Healthcare is generally purchased through a third party

Healthcare is generally purchased through a third party, an insurance company or the government.  The purchase of most items is done directly, without a third party (you go to the grocery store and make purchases, the transaction is between you and the store).

In your opinion, how does the purchase through a third party affect the use of healthcare.  Does it increase use, decrease use, or have no effect?  Clearly explain your reasoning and be specific.