Without insurance, half of the patients would pay at least $250 to start taking buprenorphine. And 19 providers, or 5 percent, said the cost would be at least twice that high. Half of the clinicians who discussed pricing also said there could be additional fees for urine drug testing or other lab work before patients could start taking buprenorphine.

The study wasn’t a controlled experiment designed to prove whether or how appointment availability or treatment timing might directly impact outcomes for patients seeking buprenorphine.

One limitation of the study is that it excluded most U.S. states, researchers note in the Annals of Internal Medicine. Another drawback is that the states that were included all expanded Medicaid eligibility under Obamacare, which might impact both access and affordability of buprenorphine treatment, but the study couldn’t account for that.

It’s also not clear from the study why it’s harder to get seen with Medicaid, said Dr. Pooja Lagisetty of the University of Michigan in Ann Arbor, an author of an accompanying editorial.

Doctors might not accept Medicaid because of legal or “red tape” concerns like excessive paperwork, or because of low reimbursement rates, or some combinations of these issues, Dr. Lagisetty said by email.

“Willing clinicians are often available for same-day or appointments within a week, demonstrating that they do have availability, and many said yes and had short wait times,” Dr. Lagisetty said.

“However, there was a very large proportion of clinicians who couldn’t even be reached,” Dr. Lagisetty added. “It is unclear whether these clinicians are saying no because they are at capacity versus they are just not providing treatment at all—I suspect many may fall into the latter category.”