ARTICLE |
a Department of Newborn Care, Royal Hospital for Women, Randwick, Australia
b School of Women's and Children's Health, University of New South Wales, Sydney, Australia
c New South Wales Newborn and Pediatric Emergency Transport Service, Westmead, Australia
d Neonatal Intensive Care Units' Data Collection
e New South Wales Pregnancy and Newborn Services Network, New South Wales Center for Perinatal Health Services Research, University of Sydney, Sydney, Australia
| ABSTRACT |
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METHODS. The intervention included additional, network-coordinated, perinatal telephone advice to optimize in utero transfers and centralization of the neonatal retrieval system, with preferential admission of retrieved infants (outborn infants) to perinatal centers instead of freestanding pediatric hospitals, from the middle of 1995. Population birth and NICU admission cohorts of infants of 23 to 28 weeks of gestation were studied. Outcomes of epoch 1 (1992 to the middle of 1995; 1778 births and 1100 NICU admissions) were compared with those of epoch 2 (1997–2002; 3099 births and 2100 NICU admissions), after an 18-month washout period.
RESULTS. There were 25% fewer nontertiary hospital live births (19.7% vs 14.9%) and more prenatal steroid use. Despite an 11.4% average annual increase in NICU admissions between the 2 epochs, fewer infants were outborn (12.0% vs 9.3%) and outborn mortality rates decreased significantly (39.4% vs 25.1%), particularly for those between 27 and 28 weeks of gestation. The overall improvement was equivalent to 1 extra survivor per 16 New South Wales births. There were also significantly fewer serious outcome morbidities in outborn infants during epoch 2, over the improvements in inborn infants.
CONCLUSIONS. Statewide coordinated strategies in reducing nontertiary hospital births and optimizing transport of outborn infants to perinatal centers have improved considerably the outcomes of extremely premature infants. These findings have vital implications for health outcomes and resource planning.
Key Words: premature infant outcome perinatal services neonatal retrieval perinatal mortality
Abbreviations: OR—odds ratio CI—confidence interval NSW—New South Wales PSN—Pregnancy and Newborn Services Network PAL—Perinatal Advice Line ACT—Australian Capital Territory NICUS—Neonatal Intensive Care Units' NETS—Newborn and Pediatric Emergency Transport Service
Transferring women at risk of very preterm birth to perinatal centers for delivery decreases the neonatal mortality rate considerably.1–4 Infants born outside such centers (outborn infants) are at increased risk of developing many major neonatal complications1–5 and long-term neurodevelopmental disabilities,5–7 possibly because of suboptimal resuscitation at birth or poor access to specialist support.5,8 After birth, outborn infants also may be compromised by the speed and efficiency with which eventual transfer to an appropriate tertiary center is accomplished. In addition, the type of tertiary facility to which the infants are transferred may influence outcomes. For example, Shah et al9 demonstrated that Canadian, outborn, premature (<32 weeks) infants admitted to perinatal centers had a lower risk of death, compared with those admitted to freestanding pediatric hospitals (adjusted odds ratio [OR]: 2.25; 95% confidence interval [CI]: 1.20–4.20); staff and management policies in such facilities may not be equipped or accustomed to the needs of premature infants, because of low patient volumes.
The state of New South Wales (NSW) in Australia is geographically vast. With a total land area of 809443 km2, NSW is
25% larger than Texas (696241 km2). It has a population of only 6.7 million, however, with >4 million concentrated in the coastal and metropolitan areas of Sydney, and 24% of births occur in remote facilities or rural centers.10 The annual birth rate in NSW is
87000 births per year, with most infants (69000 births per year; 79%) being delivered in nontertiary hospitals.11
The NSW Pregnancy and Newborn Services Network (PSN) was established in 1991 to oversee the planning, coordination, and regionalization of perinatal services. There are 6 perinatal centers and 2 pediatric hospitals in Sydney and 1 perinatal center in Newcastle (150 km north of Sydney). An electronic NICU bed-state bulletin board was introduced in 1992 to facilitate transfers and NICU data collection for clinical audits. Before 1995, outborn NSW infants were transferred preferentially to 1 of 2 freestanding pediatric hospitals in Sydney. Each of the 2 pediatric hospitals and the perinatal center in Newcastle at that time maintained an individually staffed and locally coordinated transport service.
