This is a big part of it - the major part.  Health care is more expensive now because it does a lot more now.   Thirty years ago, someone with inoperable cancer would basically be told to go home and die.  Today, they can go through innumerable rounds of chemo, radiation, drug therapies, repeated CT scans, etc.   Thirty years ago, someone with high cholesterol would be told to watch his or her diet and sent home.  If that person had a heart attack, he or she was much more likely to die.
Today, if you have high cholesterol, you can be put on Lipitor or other similar drugs.  Angiograms can determine if you have plaque buildup in your arteries, and prophylactic treatments like angioplasties can be done - the U.S. leads the world in angioplasties by a wide margin.
If you do have a heart attack, you’re more likely to survive it - and then you may be prescribed with beta blockers and other post-attack preventative drugs, and perhaps go in for bypass surgery.
Thirty years ago, if your baby was born several months premature, it would almost certainly die.  Today, it may survive - at a cost of hundreds of thousands of dollars in medical care.
Three other main reasons why medical costs are increasing:  The aging of the population, the wealth of the population, and the 3rd party payment system in the U.S. which removes cost-containment incentives.
Most people’s health care expenses come with old age.  As the population ages, health care costs increase.  This is going to be a big problem in the U.S. as the baby boom retires.
Wealthy populations spend a greater proportion of GDP on health care because they can afford it.  The U.S. spends the highest percentage of its GDP on health care.  But then, it also spends the highest proportion of GDP on pets, manicures, toys, cable TV, and other luxuries.
And a system in which insurance is expected to cover 100% of your costs is a system in which the only thing that controls those costs is paperwork and insurance company regulation of services.  Consumers and doctors have no incentive to control costs, leaving that control to the one agency least-equipped to do so.