Conducted by Benjamin Sommers (Harvard University), Sharon Long (Urban Institute), and Kate Baicker (Harvard University), this study compares Massachusetts counties to similar counties in the United States before and after the enactment of RomneyCare in 2006. Consistent with similar studies, the authors found that when RomneyCare expanded health insurance coverage, consumption of medical services increased. They also find that relative to the rest of the country, mortality among adults age 20-64 in Massachusetts dropped by 2.9 percent, while mortality from causes treatable by medical care fell by 4.5 percent. The below chart shows how mortality rates in Massachusetts diverged slightly from the control group starting in 2006.
As one might expect, most of the reduction in mortality occurs among those age 35-64.
This study adds to the body of knowledge on the health effects of government-initiated coverage expansions. A randomized, controlled study called the Oregon Health Insurance Experiment failed to detect any improvement in measured physical health outcomes after Oregon expanded its Medicaid program, but the study has been criticized for being too small to notice such effects. Larger but less well-controlled studies like this one have found that expanding Medicaid is associated with health improvements. The most important feature of that literature is how sparse it is.