In 1995, PSN coordinated the development of 3 major changes within NSW, the aims of which were to reduce the number of outborn infants and to reduce the incidence of death and morbidities associated commonly with these high-risk deliveries. Firstly, the transport services from the 2 freestanding pediatric hospitals in Sydney were combined and centralized to form a single, independent, statewide service, the NSW Newborn and Pediatric Emergency Transport Service (NETS). This service covered the entire state of NSW. The scope and infrastructure of NETS have been described elsewhere.12
Secondly, because it was though that perinatal centers were better equipped and more experienced in the care of tiny infants, infants at <32 weeks of gestation were transported preferentially to perinatal centers. Two of the perinatal centers, as well as the pediatric hospitals, have the capacity to offer pediatric surgery. The NICU directors agreed to this concept in 1994, during the NETS amalgamation planning. Some of these destination changes, although they become evident in 1994, became more widely recognized in 1995, as part of the NETS destination advice guidelines that were disseminated to referring pediatricians.
Finally, the Perinatal Advice Line (PAL) was established. This is a statewide, fetal/maternal specialist, telephone service that provides assistance to community hospital obstetricians; it aims to encourage, to coordinate, and to optimize the clinical conditions of in utero transfers to tertiary centers. The PAL is activated whenever there are uncertainties regarding the management of high-risk pregnancies or the safety of potential transfers.
This study was designed to assess the effects of these changes on the outcomes of outborn infants in the state of NSW. The study period was divided into 2 epochs, namely, January 1992 to June 1995, before implementation of the 3 changes described above (epoch 1, or the precentralization epoch), and January 1997 to December 2002, after implementation of those changes (epoch 2) and an 18-month washout period. We hypothesized that the outcomes of outborn, high-risk, extremely premature infants, especially the mortality and morbidity rates of extremely preterm (23–28 weeks of gestation) infants, would be improved after implementation of those strategic changes.
| METHODS |
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The NSW Midwives Data Collection provides baseline population data for all births between 23 and 28 weeks of gestation in NSW hospitals. Births occurring in hospitals in the Australian Capital Territory (ACT) (
4500 per year) are not part of the NSW Midwives Data Collection. The ACT lies within the boundary of NSW, and the NICU in the Canberra Hospital of the ACT is a member of the regional NICU network data collection. However, to provide consistency for analysis within the study hypothesis, only hospital births and outcomes from NICUs in NSW were analyzed; there were very few cross-boundary outborn admissions between ACT and NSW (10 infants in 7 years after the Canberra Hospital joined the NICUS Data Collection in 1995).
Operationally, after 1992, NICUS data were collected prospectively and collated within each NICU by a designated data manager, usually with a professional background in neonatal nursing. The data manager uses standardized published definitions13 to compile information in a central database. The accuracy of NICUS Data Collection data was validated in 1999.13
This study was restricted to infants born between 23 weeks 0 days and 28 weeks 6 days of gestation. Outborn infants were defined as those who were not born in any of the 7 perinatal centers in NSW. Infants who died before or during retrieval were not included for analysis, because such data were not collected during the first epoch.
Statistical Analyses
Analyses were performed with SPSS 11.5.0 (SPSS, Chicago, IL). The
2 test and t test were used where appropriate. Multivariate analysis was performed by means of multiple logistic regression analyses with stepwise elimination based on likelihood ratio,14,15 with entry and removal criteria of P < .05 and P > .10, respectively. We used the difference-in-differences analysis technique16 to differentiate the effects of the strategic changes on the outborn mortality rate and other outcome variables from the overall downward trend in neonatal mortality rates over time. The statistical significance of the differences was calculated by using the SEs of the differences. The level of statistical significance for all analyses was set at P < .05, using 2-tailed comparisons. The significance level was not changed when multiple comparisons were performed.17
| RESULTS |
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508 births per year) during epoch 1 and 3099 similar births (
517 births per year, a 1.7% increase) during epoch 2 (Table 1). The stillbirth rate was marginally (2.1%) lower. There was a significant reduction in the number of extremely premature births occurring in nontertiary hospitals from epoch 1 to epoch 2 (30.1% and 24.6%, respectively; P < .001), which was mostly attributable to a 25% decrease in the proportion of nontertiary hospital live births (19.7% vs 14.9% of all live births; P < .001), of which a disproportionate 83% were of 23 to 25 weeks of gestation (Table 1).
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Difference-in-differences analyses showed significant improvement in most neonatal morbidity rates for outborn infants during epoch 2, above that of inborn infants (Table 3). However, there were more chronic lung diseases in epoch 2, although less postnatal steroid treatment and home oxygen therapy.
| DISCUSSION |
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Our findings are particularly important because the rate of extremely premature births, both locally11,22 and nationally,23 will most likely continue to increase in the near future, because of widespread increases in maternal age and in the use of assisted conception. This study showed a striking 25% reduction in the number of nontertiary hospital live births, a concurrent and significant reduction in the outborn mortality rate (from 39.4% to 25.1%), and a substantial decrease in the overall NICU mortality rate (from 27.1% to 23.7%). This result, when taken together with the 2.0% reduction in the number of stillbirths, equates to an increase in the number of NICU survivors per total births of 6.6% in epoch 2, or an equivalent of 1 extra survivor for every 16 extremely premature births (all stillbirths and live births combined).
