Economists at the Organization for Economic Cooperation and Development, a think tank in Paris bankrolled by 30 developed countries from Australia to the U.S., are waving a red flag.

And even if governments somehow find a way to eliminate that extra one percentage point of spending growth, the OECD expects public spending on health care, including long-term care for the elderly, to reach 10% of GDP on average. The projected increases are sharp even in countries that have kept overall spending on health care far below the U.S., which spends more per person and a greater fraction of its GDP on health care than any other country.

In most OECD countries, including Canada and Britain, health-care systems are financed primarily through taxes. In the U.S., by contrast, about 55% of the health-care bill is paid by individuals and their employers. Yet U.S. government spending on health care -- mainly Medicare and Medicaid -- amounts to an above-average 7.2% of GDP. (Overall U.S. health-care spending, private and public, this year is projected to equal 16.2% of GDP.)