People with low incomes have benefited in key ways from the Affordable Care Act and Medicaid expansion, but without further federal and state health care policy revisions, millions of U.S. citizens will not receive the medical attention they need to truly improve their health.

That's the conclusion of a recent study directed by David Levine, M.D. with Brigham and Women's Hospital in Boston. Levine's team set out to examine "the association of the ACA with changes in high-value care, low-value care, patient experience, utilization, and cost."

They analyzed medical data from nearly 125,000 patients, comparing responses and care outcomes from two groups before the ACA's adoption and after. The first group — the primary focus of the study — had incomes of less than 400% of the federal poverty level (FPL). The second had incomes of 400% of FPL or greater.