIVES

Neonatal abstinence syndrome (NAS) occurs after in utero exposure to opioids, but outcomes after the postnatal period are unclear. Our objectives were to characterize childhood hospitalization after NAS.

METHODS

Population-based linkage study of births, hospitalization, and death records of all children registered in New South Wales (NSW), Australia, between 2000 and 2011 to a maximum of 13 years. Infants with an International Statistical Classification of Disease and Related Problems, 10th Edition, Australian Modification, coding of NAS (P96.1, n = 3842) were compared with 1,018,421 live born infants without an NAS diagnosis.

RESULTS

Infants with NAS were more likely to be admitted into a nursery (odds ratio 15.6, 95% confidence interval: 14.5-16.8) and be hospitalized longer (10.0 vs 3.0 days). In childhood, they were more likely to be rehospitalized (1.6, 1.5-1.7), die during hospitalization (3.3, 2.1-5.1), and be hospitalized for assaults (15.2, 11.3-20.6), maltreatment (21.0, 14.3-30.9), poisoning (3.6, 2.6-4.8), and mental/behavioral (2.6, 2.1-3.2) and visual (2.9, 2.5-3.5) disorders. Mothers of infants with NAS were more likely to be Indigenous (6.4, 6.0-7.0), have no antenatal care (6.6, 5.9-7.4), and be socioeconomically deprived (1.6, 1.5-1.7). Regression analyses demonstrated that NAS was the most important predictor of admissions for maltreatment (odds ratio 4.5, 95% confidence interval: 3.4-6.1) and mental and behavioral disorders (2.3, 1.9-2.9), even after accounting for prematurity, maternal age, and Indigenous status.

CONCLUSIONS

Children with NAS are more likely to be rehospitalized during childhood for maltreatment, trauma, and mental and behavioral disorders even after accounting for prematurity. This continues to adolescence and emphasizes the critical need for continued support of this vulnerable group after resolution of NAS.

Neurodevelopmental outcome of extremely preterm infants born to rural and urban residents' mothers in Australia

BACKGROUND

Rural and remote residents in Australia have long experienced unfavourable health outcomes compared to their urban counterparts.

AIMS

To study neurodevelopmental outcome at 2-3 years of age, corrected for prematurity of extremely preterm infants admitted to a regional neonatal Australian network from rural and urban regions (based on usual location of maternal residence).

METHODS

A multicenter population-based cohort study in which surviving urban and rural infants <29 weeks of gestation born between 1998 and 2004 underwent neurodevelopmental assessment at 2-3 years of age, corrected for prematurity by a developmental assessment team. Moderate/severe functional disability was defined as developmental delay (GQ or MDI>2 SD below the mean), cerebral palsy (aided for walking), sensorineural or conductive deafness (requiring amplification), and bilateral blindness (visual acuity <6/60 in the better eye).

RESULTS

Of the 1970 infants alive at 2-3 years of age, 268 (63.8%) rural and 1205 (77.7%) urban infants were evaluated. Infants lost to follow-up were of slightly higher gestational age and birth weight. Both rural and urban assessed groups were comparable in gestation and birth weight percentile. In comparison to their urban counterparts, the rural group had more outborn infants (19.8% vs. 4.6%, p<0.001). They, however, did not have an increased risk of moderate/severe functional disability (OR 0.77, 95% CI 0.52-1.23, p=0.176). This finding was not significantly altered by limiting the analysis to different gestational ages.

CONCLUSION

Extremely premature surviving young children from rural areas of residence do not seem to have an increased risk for moderate/severe functional disability.

Preterm infant outcomes in New South Wales and the Australian Capital Territory

AIM

This study aimed to provide updated information on gestation-specific hospital outcomes of extreme to very preterm infants admitted to neonatal intensive care units.

METHODS

A population-based retrospective cohort study of infants born between 23(+0) and 31(+6) weeks gestation and admitted to a network of neonatal intensive care units between 2007 and 2011 in a well-defined geographic area of New South Wales and the Australian Capital Territory. Main outcome measures were survival and major morbidities prior to hospital discharge.

RESULTS

Of 4454 infants included, hospital survival rates based on gestational age alone were 27%, 59%, 76%, 85%, 91% and over 95% at 23, 24, 25, 26, 27 and 28-31 weeks, respectively. Survival rates for each week up to 29 weeks gestation differed by at least 5% when perinatal risk factors including birthweight percentile, exposure to antenatal steroids, birth outside a tertiary hospital and gender were included in the survival estimation. All the major outcome figures were then simplified and displayed in a simple, easy-to-understand preterm outcome table for counselling purposes.

