Many states would face substantial primary-care capacity challenges if Medicaid eligibility expands in 2014, as called for under the Patient Protection and Affordable Care Act, says a new article released online recently in the New England Journal of Medicine.

The status of the health reform law is in flux, following rulings by two federal judges that it was unconstitutional for Congress to enact a law that required Americans to obtain commercial insurance. Two other judges, though, have held the law to be constitutional, meaning the conflicting opinions will begin winding their way to the U.S. Supreme Court for a final determination.

The insurance mandate doesn't take effect until 2014, but as the New York Times noted in a recent article, many new regulations already are operating, such as requirements that insurers cover children with pre-existing health conditions and eliminate lifetime caps on benefits. States also are preparing for the major expansion of Medicaid eligibility and the introduction of health insurance exchanges in 2014.

The health reform law expands Medicaid's income eligibility level for non-elderly adults up to 133 percent of the federal poverty line—up to about $30,000 for a family of four—across the nation in 2014.

The recently published study, authored by researchers at the George Washington University School of Public Health and Health Services, explains that coverage will expand substantially in those states with restrictive Medicaid eligibility requirements and high uninsurance rates. However, since many of those states have limited primary-care capacity, the researchers say, this will create a gap between the demand for medical care by those who are newly insured and the current supply of physicians and staff in each state.

Using estimates of the size of planned Medicaid expansions and current primary-care capacity, the researchers computed rankings across the 50 states and the District of Columbia. The authors found that many of the states that would experience the largest Medicaid expansions under the ACA unfortunately also have the weakest primary-care capacity.

"For many years, we've been aware that there is a maldistribution of primary-care practitioners across the nation; national health reform really moves this issue to the forefront," says Dr. Lynn Goldman, dean of the School of Public Health and Health Services.

"Federal and state officials will need to collaborate with physicians and other clinicians to bolster primary-care capacity when the insurance expansions begin just three years from now," says Dr. Leighton Ku, professor of health policy at George Washington and lead author of the paper. "The challenges are greater in southern and Midwestern states, because insurance coverage will grow more in those states, but they have fewer practitioners ready to provide care."

Eight states—Oklahoma, Georgia, Texas, Louisiana, Arkansas, Nevada, North Carolina, and Kentucky—were found to have especially weak primary-care infrastructure in the face of large Medicaid expansions and 17 other states—Idaho and Oregon among them—also could face substantial challenges, the researchers concluded. The interstate differences underscore the importance of state-specific and local plans to address the capacity and access issues.

Washington was among eight states found to have the greatest primary-care capacity relative to the size of their Medicaid expansions. Others in that group included Massachusetts, Vermont, the District of Columbia, Maine, New York, Rhode Island, and Connecticut.

"Community health centers play a key role in addressing the nation's primary care needs," says Julio Bellber, president and CEO of the RCHN Community Health Foundation, which helped sponsor this study,

"It is fortunate that health reform makes a major new investment in health centers, which are poised to expand substantially to improve access in underserved communities."