Association for Public Policy Analysis & Management

One Affordable Care Act provision mandated that Medicaid payment rates equal Medicare for many primary care services provided by primary care physicians in 2013 and 2014.  This led to a 50% increase in Medicaid-to-Medicare fee ratios across states, with some experiencing substantially larger increases.  This fee bump was expected to be important since prior to 2013, fewer physicians accepted Medicaid compared to patients with other payers.  In addition, past research has found a positive cross-sectional correlation between state Medicaid fee levels and patient access measures such as self-reported information on whether patients had trouble finding a physician to see them or whether they had had at least one physician visit in the past year.   This study is the first to use nationally-representative data to assess the effect of the 2013-2014 Medicaid fee bump on physician participation in Medicaid and patient access measures.

 Multivariable analyses predicted primary care physicians’ acceptance of new Medicaid patients as a function of time and the Medicaid fee bump, controlling for physician and state-level characteristics.   Physicians outside of primary care served as a control group.   The independent variable of interest was an interaction between a variable identifying the post-fee-bump-period and a continuous variable measuring the magnitude of the fee bump by state.  Several self-reported patient access measures for Medicaid patients were modeled similarly, using patients with private insurance as control group.  Models were estimated with linear probability models using sample weights.  Standard errors were clustered by state.  Data on acceptance of Medicaid patients among primary care (general/family practice, internal medicine and pediatrics) physicians came from the the 2011-2014 National Electronic Health Records Survey (NEHRS), a supplement to the National Ambulatory Medicare Care Survey conducted by the National Center for Health Statistics.      Patient access measures were analyzed using a restricted-use version of the 2011-2014 National Health Interview Survey (NHIS).

 No overall increase in acceptance of new Medicaid patients was found for primary care or other physicians in the NEHRS during the sample period.  For example, about 65% of primary care physicians accepted new Medicaid patients in 2013 compared to 67% in 2014, though this difference was not statistically significant and did not differ significantly by the magnitude of the Medicaid fee bump by state.  No significant changes were found for other measures of participation in Medicaid among primary care physicians, such as the probability that a physician had at least one Medicaid patient or the percent of Medicaid patients in his or her practice.   Using the NHIS data, the study did not find a significant correlation between the Medicaid fee bump and patient access measures in 2013-2014 relative to 2011-2012. 

Although sample sizes were smaller in the NEHRS than in some other analyses using non nationally-representative data, the sample size in the NEHRS appears sufficient to rule out all but very small effects of the sizeable changes in fee ratios.  Although future analysis is likely to be fruitful, it is possible that the temporary nature of the fee increase limited physician response.