CONCLUSION

We report the latest hospital outcomes of extreme to very preterm infants in New South Wales and the Australian Capital Territory. Survival rates based on gestational age alone may not provide the true estimate as the survival for these infants can vary based on the presence or absence of other relevant perinatal factors.

Comparing CRIB-II and SNAPPE-II as mortality predictors for very preterm infants

AIMS

This article compares the severity of illness scoring systems clinical risk index for babies (CRIB)-II and score for neonatal acute physiology with perinatal extension (SNAPPE)-II for discriminatory ability and goodness of fit in the same cohort of babies of less than 32 weeks gestation and aims to provide validation in the Australian population.

METHODS

CRIB-II and SNAPPE-II scores were collected on the same cohort of preterm infants born within a 2-year period, 2003 and 2004. The discriminatory ability of each score was assessed by the area under the receiver operator characteristic curve, and goodness of fit was assessed by the Hosmer-Lemeshow (HL) test. The outcome measure was in-hospital mortality. A multivariate logistic regression model was tested for perinatal variables that might add to the risk of in-hospital mortality.

RESULTS

Data for both scores were available for 1607 infants. Both scores had good discriminatory ability (CRIB-II area under the curve 0.913, standard error (SE) 0.014; SNAPPE-II area under the curve 0.907, SE 0.012) and adequate goodness of fit (HL χ²  = 11.384, 8 degrees of freedom, P = 0.183 for CRIB-II; HL χ²  = 4.319, 7 degrees of freedom, P = 0.742 for SNAPPE-II). The multivariate model did not reveal other significant variables.

CONCLUSIONS

Both severity of illness scores are ascertained during the first 12 h of life and perform similarly. Both can facilitate risk-adjusted comparisons of mortality and quality of care after the first post-natal 12 h. CRIB-II scores have the advantage of being simpler to collect and calculate.

Neurodevelopmental outcomes of preterm singletons, twins and higher-order gestations: a population-based cohort study

OBJECTIVE

To study the neurodevelopmental outcomes of multiple (twins, triplets, quads) compared with singleton extremely preterm infants <29 weeks gestation.

DESIGN

Population-based retrospective cohort study.

SETTING

A network of 10 neonatal intensive care units in a geographically defined area of New South Wales and the Australian Capital territory.

PATIENTS

1473 infants <29 weeks gestation born between 1 January 1998 and 31 December 2004.

INTERVENTION

At 2-3 years of corrected age, a neurodevelopmental assessment was conducted using either the Griffiths Mental Developmental Scales or the Bayley Scales of Infant Development II.

MAIN OUTCOME MEASURE

Moderate-severe functional disability was defined as developmental delay (Griffiths Mental Developmental Scales General Quotient or Bayley Scales of Infant Development-II Mental Development Index >2 SDs below the mean), moderate cerebral palsy (unable to walk without aids), sensorineural or conductive deafness (requiring amplification) or bilateral blindness (visual acuity <6/60 in the better eye).

RESULTS

Of the 1081 singletons and 392 multiples followed-up, singletons demonstrated higher rates of systemic infections, steroid treatment for chronic lung disease and birth weight <10th percentile. Moderate-severe functional disability did not differ significantly between singletons and multiples (15.8% vs 17.6%, OR 1.14; 95% CI 0.84 to 1.54; p=0.464). Further subgroup analysis of twins, higher-order gestations, 1st-born multiples, 2nd or higher-born multiples, same and unlike gender multiples, did not demonstrate statistically higher rates of functional disability compared with singletons.

CONCLUSIONS

Premature infants from multiple gestation pregnancies appear to have comparable neurodevelopmental outcomes to singletons.

Population study of neurodevelopmental outcomes of extremely premature infants admitted after office hours

AIM

The aim of the study was to compare neurodevelopmental outcomes of extremely preterm infants admitted during (OH) and after (AH) office hours.

METHODS

A retrospective review of the New South Wales and Australian Capital Territory Neonatal Intensive Care Units' (NICUs) Data Collection of all infants <29 weeks gestation admitted to New South Wales and Australian Capital Territory NICUs between January 1998 and December 2004 was conducted. The primary outcome was moderate/severe functional disability (FD) at 2-3 years follow-up defined as developmental delay (Griffiths Mental Developmental Scales general quotient or Bayley Scales of Infant Development-II mental developmental index >2 standard deviations below the mean), cerebral palsy (unable to walk without aids), deafness (requiring bilateral hearing aids) or blindness (visual acuity <6/60 in the better eye).

