Admission temperature and hospital outcomes in extremely preterm infants

Abstract

To evaluate trends in admission temperature and its effect on mortality and short-term morbidities in extremely preterm infants. 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. 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). Admission temperatures improved during the time period. Hypothermia at admission was associated with a significant increase in mortality and NEC.