Does household income predict health and educational outcomes in childhood better than neighbourhood deprivation?

Background Public health research and prevention policies often use the small area Index of Multiple Deprivation (IMD) at neighbourhood level to proxy individual socio-economic status because it is readily available. We investigated what household income adds to IMD in early childhood for predicting adverse health in adolescence. Methods Using data from the Millennium Cohort Study, we analysed IMD and self-reported equivalised household income (ages 0-5) to predict outcomes at age 17: poor academic achievement, psychological distress, poor health, smoking, and obesity. Predictions were compared using IMD quintiles alone, household income alone, and both together. Results Household income was a stronger and more consistent predictor of age 17 outcomes than IMD and revealed inequalities within neighbourhoods. Decreasing household income showed steep gradients in educational attainment and smoking across all IMD quintiles, and moderate gradients in obesity, psychological distress, and poor health in most quintiles. IMD did not predict smoking or psychological distress within any income group, or educational attainment within the poorest income group. Conclusion Household income is associated with inequality gradients within all quintiles of neighbourhood IMD. Early childhood public health strategies should consider household income in combination with neighbourhood deprivation.