The 2006 signing ceremony for the Massachusetts health-care law that inspired the Affordable Care Act. (AP Photo/Elise Amendola, File)

The landmark 2006 Massachusetts health-care law that inspired the federal overhaul didn't lead to a reduction in unnecessary and costly hospitalizations, and it didn't make the health-care system more fair for minority groups, according to a new study that may hold warnings for the Affordable Care Act.

Massachusetts’ uninsured rate was cut by half to 6 percent in the years immediately following the health-care law signed by then-Gov. Mitt Romney. Blacks and Hispanics, who have a harder time accessing necessary medical care, experienced the largest gains in insurance coverage under the Massachusetts law, though they still were more likely to be uninsured than whites.

The new study, published in the BMJ policy journal, examined the rates of hospitalizations for 12 medical conditions that health-care researchers say wouldn't normally require hospitalization if a patient has good access to primary care. These include hospitalizations for minor conditions like a urinary tract infection, or chronic conditions that would require repeat primary care visits over the course of a year.

"It's thought to be a good measure and one of the few objective ways of looking at access [to health-care provider] in the community," said Danny McCormick of Harvard Medical School, the study's lead author.

McCormick, along with Boston University School of Medicine researchers, looked at every single such hospital admission in Massachusetts in almost two years before and after the state's health-care law was enacted. They compared the results to three control states — New Jersey, New York and Pennsylvania — that didn't have a similar coverage scheme.

You would probably expect that more people having insurance means better access to primary care, meaning fewer people who would be hospitalized for avoidable conditions. However, the rates of preventable hospitalizations were practically the same in the first few years of the Massachusetts health reform, the researchers found. Further, blacks and Hispanics continued to have higher rates of hospitalization, and the disparity gap didn't narrow in a meaningful way.

"Because the national reform is really closely based on the Massachusetts reform, the results are concerning," said McCormick, also a primary care physician with the Cambridge Health Alliance system.

The study's authors offer a few explanation for the results, some that pertain to Massachusetts specifically. The state already had a relatively low rate of uninsured before the reform and a robust safety net serving the uninsured — so the reform may have had little affect on how the state's residents accessed care. The effects might have been greater in a state with a higher rate of uninsured individuals.

The findings, though, might emphasize deeper shortcomings in the health-care system that an insurance card alone won't fix. Out-of-pocket costs for doctor visits and drugs may be preventing many of the newly insured from affording necessary primary care that would have otherwise kept them out of the hospital. Patients may have a hard time finding a doctor. And there are socioeconomic factors at play, like fewer community resources and lower levels of literary and English proficiency among the uninsured.

But the country's health-care system is the midst of transforming from one that rewards doctors for treating people when they get sick to one that rewards doctors for keeping patients healthier in the first place. That's resulted in experiments that are better targeting patients in their communities and ensuring they receive care before their conditions worsen.

"Ten years ago, we wanted patients to show up — it was all upon the patient," McCormick said. "Now there's much more recognition of all the social factors that influence whether patients can get the care they need."