The summary claims, in standard politically-correct fashion: "The U.S. health disadvantage cannot be attributed solely to the adverse health status of racial or ethnic minorities or poor people, since recent studies suggest that even highly advantaged Americans may be in worse health than their counterparts in other countries."
And of course, they don't tell us where these "studies" are. The authors take official statistics reported by governments at face value, statistics which are likely manipulated, as is famously the case for infant mortality. That, and the fact that they blame guns, indicates that this paper is nothing more than politically-motivated propaganda.