The Affordable Care Act (ACA) did change physicians' total patient mix by health insurance status, with the percentage of uninsured patients shrinking and the average Medicaid patient load increasing in states that expanded eligibility.

While supporters of bills to repeal and replace the ACA, like House Speaker Paul Ryan, have argued more doctors won’t see Medicaid patients after the ACA expansion because of low reimbursement rates, a survey from the American Medical Association said otherwise, with 82.6 percent of physicians nationwide reporting having treated Medicaid patients in 2016, a slight increase from 81.9 percent in 2012.

In the 31 states and the District of Columbia that had expanded Medicaid eligibility, the share of physicians seeing Medicaid patients didn’t change much from 2012 to 2016 (82.4 percent vs. 82.6 percent). Instead, the data suggested physicians already participating in Medicaid took on more patients, with the average Medicaid patient share for each physician increasing from 16.2 percent in 2012 to 17.6 percent in 2016.

Additionally, the average uninsured patient share decreased from 6.4 percent to 5.4 percent in expansion states.

Nonexpansion states didn’t see the same gains, with “essentially no change” in Medicaid patient load and a statistically insignificant decrease in the uninsured patient load.

“The most striking difference was in the percentage of physicians with uninsured patients,” the report said. “While this fell by more than 7 percentage points in expansion states, the drop in non-expansion states was only 2.2 percentage points.”

Nearly all (98 percent) reported treating privately insured patients in 2016, while 89 percent accepted Medicare beneficiaries. More than two-thirds of the doctors who reported not seeing Medicare patients were pediatricians. Fewer physicians had patients that were uninsured in 2016 (75.6 percent) compared to 2012 (81.3 percent), and the average uninsured patient load declined (from 6.9 percent of their patients in 2012 to 6.1 percent in 2016).

The average patient mix still favored commercially insured (43.4 percent), followed by Medicare (29.3 percent) and Medicaid (16.9 percent). More than half of physicians said Medicaid accounted for 10 percent or less of their patient load, while 48 percent said the commercially insured made up 40 percent or more of their patients.

Patient mix varied by specialty, though all had “substantial involvement” with Medicaid patients. Emergency medicine, radiology and anesthesiology all had more than 90 percent of physicians reporting they treated Medicaid patients in 2016. The largest average Medicaid patient share for Medicaid was found in pediatrics at 34.7 percent, more than double any other specialty.

“Expanding Medicaid has provided much needed coverage to our low-income patients, improved access to care, and enhanced the health and well-being of the newly insured,” said AMA President David Barbe in a statement. “Medicaid expansion is not simply a budget issue. Lawmakers must also consider the real human effects of this decision, including the health and well-being of those who have gained coverage under expansion.”

Emergency physicians had by far the largest average uninsured patient share at 14.2 percent, with the other specialties ranging from 4.3 to 8.1 percent. Emergency medicine also had the smallest commercially insured patient share at 29 percent, with the highest share found in obstetrics/gynecology at 57 percent. For Medicare, the patient share ranged from 5.2 percent for pediatrics, 14 percent for obstetrics/gynecology and 19.2 percent for psychiatry to more than 40 percent for medical and surgical specialties.