RESULTS

Mortality and age at follow-up were comparable between the AH and OH groups. Developmental outcome was evaluated in 972 (74.9%) infants admitted during AH and 501 (74.6%) admitted during OH. FD was not significantly different between the AH and OH groups (17.1% vs. 14.8%, adjusted odds ratio 1.131, 95% confidence interval 1.131 (0.839-1.523), P = 0.420). There were no significant differences between AH and OH infants with cerebral palsy (9.6% vs. 7.6%), developmental delay (5.4% vs. 5.0%) or any other component of FD.

CONCLUSION

There is little circadian variation in mortality and adverse neurodevelopmental outcomes in an NICU network with the current model of after hours staffing and support, and sharing of NICU workload within a network.

Intraventricular hemorrhage and neurodevelopmental outcomes in extreme preterm infants

OBJECTIVE

Not many large studies have reported the true impact of lower-grade intraventricular hemorrhages in preterm infants. We studied the neurodevelopmental outcomes of extremely preterm infants in relation to the severity of intraventricular hemorrhage.

METHODS

A regional cohort study of infants born at 23 to 28 weeks' gestation and admitted to a NICU between 1998 and 2004. Primary outcome measure was moderate to severe neurosensory impairment at 2 to 3 years' corrected age defined as developmental delay (developmental quotient >2 SD below the mean), cerebral palsy, bilateral deafness, or bilateral blindness.

RESULTS

Of the 1472 survivors assessed, infants with grade III-IV intraventricular hemorrhage (IVH; n = 93) had higher rates of developmental delay (17.5%), cerebral palsy (30%), deafness (8.6%), and blindness (2.2%). Grade I-II IVH infants (n = 336) also had increased rates of neurosensory impairment (22% vs 12.1%), developmental delay (7.8% vs 3.4%), cerebral palsy (10.4% vs 6.5%), and deafness (6.0% vs 2.3%) compared with the no IVH group (n = 1043). After exclusion of 40 infants with late ultrasound findings (periventricular leukomalacia, porencephaly, ventricular enlargement), isolated grade I-II IVH (n = 296) had increased rates of moderate-severe neurosensory impairment (18.6% vs 12.1%). Isolated grade I-II IVH was also independently associated with a higher risk of neurosensory impairment (adjusted odds ratio 1.73, 95% confidence interval 1.22-2.46).

CONCLUSIONS

Grade I-II IVH, even with no documented white matter injury or other late ultrasound abnormalities, is associated with adverse neurodevelopmental outcomes in extremely preterm infants.

The association between maternal country of birth and neonatal intensive care unit outcomes

BACKGROUND

Immigration is increasingly common worldwide and its impact on neonatal intensive care unit outcomes is uncertain.

AIMS

To determine the outcomes of children of immigrant mothers admitted to NICUs in New South Wales (NSW), Australia, between 2000 and 2006.

STUDY DESIGN

Record linkage study of routinely collected state-based health databases.

SUBJECTS

Infants of Australian-born (9813, 81.9%) and overseas born mothers (2166, 18.1%).

OUTCOME MEASURES

NICU and childhood outcomes to a maximum 5 years of age.

RESULTS

Immigrant mothers came from 122 countries, 897 (44%) from high income regions. Australian born mothers were more likely to be teenaged (Odds Ratio, 95% confidence interval: 3.07, 2.21-4.26), use drugs (3.55, 2.49-5.06) and suffer an antepartum hemorrhage (1.29, 1.14-1.48). They were less likely to have gestational diabetes (0.45, 0.38-0.54), fetal distress (0.75, 0.66-0.85) and intrauterine growth restriction (0.80, 0.67-0.93). Their infants were more likely to be admitted to the NICU for prematurity but less likely to have low 5 min Apgar scores (0.81, 0.69-0.93) or a congenital abnormality (0.79, 0.70-0.90). Infants of Middle-Eastern mothers had the lowest hospital survival rate (88.5%). Children of immigrant Asian mothers were least likely to be rehospitalized after NICU discharge (1.66, 1.27-2.17).

CONCLUSIONS

NICU outcomes are affected by maternal country of birth even within the same ethnic group. Further study regarding the impact of paternal race and immigration status and duration of residency will provide data for the changing cultural environment of global perinatal care.

