Where is the gap?: the contribution of disparities within developing countries to global inequalities in under-five mortality

Background: Global health equity strategists have previously focused much on differences across countries. At first glance, the global health gap appears to result primarily from disparities between the developing and developed regions. We examine how much of this disparity could be attributed to within-country disparities in developing nations. Methods: We used data from Demographic and Health Surveys conducted between 1995 and 2010 in 67 developing countries. Using a population attributable risk approach, we computed the proportion of global under-five mortality gap and the absolute number of under-five deaths that would be reduced if the under-five mortality rate in each of these 67 countries was lowered to the level of the top 10% economic group in each country. As a sensitivity check, we also conducted comparable calculations using top 5% and the top 20% economic group. Results: In 2007, approximately 6.6 million under-five deaths were observed in the 67 countries used in the analysis. This could be reduced to only 600,000 deaths if these countries had the same under-five mortality rate as developed countries. If the under-five mortality rate was lowered to the rate among the top 10% economic group in each of these countries, under-five deaths would be reduced to 3.7 million. This corresponds to a 48% reduction in the global mortality gap and 2.9 million under-five deaths averted. Using cutoff points of top 5% and top 20% economic groups showed reduction of 37% and 56% respectively in the global mortality gap. With these cutoff points, respectively 2.3 and 3.4 million under-five deaths would be averted. Conclusion: Under-five mortality disparities within developing countries account for roughly half of the global gap between developed and developing countries. Thus, within-country inequities deserve as much consideration as do inequalities between the world's developing and developed regions.