On average, the US outspends its peer countries in healthcare by a large amount.  Almost 18 percent of GDP is spent on healthcare, which is 6% more than the Netherlands which is the next highest spender.  This amounts to about 1 trillion dollars, or $8000 per household. There are multiple reasons for this phenomenon.  First of all,  the US offers a more expensive range of services.  The US has a number of specialized healthcare providers which usually cost a bit more.  More amenities and quicker response time are all great perks, but they cost more as well.  Another reason for the more expensive mix in the U.S. is it produces more income for drug manufacturers, specialist physicians, and others who have considerable influence on policy. The price of branded prescription drugs are also about 2x the price of those in other countries.  

There are many other reasons for the increased prices as well, and economists are doing research.  Some hope the Affordable Care act will remedy these high costs in the long run, but nobody can predict for sure.

Source:

http://www.theatlantic.com/business/archive/2014/07/why-do-other-rich-nations-spend-so-much-less-on-healthcare/374576/