Re-evaluating the timing of sequential cranial ultrasound screening in very preterm infants for predicting neurodevelopmental outcomes.

Objective: Accurate and early prediction of neurodevelopmental impairment is a crucial endeavor in caring for very preterm infants (<31 weeks' gestation). Sequential cranial ultrasound is the standard of care for the evaluation of preterm brain injury. However, there is no consensus on the timing and frequency of ultrasound screening. At Izaak Walton Killam (IWK) Health Centre, Halifax, Canada, four-time points for routine ultrasound of very preterm infants are performed at weeks 1, 2, 6, and term age. The hypothesis behind this work is that a three-time-point model will be appropriate for neurodevelopmental impairment prognostication.

Materials And Methods: In this retrospective cohort, all very preterm infants (22-30 weeks) born between January 2004 and December 2018 with a neurodevelopmental assessment at 36 months corrected age were included. Three prediction models of neurodevelopmental impairment were compared: 1. A reference model including the gestational age, infant sex, and 2-week and 6-week ultrasound 2. A model including the gestational age, infant sex, and 6-week ultrasound 3. A model including the gestational age, infant sex, and 2-week ultrasound RESULTS: Of 786 eligible preterm infants born during the study period, 656/786 survivors were included in the analysis (mean gestational age 27 weeks, mean birth weight 1,133 g, and 55% male infants). At 36 months of corrected age, 30% developed neurodevelopmental impairment. All three models provided comparable discrimination areas under the curve (AUC) of neurodevelopmental impairment at 36 months of corrected age. Both the 6-week and the reference model had similar AUC of 0.68 (95% CI 0.63-0.72) and were not noticeably different from the 2-week model (AUC 0.66 (95% CI 0.61-0.70)). The 6-week model provided the best prediction with the lowest Akaike information criterion (AIC) of 766 for the 6-week-only model, AIC 769 for combined weeks 2 and 6 (reference model), and AIC 784 for the 2-week-only model.

Conclusion: In this cohort of very preterm infants, a model including 6-week ultrasound only was comparable to a reference model combining 2-week and 6-week ultrasound and showed nearly identical predictive performance of neurodevelopmental impairment at 36 months corrected age across a broad set of metrics; thus, it is redundant to do both the 2-week and 6-week ultrasound.

Clinical Relevance Statement: Late ultrasound at 6 weeks of age provided comparable diagnostic and prognostic information to a reference model combining 2-week and 6-week ultrasound and, if anything, was slightly superior to the 2-week ultrasound model, across a broad set of metrics. The 2-week ultrasound can be eliminated with no impact on the prediction of neurodevelopmental impairment at 36 months, promoting prudent resource allocation and stewardship in healthcare.