Laurence J. Kotlikoff and Christian Hagist write,

European critics of the U.S. health care system often focus on the private provision of health care and health insurance. Yet the more important difference between the United States and other developed countries is the failure to control government spending. Other countries employ global budgets and control access to expensive drugs and new technology. The United States, by contrast, has very meager spending controls. If current trends continue, U.S. government health care spending will consume an ever growing portion of national income — far more so than any other developed country.

In other words, our government programs, Medicare and Medicaid, which cover only the old and the poor, are going to be larger as a share of GDP than other countries’ socialized programs that cover everyone. So if we socialize medicine for everyone, we are not going to magically see our spending drop to the share of GDP we see in other countries because of “efficiency.”