Population size and urban health advantage: scaling analyses of four major diseases for 417 US counties

In order to test the validity of urban health penalty versus urban health advantage, we have selected four major non-communicable diseases, cancer, circulatory, respiratory, and endocrine, nutritional and metabolic (ENM), to determine their scaling relationship between death counts and population size for nearly 400 large urban counties in the US during 1999 to 2010. We discover that there is a super-linear scaling relationship for the total counties for each of the four diseases categories, indicating urban health penalty. However, the results from our analysis by the subgroups of counties with different population sizes yield a U-shaped scaling curve where the most pronounced sub-linear relationship occurs at the subgroup of top 40 most populous counties. In short, both super-linear and sub-linear scaling relationships are observed depending on the subgroups with varying population sizes. Incorporating additional control variables do not materially alter our findings.