Wide international variation in survival for periviable neonates

1. Survival of neonates born at 22 weeks’ gestation ranged from 1.8 to 22.3% using all live births as the denominator, and this variation declined when incorporating births categorized as stillborn or liveborn surviving beyond 12 hours of life.

Evidence Rating Level: 4 (Below Average)

Study Rundown: Gestation-specific survival rates inform how clinicians provide perinatal counseling for families faced with the possibility of extremely preterm birth between 22-25 weeks’ gestational age. While standard neonatal survival rates include the number of live births as the denominator, international variations exist in the registration of periviable neonates as stillborn versus liveborn. The purpose of this study was to evaluate international differences in the case classification of births 22-25 weeks’ gestation and how those differences subsequently affect survival data. Study findings demonstrate that variation in international rates of neonatal survival to 28 days was most variable when using all live births or live births surviving to 1-12 hours of life as the denominator. For infants 22-25 weeks’ gestation, there was also wide international variation in their classification as stillbirths. These variations declined when considering stillbirths or live births surviving beyond 12 hours of life in the denominator. The authors hypothesized that while reported proportions of live and stillbirths may reflect true differences, they may also be reflective of differences in perceived viability. Such variation in classification of births, if due to reporting biases, should prompt greater collaboration to decrease variations in data collection and case definitions so that clinicians may offer more accurate perinatal counseling.

Click to read the study, published today in Pediatrics

Relevant Reading: Neonatal outcomes of very low birth weight and very preterm neonates: an international comparison

In-Depth [cross-sectional study]: Data was reviewed from national registries in 7 developed countries, including the United States (2014; N=11,144), Canada (2009-2014; N=5668), the United Kingdom (2014-2015; N=2992), Norway (2010-2014; N=409), Finland (2010-2015; N=348), Sweden (2011-2014; N=489) and Japan (2014-2015; N=2288). Births were categorized as stillbirth (antepartum vs. intrapartum vs. unknown time) or livebirth ending in surviving 1 hour, 24 hours 7 days, and beyond 28 days. The primary outcome was survival rate (beyond 28 days) using the standard model versus using the aforementioned categorizations as the denominator in calculated survival. In terms of general classification of births, the proportion of reported live births for neonates 22 weeks’ gestation ranged from 25.7% (Norway) to 53.3% (Canada), and these percentages increased with increasing gestational age. At 22 weeks’ gestation, the proportion of reported intrapartum stillbirths ranged from 11.9% (Finland) to 23.1% (United Kingdom), and these percentages declined with increasing gestational age. At 22 weeks’ gestation, the proportion who survived to 28 days ranged from 1.8 to 22.3%. This variation in survival persisted up until survival at 12 hours of life, at which point variation declined with survival thereafter. This trend in 28-day survival was mirrored by births at 23 weeks’ gestation. Variation in survival was the greatest when the denominator included all live births or infants surviving at least 1 hour, while variation decreased when including stillbirths or infants that survived beyond 12 hours.

Image: PD

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