Scientists and sociologists have been tabulating these numbers for decades. There is no doubt about this. If anything, the numbers are underreported due to potential legal liability. The US healthcare system is (by the hard data) far worse than just about any other wealthy country on earth and we have by far and away the most costly care-- but the quality just isn't there and it continues to FALL bearly every year while prices are, by global standards, simply insane and unjustifiable.
Tom Petty was taking a lot of medications-- this made him especially vulnerable to toxic drug interactions.
Even wealthy rock stars aren't safe in a system like ours. And you can take that to the bank.