The rate of neurodevelopmental impairment (NDI) in infants born ≤500g in Japan between 2003-2012 was 59%, and the prevalence of NDI did not significantly change over the 10-year period.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Survival rates for periviable infants have improved over the past decade, but data on rates of neurodevelopmental disabilities in this population vary by study. Accurate data on long-term neurodevelopmental outcomes is critical for families and physicians to make informed decisions regarding resuscitation and care of these infants. The purpose of this study was to describe 3-year neurodevelopmental outcomes in infants born ≤500g registered in the Neonatal Research Network of Japan (NRNJ). The overall rate of NDI in this cohort was 59%, while rates of cerebral palsy (CP), visual impairment, hearing impairment, and cognitive impairment were 22.2%, 21.3%, 4.3%, and 48.2%. There were no significant changes in the prevalence of NDI and no disability over the 10-year study period. NDI was also significantly associated with cystic periventricular leukomalacia (cPVL), severe necrotizing enterocolitis (NEC), patent ductus arteriosus (PDA) ligation, and male sex. GA and BW were not associated with a higher adjusted risk ratio (aRR) of NDI. Limitations of this study included a homogenous population, attrition (which may have reduced power to detect the effects of GA or BW on NDI), and lack of comparison to term born infants. Data from this study should prompt targeting white matter injuries in perinatal medicine to improve developmental outcomes.
In-Depth [prospective cohort]: Out of 1613 infants ≤500g registered in the NRNJ, 460 (56.7%) had follow-up data at 36-42 weeks for analysis. Exclusion criteria included death in the delivery/operating room, transfer to outside hospital, GA <22 weeks, and unavailable mortality records during NICU stay. Median GA was 24 6/7 weeks (range = 22 0/7-33 2/7) and median BW was 462g (range = 267-500g). Primary outcomes included NDI, defined as CP, visual or hearing impairment, or cognitive impairment. Cognitive impairment was defined as a developmental quotient (DQ) score of <70 using the Kyoto Scale of Psychological Development. The proportions of NDI, CP, visual impairment, hearing impairment, and cognitive impairment in the entire cohort were was 59.1% (95%CI =54.6-63.5%), 22.2% (95%CI =54.6-63.5), 21.3% (95%CI =17.7-25.3), 4.3% (95%CI =2.7-6.8%), and 48.2 (95% CI =43.5-52.8%), respectively. Overall, 80 children (17.4%) had no disability. The study group was also stratified into 2 weight groups: ≤400 (n=65) and 401-500g (n=395). There were no significant differences in rates of NDI between the 2 groups, but cognitive impairment was significantly higher in the ≤400g group compared to the 401-500g group (60.7% versus 46.2, P = 0.04). NDI and no disability remained unchanged in their prevalence (P=0.70 and 0.78, respectively) over the 10-year study period. NDI was significantly associated with severe IVH (aRR=1.42, 95%CI =1.19-1.68, P <0.01), cPVL (aRR =1.40, 95%CI =1.13-1.73, P <0.01), severe NEC (aRR =1.31, 95%CI =1.07-1.60, P <0.01), PDA ligation (aRR=1.29, 95%CI =1.09-1.54, P <0.01), and male sex (aRR =1.19, 95%CI =1.01-1.40, P=0.04) in multivariate regression analysis.
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