The inflation of medical expenses in the US significantly outpaces the standard measures of inflation that you're quoting, generally by at least 3%. The OPs estimate of $500 is much closer to reality than yours.
Quoting a factoid about the distribution of actual medical _spending_ doesn't change the incorrectness of projecting CPI onto medical _costs_. There are indices - the BLS maintains one and a number of actuarial firms publish others - that track the costs of various medical services and they all outpace CPI.
You're right, there are a lot of factors at play here, its not a simple issue, and both myself and OP were somewhat oversimplifying things on opposing ends of the spectrum. My point though is that simply looking at the increase in the cost of medical services across the board is different than looking at how much the average American family is actually spending on medical costs year over year, and that is a key differentiation.
Medical expenses are going up much faster than inflation. At least 4% annually I think. Maybe as much as 6-8% on average since 2013? I see varying figures, but definitely not 0-2%.
Average increases in nationwide medical expenses and inflations' effect on the average household are completely separate issues because the sickest 5 percent of the population consume 50 percent of total health care costs. The healthiest 50 percent only consume 3 percent of the nation's health care costs.