Less than our spending on it would suggest, according to an infographic from the the Bipartisan Policy Center:
Austin Frakt disbelieves the numbers:
David Cutler and others suggest that health care is responsible for 50% of the gains in longevity over the past half century. Now, I have not read the underlying literature on this. … Still, it seems to me there is no good reason to accept the 10% figure at the top of the left-hand side of the infographic. I’d like to know more how it got there. I’d like to hear the best argument as to why it’s correct.
Ezra Klein explains why our health dollars aren't spent more wisely:
In 2009, I argued that one of the biggest impediments to spending money on programs that make people healthier — such as, oddly enough, early childhood education — is that we’re spending so much money taking care of people when they’re sick. The piece holds up pretty well, I think.
Yglesias looks at the issue from another angle:
The rural/metro health care gap is … a pretty good case study in the limited relevance of health care services to health outcomes. Residents of the extremely low density northern plains states have some of the highest life expectancies in America especially when you consider their relatively low incomes and low levels of educational attainment. That's not because the best doctors in the world are found in Montana or that North Dakota is a good place to find a specialist.