By Maggie Fox, Health and Science Editor

WASHINGTON, Jan 6 (Reuters) - Americans spent $2.2 trillion on healthcare in 2007, or $7,421 per person, according to a U.S. government report released on Tuesday.

The 6.1 percent rate of growth over 2006 was the lowest since 1998, mostly because growth in spending on drugs slowed, the team at the Centers for Medicare and Medicaid Services found.

Cheaper generic drugs and worries about drug safety helped slow spending growth but the numbers kept the United States far ahead of all other countries on health spending.

Health spending represented 16.2 percent of U.S. gross domestic product, up slightly from 16 percent in 2006, the researchers reported in the journal Health Affairs.

"Slower spending growth for prescription drugs was one of the major factors driving down overall healthcare spending growth in 2007," Micah Hartman, a statistician at CMS who worked on the report, told reporters in a telephone briefing.

"In 2007, retail prescription drug spending increased 4.9 percent to $227.5 billion; this was a deceleration from 8.6 percent growth in 2006," the CMS team wrote.

Some of this loss hit drug companies.

Sanofi (SASY.PA: Quote, Profile, Research) sleeping pill Ambien, Coreg, a heart failure drug made GlaxoSmithKline (GSK.L: Quote, Profile, Research) (GSK.N: Quote, Profile, Research) and Pfizer Inc's (PFE.N: Quote, Profile, Research) blood pressure drug Norvasc all lost patent exclusivity in 2006, making room for less expensive generics.