Comparison of Mortality and Morbidity of Very Low Birth Weight Infants Between Canada and Japan

OBJECTIVE: To compare neonatal outcomes of very low birth weight (VLBW) infants admitted to NICUs participating in the Canadian Neonatal Network and the Neonatal Research Network of Japan.

METHODS: Secondary analyses of VLBW infants in both national databases between 2006 and 2008 were conducted. The primary outcome was a composite of mortality or any major morbidity defined as severe neurologic injury, bronchopulmonary dysplasia, necrotizing enterocolitis, or severe retinopathy of prematurity at discharge. Secondary outcomes included individual components of primary outcome and late-onset sepsis. Logistic regression adjusting for confounders was performed.

RESULTS: A total of 5341 infants from the Canadian Neonatal Network and 9812 infants from the Neonatal Research Network of Japan were compared. There were higher rates of maternal hypertension, diabetes mellitus, outborn, prenatal steroid use, and multiples in Canada, whereas cesarean deliveries were higher in Japan. Composite primary outcome was better in Japan in comparison with Canada (adjusted odds ratio [AOR] 0.87, 95% confidence interval [CI] 0.79–0.96). The odds of mortality (AOR 0.40, 95% CI 0.34–0.47), severe neurologic injury (AOR 0.57, 95% CI 0.49–0.66), necrotizing enterocolitis (AOR 0.23, 95% CI 0.19–0.29), and late-onset sepsis (AOR 0.22, 95% CI 0.19–0.25) were lower in Japan; however, the odds of bronchopulmonary dysplasia (AOR 1.24, 95% CI 1.10–1.42) and severe retinopathy of prematurity (AOR 1.98, 95%CI 1.69–2.33) were higher in Japan.

CONCLUSIONS: Composite outcome of mortality or major morbidity was significantly lower in Japan than Canada for VLBW infants. However, there were significant differences in various individual outcomes identifying areas for improvement for both networks.