Socioeconomic inequalities in childhood mortality from congenital heart defects: need for internal comparison cohort

Abstract

BackgroundAn increasing proportion of children with congenital heart defects survive into childhood. Since study populations typically do not contain children without such defects, how survival compares with the general population is unknown. Whereas socioeconomic inequalities in child mortality persist in the general population, such inequalities have not been investigated in children with congenital heart defects. We estimated postneonatal mortality in children with congenital heart defects by socioeconomic status and assessed whether inequalities differed from those in children without major congenital anomalies. MethodsA population-based cohort of 264 247 children born 1990–09 was constructed from the Health Improvement Network, a UK database of prospectively collected primary care records. Diagnoses of major congenital anomalies were classified with the European Surveillance of Congenital Anomalies criteria. Socioeconomic status was measured by quintiles of the Townsend Index of Deprivation, a nationally standardised ranking of area-level material deprivation. Mortality rates (age 1 month to 5 years) were calculated per 1000 person-years for children with congenital heart defects and for those without major congenital anomalies, stratified by socioeconomic status quintile; mortality rate ratios (MRRs) were used to compare risk between each population by quintile. The stratified log-rank test was used to test whether MRRs differed by socioeconomic status. FindingsAmong 2012 children with congenital heart defects, mortality was 6·4 per 1000 person-years (95% CI 4·9–8·6). Rates were lowest in the least deprived quintile (4·26/1000, 2·13–8·51) and rose with each quintile to 12·33/1000 (7·00–21·7) in the most deprived quintile. Risk of death in children with congenital heart defects was 20 times higher than in those without major congenital anomalies (MRR 20·0, 95% CI 14·8–27·2). However, the effect of socioeconomic status on mortality was similar between children with congenital heart defects and those without major congenital anomalies (stratified log-rank test p=0·891). This non-statistically significant result might have resulted from insufficient sample size to generate precise mortality risk ratios. InterpretationDeprivation was associated with an increased risk of death in children with congenital heart defects and without major congenital anomalies, but no evidence was found to suggest that the association with socioeconomic status was different between the two populations. These findings highlight the need to target health inequalities in children with congenital heart defects as well as in the general population. FundingRS is supported by a post-graduate scholarship from the Economic and Social Research Council.