Six years after former Gov. Mitt Romney implemented his health care overhaul in Massachusetts, it seems to be going strong. Romney’s successor, Democrat Deval Patrick, calls the legislation “a terrific success.” Last year, an attempt to repeal the “individual mandate” — the part that requires most people to have insurance — couldn’t get enough signatures. Meanwhile, a new study in the journal Health Affairs shows that more Massachusetts citizens are seeing a doctor regularly, fewer are going to emergency rooms for care, and the percentage who rate their own health as “good” or “excellent” is going up. And health costs are starting to drop, too. Two years ago, Gov. Patrick directed his insurance commissioner to utilize a little-used power to turn down a requested rate increase because it was excessive. Insurers were outraged — but then they started negotiating. Now, instead of agreeing to annual reimbursement requests of 8–10%, they’re working with 3%, 2%, or even 0% increases.