Since I am a health economist, I can tell you that it is subject to many of the same problems other goods face: prices increase and this is generally observable (though much harder in healthcare than other areas!), while quality improves all the time but measuring quality is quite hard, perhaps also harder than in other classes of goods.
https://www.bls.gov/cpi/factsheets/medical-care.htm
Since I am a health economist, I can tell you that it is subject to many of the same problems other goods face: prices increase and this is generally observable (though much harder in healthcare than other areas!), while quality improves all the time but measuring quality is quite hard, perhaps also harder than in other classes of goods.