Actuarial day-by-day survival rates of preterm infants admitted to neonatal intensive care in New South Wales and the Australian Capital Territory

OBJECTIVE

To characterise the actuarial day-by-day survival of premature infants in a geographically defined population.

SETTING

10 Neonatal Intensive Care Units (NICUs) in New South Wales (NSW) and Australian Capital Territory (ACT), Australia.

DESIGN

Retrospective analysis of prospectively collected data as part of NICUs' data collection in NSW and ACT.

SUBJECTS

Premature infants born at 22(+0) to 31(+6) weeks' gestation between January 1997 and December 2006 and admitted to one of the 10 NICUs in NSW and ACT.

OUTCOME

Actuarial day-by-day survival to discharge from NICU.

RESULTS

Survival to discharge after initiation of neonatal intensive care ranges from 30.0% at 23 weeks' gestation to 98.8% at 31 weeks. Actuarial day-by-day survival increased across all gestations. This improvement was most notable among the babies who were born <26 weeks gestation.

CONCLUSION

Preterm infants who survive the first few postnatal days have considerable chances of long-term survival. It is important to revise the information stored regarding chances of survival so it covers chances at regular intervals, especially after the first few days of life.

Neurodevelopmental outcomes of extremely premature infants conceived after assisted conception: a population based cohort study

OBJECTIVE

To compare neurodevelopmental outcomes of extremely preterm infants conceived after assisted conception (AC) compared with infants conceived spontaneously (non-AC).

DESIGN

Population-based retrospective cohort study.

SETTING

Geographically defined area in New South Wales and the Australian Capital Territory, Australia served by a network of 10 neonatal intensive care units.

PATIENTS

Infants <29 weeks' gestation born between 1998 and 2004.

INTERVENTION

At 2-3 years corrected age, 1473 children were assessed with either the Griffiths Mental Developmental Scales or the Bayley Scales of Infant Development.

MAIN OUTCOME MEASURE

Moderate/severe functional disability defined as developmental delay (Griffiths General Quotient or Bayley Mental Developmental Index >2 SD below the mean), cerebral palsy (unable to walk without aids), deafness (bilateral hearing aids or cochlear implant) or blindness (visual acuity <6/60 in the better eye).

RESULTS

Mortality and age at follow-up were comparable between the AC and non-AC groups. Developmental outcome was evaluated in 217 (86.5%) AC and 1256 (71.7%) non-AC infants. Using multivariate adjusted analysis, infants born after in-vitro fertilisation at 22-26 weeks' gestation (adjusted OR 1.79, 95% CI 1.05 to 3.05, p=0.03) but not at 27-28 weeks' gestation (adjusted OR 0.81, 95% CI 0.37 to 1.77; p=0.59) had higher rate of functional disability than those born after spontaneous conception.

CONCLUSIONS

AC is associated with adverse neurodevelopmental outcome among high risk infants born at 22-26 weeks' gestation. This finding warrants additional exploration.

Causes of death in infants admitted to Australian neonatal intensive care units between 1995 and 2006

AIM

To compare causes and rates of mortality among infants admitted to 10 Australian neonatal intensive care units (NICUs) between 1995 and 2006.

METHODS

De-identified perinatal data from the Neonatal Intensive Care Units' (NICUS) Data Collection for 24 131 infants were examined for causes and rates of death. The study period was divided into two epochs: I (1995-2000, n = 11 185 infants) and II (2001-2006, n = 12 946 infants).

RESULTS

A total of 2224 (9.2%) infants died in hospital. Mortality decreased from 10.3% (1152/11 185) in epoch I to 8.3% (1072/12 946) in epoch II (p < 0.001) due to improved survival in term infants. Extreme prematurity also decreased as a primary cause of death (118 (10.2%) vs 76 (7.1%), p = 0.008). No infant >42-week gestation was admitted in epoch II. Congenital abnormalities were the most common cause of death (>20%) in both epochs, mostly in term rather than preterm infants (40.7% vs 13.9%, p < 0.001). Age of death was unchanged between the two epochs (median 4, 1st, 3rd quartiles: 1,16 days).

CONCLUSION

Mortality rates have continued to decrease but improvement is predominantly due to improved survival of term infants and prevention of postdate deliveries. Congenital abnormalities continue to be the most common cause of death.

Can the early condition at admission of a high-risk infant aid in the prediction of mortality and poor neurodevelopmental outcome? A population study in Australia

AIM

The aim of this article was to evaluate the Revised Clinical Risk Index for Babies' (CRIB-II) severity of illness score as a predictor of moderate to severe functional disability (FD) in very premature infants.

