The remarkable observation that medical spending has zero net marginal effect is shocking, but not completely unprecedented.
According to Spiegel in "Too Much of a Good Thing: Choking on Aid Money in Africa", the Washington Center for Global Development calculated that it would require $3,521 of marginal development aid invested, per person, in order to increase per capita yearly income by $3.65 (one penny per day).
The Kenyan economist James Shikwati is even more pessimistic in "For God's Sake, Please Stop the Aid!": The net effect of Western aid to Africa is actively destructive (even when it isn't stolen to prop up corrupt regimes), a chaotic flux of money and goods that destroys local industry.
What does aid to Africa have in common with healthcare spending? Besides, of course, that it's heartbreaking to just say no -
Jeff Gray:
It is easy to get blinded by large numbers, but trillions of dollars over 50 years over billions of people is not very much -- just $20 per person per year or so. It is not surprising that this hasn't industrialised the rest of the world over that period of time. It is an enormous problem and even if tackled very efficiently, it will take trillions more before the gap closes. I strongly suggest using 'dollars per person per year' as the unit to see the relative scales of things.