Most music industry professionals (if not most people) I seem to know don't have health insurance (myself included). They rely on emergency safety nets like Musicares and Sweet Relief after the fact. While it's great that these organizations exist, they can't single-handedly solve the issue of access to preventative care.
Tragically, it sounds like this harsh reality factored into the recent death of Big Star leader Alex Chilton. According to his wife (via this heartbreaking article in New Orleans-based paper The Times-Picayune), Chilton had been complaining from chills and shortness of breath during the week prior to his fatal heart attack. He didn't seek care because he didn't have insurance.
Locally, we do have one decent resource for preventative care for artists of all disciplines, namely the voucher program through the Artists' Trust. Though funding caps at $150 per person, it's still better than nothing. The program is set to expire in June of 2010, so definitely check it out soon if you want to take advantage of it.