METHODS

Population study of infants born <29 weeks' gestation cared for in all Neonatal Intensive Care Unit in New South Wales and the Australian Capital Territory between 1998 and 2003. FD at 2-3 years corrected age was defined as developmental delay (quotient < 2 standard deviation), non-ambulatory cerebral palsy (needing aids to walk), blindness (acuity <6/60 in better eye) or deafness (hearing aids). Sensitivity and specificity of CRIB-II scores to predict FD were performed by receiver operating characteristic curve analysis.

RESULTS

Of study population of 2210, 480 (21.7%) died before hospital discharge. Among 1328 infants assessed, 217 (16.3%) had FD, 109 (8.2%) developmental delay, 75 (5.6%) cerebral palsy and 54 (4.1%) blindness or deafness. CRIB-II performed significantly better than gestation or birthweight (BW) alone in predicting mortality (area under the curve (AUC) ± standard error 0.83 ± 0.01, vs. 0.78 ± 0.01 and 0.76 ± 0.01, respectively). CRIB-II scores were significantly higher in FD than non-FD children (11.9 ± 2.9 vs. 10.1 ± 2.6), but the AUC for CRIB-II (0.68 ± 0.02) did not significantly differ from that of gestation (0.65 ± 0.02) and BW (0.65 ± 0.02).

CONCLUSION

CRIB-II improved prediction of mortality but did not perform better than gestational age or BW in predicting FD. We would caution clinicians against using the infant's condition at admission to predict long-term outcome.

The associations between ethnicity and outcomes of infants in neonatal intensive care units

OBJECTIVE

To determine the associations between maternal ethnicity and outcomes of infants born between 22 and 31 weeks' gestation and admitted to neonatal intensive care units in New South Wales and the Australian Capital Territory, Australia, between 1995 and 2006.

DESIGN AND PATIENTS

De-identified perinatal and neonatal outcome data for 10 267 infants were examined. There were 8629 (84.0%) Caucasian, 922 (9.0%) Asian, 439 (4.3%) indigenous, 127 (1.2%) Polynesian and Maori (PAM) and 150 (1.5%) infants of other maternal ethnicities (excluded from study). Caucasians were the referent for all comparisons.

RESULTS

Infants of indigenous mothers were less likely to receive antenatal steroids and three times as likely to be born in non-tertiary hospitals (OR 3.28, 95% CI 2.59 to 4.16, p<0.001). PAM infants were more likely to have Apgar scores <7 at 5 min of age (1.76, 95% CI 1.16 to 2.67, p<0.01). Asian infants had lower birth weight (mean±SD 44.7±27.9, p<0.001) and head circumference percentiles (47.8±29.0, p<0.001), were more likely to be small for gestational age (1.53, 95% CI 1.25 to 1.88, p<0.001), less likely to have hyaline membrane disease (0.78, 95% CI 0.68 to 0.90, p<0.001) but had a higher risk of severe retinopathy of prematurity (1.52, 95% CI 1.11 to 2.07, p<0.01). Ethnicity did not influence infant mortality.

CONCLUSIONS

Neonatal growth characteristics and morbidity but not mortality are influenced by maternal ethnicity. Of concern is the risk of low Apgar scores in PAM infants and non-tertiary births of indigenous infants. Review of perinatal care for certain vulnerable ethnic populations is recommended due to the rapidly changing ethnic compositions of many countries around the world.

Perinatal characteristics and outcome of preterm singleton, twin and triplet infants in NSW and the ACT, Australia (1994-2005)

OBJECTIVE

To compare the perinatal characteristics, neonatal morbidity and mortality of preterm singletons, twins and triplets born at 22-31 weeks' gestation and admitted to neonatal intensive care units (NICU) in New South Wales and Australian Capital Territory between 1994 and 2005.

METHODS

Perinatal characteristics and neonatal outcome data were obtained from the regional NICUS data collection to test for a priori hypothesis. The 10 068 very premature infants studied included 7304 (72.5%) singletons, 2444 (24.2%) twins and 320 (3.2%) triplets.

