What happened in 1980?

Health Care Costs as a percent of GDP vs Year with US Presidential Terms

Health care costs as percent of GDP vs year along with US presidential terms. This data graphic shows that before the 1980s the US was not terribly out of line with other OECD countries. US health care costs spiked in remarkably similar way with both Bush presidencies.

From here.

Megan McArdle proposes an answer here.