Cities and Health: A Response to the Recent Commentaries

We are grateful to our many colleagues who took the time to respond to our analysis of Shanghai’s declining “avoidable mortality.”1 The range of their perspectives across 5 recent commentaries reassures us that the topic is worthy of sustained study. Indeed, the presumption behind our comparative research on healthcare in world cities 2 is that the city is a strategic unit of analysis for understanding the health sector and that world cities share a host of important characteristics. Contrary to Cheng’s 3 comment that we compared“disparate cities whose only common characteristic is that they are of mega-size,” we have relied on a “most similar systems” approach to comparative analysis.4 World cities are characterized by high population size and density, similar commuting patterns between their outer rings and urban cores, and similar functions in the realms of international finance, culture, media, and provision of tertiary and quaternary medical care. Likewise, they exhibit flagrant socioeconomic inequalities, share many of the same strengths and weaknesses, but exist within nations with strikingly different health policies.