Neighbourhood Income Level and Outcomes of Extremely Preterm Neonates: Protection Conferred by a Universal Health Care System

OBJECTIVES: To determine the impact of neighbourhood income and maternal residence population density on mortality and various morbidities at discharge or transfer from the NICU among extremely preterm neonates (<27 weeks gestation) in Canada. METHODS: Neighbourhood income level and residential status was derived using a postal code conversion file and census data. Multivariable logistic regression analysis was used to estimate the risk-adjusted odds ratio (AOR) of mortality and survival without major morbidities (chronic lung disease, necrotizing enterocolitis, severe intraventricular hemorrhage, and retinopathy of prematurity) among 2,752 extremely preterm infants admitted to 25 tertiary level neonatal intensive care units in Canada between 2007 and 2008. RESULTS: There were no significant differences between mothers from different neighbourhood income quintiles (Q1 = low; Q5 = high) and neonatal mortality AOR (95% confidence interval): Q1: 1.10 (0.74-1.62), Q2: 1.00 (0.67-1.49), Q3: 1.39 (0.93-2.07), Q4: 1.01 (0.67-1.52), Q5: 1 (reference); or survival without major morbidity: Q1: 1.01 (0.70-1.44), Q2: 0.84 (0.58-1.23), Q3: 0.85 (0.58-1.24), Q4: 0.92 (0.63-1.35), Q5: 1 (reference). There were no significant differences in mortality (AOR 1.14 [0.83-1.57]) or in survival without major morbidity (AOR 0.92 [0.67-1.26]) between infants of mothers residing in sparsely populated areas compared to densely populated areas. CONCLUSION: Maternal residence in a low-income neighbourhood or sparsely populated area was not associated with higher odds of mortality or survival free of major morbidities in extremely preterm infants.