Duration of inter-facility neonatal transport and neonatal mortality: systematic review and cohort study

Regionalization of perinatal health services has been actively discussed, although important determinants such as effect of duration of neonatal transport on neonatal outcomes have not been investigated well as yet. Therefore the purpose of the present paper was to investigate the association between duration of inter-facility transport and perinatal mortality.

For the systematic review, six major databases were searched. Any comparative studies investigating associations between duration of inter-facility neonatal transport and their outcomes, published in the English language were selected. The studies were screened and reviewed by two independent researchers. For the cohort study, study subjects included every neonate transported to neonatal wards in Osaka, Japan between 1980 and 2000 in an existing surveillance called Neonatal Mutual Cooperative System. They are followed up until 28 days of age, or discharge if earlier. Other variables were also considered as effect modifiers or confounders, including calendar year, birthweight (BW), gestational age (GA), sex, maternal/paternal age, Apgar scores at 1 and 5 min, place of birth and personnel accompanying the neonate during transport (transport personnel), body temperature before transport and on admission, severity of illness, and intraventricular hemorrhage (IVH) grade. Cox regression analyses were performed to obtain principal results, and sensitivity analysis to support them.

Systematic review: only one cross-sectional study conducted in an urban area in India was identified. That study showed that neonates with a long duration of transport had 79% higher odds of death than those transported for a short duration after adjusting for the confounding effects. For the cohort study, among 16 429 subjects, full data were available for 4966 neonates. There was strong evidence that those transported for >90 min had more than twice the rate of neonatal death (rate ratio [RR] 2.26, 95% confidence interval [CI]: 1.26-4.04), and some evidence that those transported for between 60 and 89 min had an 80% higher rate of neonatal death (RR 1.81, 95%CI: 1.07-3.06), both compared with those transported for between 30 and 59 min, after adjusting for the confounding effects. A sensitivity analysis on missing values also supported the results.

There is evidence of an association between duration of transport and increased neonatal mortality, which can be applied to organization of perinatal health services. A prospective cohort study is needed for further investigation.