Date Published: January 23, 2017
Publisher: Public Library of Science
Author(s): Jae Hyun Park, Yun Sil Chang, Sein Sung, So Yoon Ahn, Won Soon Park, Nick Gay.
To investigate the trends in mortality, as well as in the timing and cause of death, among extremely preterm infants at the limit of viability, and thus to identify the clinical factors that contribute to decreased mortality.
We retrospectively reviewed the medical records of 382 infants born at 23–26 weeks’ gestation; 124 of the infants were born between 2001 and 2005 (period I) and 258 were born between 2006 and 2011 (period II). We stratified the infants into two subgroups–“23–24 weeks” and “25–26 weeks”–and retrospectively analyzed the clinical characteristics and mortality in each group, as well as the timing and cause of death. Univariate and multivariate logistic regression analyses were done to identify the clinical factors associated with mortality.
The overall mortality rate in period II was 16.7% (43/258), which was significantly lower than that in period I (30.6%; 38/124). For overall cause of death, there were significantly fewer deaths due to sepsis (2.4% [6/258] vs. 8.1% [10/124], respectively) and air-leak syndrome (0.8% [2/258] vs. 4.8% (6/124), respectively) during period II than during period I. Among the clinical factors of time period, 1-and 5-min Apgar score, antenatal steroid identified significant by univariate analyses. 5-min Apgar score and antenatal steroid use were significantly associated with mortality in multivariate analyses.
Improved mortality rate attributable to fewer deaths due to sepsis and air leak syndrome in the infants with 23–26 weeks’ gestation was associated with higher 5-minute Apgar score and more antenatal steroid use.
Recent improvements in perinatal and neonatal intensive care have resulted in improved survival in extremely preterm (EPT) infants near the limit of viability [1–7]. Nonetheless, EPT infants remain at the highest risk of neonatal and infant mortality worldwide [8,9]. Active treatment in infants born at or less than 24 weeks’ gestation varies widely between hospitals; in turn, there are broad inter-center differences in the survival of these infants . As the decision for providng active treatment for these EPT infants is now usually indivisualized based on the shared-decision making by parents, statistics derived from populations including large numbers of EPT infants without active treatments might mispresent the infants’ chances of survival, and thus misguide the parents to forgo initiating active lifesaving intervention. Therefore, providing the most recent outcome data of EPT infants receiving active treatments is important to counsel families, and support their decision for providing active treatments to all these EPT infants . The findings of this study that all EPT infants admitted to our hospital received active treatment also support the importance of providing accurate survival data for parental counseling. Furthermore, survival in infants near the limit of viability has been improved by active treatment policies, without a concomitant increase in morbidity among survivors [4, 11–15]. Taken together, these findings suggest that active treatments of EPT infants are more beneficial than harmful.
Data collection was approved by the Institutional Review Board of Samsung Medical Center, who waived the requirement for informed consent in this retrospective chart review (IRB No. SMC 2016-03-121). We retrospectively reviewed the medical records of 382 preterm infants who were born at 23 and 26 weeks’ gestation and admitted to the neonatal intensive care unit (NICU) at Samsung Medical Center; 124 of the infants were born between January 1, 2001 and December 31, 2005 (period I), while 258 were born between January 1, 2006 and December 31, 2011 (period II). The study period was divided on the basis of changes in the survival rate of these EPT infants. We compared overall mortality, as well as timing and cause of death, between the two time periods. In admission, we compared the proportionate cause-specific mortality rate in terms of timing of death between the two time periods.
Mortality rates in EPT infants have been declining incrementally during the past decades due to continuing improvements in perinatal and neonatal intensive care [1–7]. However, it remains uncertain whether survival rate has improved beyond 23–24 weeks’ gestation [9, 25]. Recently, several studies reported that active lifesaving treatments improved mortality rates in EPT infants at the known verge of viability [4, 11–15]. Indeed, inter-center differences in the mortality of EPT infants at the verge of viability are primarily due to variations in the active perinatal and neonatal treatment of these most immature infants . In the present study, while active treatments were applied to all EPT infants throughout the study periods, we observed significantly much more improved mortality rates–from 51.8% to 22.5% during last decade–in EPT infants, especially in those who were born between 23 to 24 weeks’ gestation. Therefore, our current data about the mortality rate in these infants might inform guidelines for the care of these most immature infants, as well as improve the counseling that families receive regarding the infants’ survival [1, 26]. Furthermore, provision of better perinatal and neonatal intensive care significantly improved 5 min Apgar score and reduced sepsis and air leak syndrome besides active life saving treatments would also much more improve the mortality of the EPT infants. Taken together, these findings suggest that the limit of viability in EPT infants is not static, and that it could be much more improved not only with active treatments but also with better perinatal and neonatal intensive care .