RESULTS

Assisted conception was associated with a higher maternal age and increased twins and triplets admissions into NICU than spontaneous conceptions (twins OR 6.9, 95% CI 6.1 to 8.0; and triplets OR 35.6, 95% CI 27.6 to 45.8). Major neonatal morbidities were similar between the three groups of singletons, twins or triplets. While twins of 22-27 weeks' gestation (adjusted OR 1.39, 95% CI 1.12 to 1.72) had higher mortality compared with singletons, mortality only diverged below 24 weeks' gestation. Mortality was predicted by decreasing gestational age, male gender and lack of antenatal steroids, whereas assisted conception was protective against mortality (adjusted OR 0.69, 95% CI 0.57 to 0.86).

CONCLUSIONS

Assisted conception contributed to higher very premature NICU admissions of twins and triplets. Preterm twins at the very extreme of viability had higher mortality compared with singletons. The protective effect of assisted conception against mortality requires further research.

Geographically based investigation of the influence of very-preterm births on routine mortality statistics from the UK and Australia

BACKGROUND

Comparisons of national perinatal and neonatal mortality often neglect the underlying causes.

OBJECTIVE

To assess effects of very-preterm births in the UK and Australia.

SETTING

Two geographically defined populations: the former Trent Health Region of the UK and New South Wales (NSW)/the Australian Capital Territory (ACT), Australia.

METHOD

All births 22(+0) to 31(+6) weeks in 2000, 2001 and 2002 were identified by established surveys of perinatal care. Rates of birth and death were compared.

RESULTS

The population of NSW/ACT was 35% higher and there were 66% more births than in Trent (273 495 vs 164 824). The proportion of liveborn infants between 22 and 31 weeks gestation was about 25% higher in Trent (NSW/ACT 2945, rate per 1000 live births 10.82 (95% CI 10.43 to 11.22); Trent 2208, rate per 1000 live births 13.47 (95% CI 12.92 to 14.05)). The proportion of these infants admitted to a neonatal unit was also higher in Trent (91.2% vs 94.4%; OR 1.63 (95% CI 1.30 to 2.05)). Unadjusted mortality in infants admitted to a neonatal unit was similar: NSW/ACT 332/2686 (12.4%); Trent 284/2085 (13.6%); unadjusted OR 1.12 (95% CI 0.94 to 1.33; p = 0.21).

CONCLUSIONS

The higher rates of very premature birth and more ready admission to neonatal intensive care for infants in the UK may help to explain why perinatal and neonatal mortality are higher there than in Australia. Efforts to understand why the rate of premature birth in the UK is so high should be a national priority.

Using hospital discharge data for determining neonatal morbidity and mortality: a validation study

BACKGROUND

Despite widespread use of neonatal hospital discharge data, there are few published reports on the accuracy of population health data with neonatal diagnostic or procedure codes. The aim of this study was to assess the accuracy of using routinely collected hospital discharge data in identifying neonatal morbidity during the birth admission compared with data from a statewide audit of selected neonatal intensive care (NICU) admissions.

METHODS

Validation study of population-based linked hospital discharge/birth data against neonatal intensive care audit data from New South Wales, Australia for 2,432 babies admitted to NICUs, 1994-1996. Sensitivity, specificity and positive predictive values (PPV) with exact binomial confidence intervals were calculated for 12 diagnoses and 6 procedures.

RESULTS

Sensitivities ranged from 37.0% for drainage of an air leak to 97.7% for very low birthweight, specificities all exceeded 85% and PPVs ranged from 70.9% to 100%. In-hospital mortality, low birthweight (< or =1500 g), retinopathy of prematurity, respiratory distress syndrome, meconium aspiration, pneumonia, pulmonary hypertension, selected major anomalies, any mechanical ventilation (including CPAP), major surgery and surgery for patent ductus arteriosus or necrotizing enterocolitis were accurately identified with PPVs over 92%. Transient tachypnea of the newborn and drainage of an air leak had the lowest PPVs, 70.9% and 83.6% respectively.

CONCLUSION

Although under-ascertained, routinely collected hospital discharge data had high PPVs for most validated items and would be suitable for risk factor analyses of neonatal morbidity. Procedures tended to be more accurately recorded than diagnoses.

Delivery in the ‘grey zone’: Collaborative approach to extremely preterm birth

During the recent New South Wales and Australian Capital Territory consensus workshop on Perinatal Care at the limits of viability, recommendations were made in the areas of education, counselling and management. Critically, there was a consensus that between 23 weeks and zero days and 25 weeks and six days of gestation, it was reasonable to offer the option of non-initiation of resuscitation and intensive care. Within this, obligation to treat increases as the gestation advances. Implications of the statement for obstetricians are discussed in this article.