The outborn infants who were admitted eventually to NICUs might have been a biased and favored group, because they might have been more robust than infants who were not selected by local practitioners for transfer.24 In the current study, only approximately one half of nontertiary hospital live births were offered NICU care in both epochs, compared with almost all of the live inborn infants. Imminent labor or a pessimistic regional obstetric attitude, as shown in our national survey,25 might have delayed or prevented in utero or ex utero transfers, and nontransferred infants would most certainly have died, because NSW has no facilities to care for extremely preterm infants outside the 9 perinatal urban units. Unfortunately, data on nontertiary neonatal deaths are not available; therefore, this confounding factor cannot be assessed currently.
However, these issues do not detract from the fact that outborn mortality rates, particularly for infants of 27 to 28 weeks, improved dramatically during the 2 study epochs. The formation of a centralized statewide neonatal transport service (NETS), with its multiple, rapid-response, transport teams, most likely played a major role. McNamara et al26 showed that the presence of a skilled transport team at high-risk deliveries improved the quality of neonatal resuscitation significantly. This finding was confirmed by Hood et al,27 who showed that outborn infants who were not transferred to a NICU by a neonatal transport team had a 60% greater mortality rate. Of note, more outborn mothers received prenatal steroid therapy in epoch 2. This practice might also have been a surrogate marker of improved peripheral hospital access to expert advice through the PAL network.
Furthermore, the transport policy that delegates preference for the transfer of premature infants to perinatal centers likely would have improved outcomes, because perinatal centers are considerably more accustomed to managing prematurity-associated problems (because of greater patient load and appropriately streamlined clinical practices) than are freestanding pediatric hospitals. This was demonstrated in Canada by Shah et al,9 who found that outborn premature infants who were admitted to perinatal centers had lower risks of death and morbidities.
It is indisputable that outcome improvements were likely to have been influenced considerably by concomitant advances in neonatal preterm care. It is interesting to note, however, that the reduction in outborn mortality rates was extremely rapid and was evident even during the 18-month washout period (as shown in Fig 2); the speed with which these changes came about is likely attributable to local strategic implementation of the neonatal retrieval service and perinatal advice. The reduction in the number of nontertiary hospital births during epoch 1 did not translate effectively into instantaneously increased numbers of NICU survivors. This lack of apparent effectiveness in epoch 1 could be attributable to a very high inherent mortality rate in this gestational age range and also to less well-coordinated perinatal advice and retrieval. Indeed, in the difference-in-differences analyses, morbidities such as intraventricular hemorrhage and necrotizing enterocolitis showed improvement that exceeded that for inborn infants. This is vitally important, because these morbidities have all been implicated in the development of adverse neurodevelopmental outcomes. The higher rate of chronic lung disease is likely related to the increased survival rate.
Whether our findings can compare directly with those for other countries is difficult to ascertain, because NSW has a much lower outborn rate than many other countries, such as the United States, where the Vermont Oxford Network data showed significantly higher (albeit decreasing) outborn rates for very low birth weight admissions from 1991 (20.5%) to 1999 (16.1%).28 Despite this, the benefits of regionalizing perinatal services for premature infants have been demonstrated repeatedly,27 and the NSW strategies described in this article might have worldwide implications in developed and developing countries. For example, it would be interesting to see whether our results could be duplicated in the Canadian network with destination preference changes.
Unfortunately, there were unavoidable weaknesses and gaps in our data. For example, we did not have detailed information on the quality of perinatal care, resuscitation or treatment at delivery, or stabilization procedures before and during transport at community hospitals. The Midwives Data Collection, which is usually completed at the time of discharge of the mother from hospital, could not provide reliable data on ultimate nontertiary hospital mortality rates. Information on whether the infant died before retrieval was not available for the first epoch, to allow for comparisons. These and other unmeasured factors might have confounded our findings.
| CONCLUSIONS |
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| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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Address correspondence to Kei Lui, MBBS, FRACP, MD, Department of Newborn Care, Royal Hospital for Women, Barker St, Randwick, NSW 2031, Australia. E-mail: kei.lui{at}sesiahs.health.nsw.gov.au
The authors have indicated they have no financial relationships relevant to this article to disclose.
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