The group compiled a first-ever "scorecard" that details state-by-state comparisons of the health care experiences of the 39 percent of Americans with incomes less than 200 percent of the federal poverty level, or $47,000 a year for a family of four and $23,000 for an individual.

In the highest-performing states, the report found, low-income, less educated residents are more likely to be covered by health insurance, to have a regular source of medical care and to get recommended preventive care, such as cancer screenings. They also are less likely to die prematurely or end up in the hospital for conditions such as diabetes.

Low-income people account for at least 25 percent of total state populations, and as much as nearly half (47 percent) in some states, including Arkansas, Louisiana, Mississippi and New Mexico.

The report also compared the health care experiences of those with low incomes to those with higher incomes — over 400 percent of poverty, or $94,000 for a family of four — and found "striking disparities by income within each state." The wide differences by geography often put higher-income as well as lower-income families at risk, researchers said.

The report found that higher-income people living in states that lag far behind are often worse off than low-income people in states that rank at the very top of the scorecard. As an example, low-income Medicare beneficiaries in Connecticut and Wisconsin are less likely to receive high-risk medications than higher-income seniors in Mississippi, Louisiana, and Alabama. 

To compile health scores, researchers looked at everything from how many people in a state had health insurance versus those who had none or didn't have enough.

Though researchers noted there was room for every state to improve, states in the Upper Midwest, Northeast, and Hawaii performed best, while Southern and South Central states often lagged.

The report also found that states that have resisted the Patient Protection and Affordable Care Act often scored lower, while states that have embraced all or part of the law tended to score higher. The report didn't analyze the potential effect of PPACA, but it shows that states resisting the law already have among the weakest health safety nets.

For example, states that have opted out of the Medicaid expansion under PPACA have high uninsured rates among low-income adults, such as Texas—where 55 percent of adults with annual incomes below 200 percent of the federal poverty level are uninsured— and Alaska, Florida and Georgia, where uninsured rates for low-income adults are 40 percent or higher.