Determinants of under-5 mortality among the poor and the rich: a cross-national analysis of 43 developing countries

Background Under-5 mortality is unacceptably high in many countries, the burden of which is mainly borne by the poor. Whereas country characteristics are known to influence under-5 mortality, it is unknown whether these have a different impact on the poor and the rich. We aimed to describe how the association between under-5 mortality and socioeconomic, political, and health care factors varies in strength between richer and poorer children. Methods Cross-national analysis of 43 developing countries using wealth-group specific under-5 mortality rates as outcome. Relative effects were estimated using OLS regression; differences in associations between wealth groups were tested. Results Higher national incomes were associated with lower under-5 mortality rates. This association was significantly weaker for the poor compared with the rich (P = 0.014). Ethnic fragmentation was significantly more strongly associated with higher under-5 mortality among the poor compared with the rich (P = 0.027). The association between public spending on health and under-5 mortality was stronger for the poor (P = 0.0001). Skilled delivery attendance and immunization coverage among the poor were significantly more strongly related to public spending on health than such health care use among the rich (P = 0.0001 and P = 0.045, respectively). No differentials in the relative effect of female literacy, democracy, and state strength were observed. Conclusion Our results suggest that economic growth is associated with widening poor-rich disparities in under-5 mortality. Increased public spending on health might partly remedy this effect.