The end of the millennium development goals (MDGs) in 2015 marked a turning point in addressing some of the world’s most pressing and complex development challenges outlined in 2000 by the global development community. The goals, which were designed to mobilize global attention around eight priority development issues, were unprecedented in both scale and pace. Their implementation has led to significant achievements including a decline in mortality from tuberculosis and human immunodeficiency virus (HIV) infections, a decline in child and maternal mortality and improved access to safe drinking water and sanitation. These achievements show that many of the goals have been met. ¹ However, the MDGs and their focus on aggregate-level measures of progress masked the inequalities in health outcomes that existed between and within countries, regions and subgroups in a given population. ^{2 , 3}