Many people struggling with opioid addiction can't find a doctor to provide medication-assisted treatment, even though it's highly effective. One reason could be that doctors who are qualified to prescribe the medication typically treat just a handful of patients.

Researchers at the RAND Corporation looked at pharmacy records from the seven states with the most doctors approved to prescribe buprenorphine, which helps people manage cravings and avoid withdrawal. They found 3,234 doctors who had prescribed the drug, also known as Suboxone, to new patients from 2010 to 2013. The median number of patients by a doctor treated each month was 13. About half of the doctors treated 4 to 30 patients; 22 percent treated less than 4; 20 percent treated 31 to 75.

"We were really surprised," says Dr. Bradley Stein, a psychiatrist and lead author of the study, which was published Tuesday in JAMA, the journal of the American Medical Association. "We found that only about 10 percent of doctors were what we would call heavy prescribers, with more than 75 patients a month."

Only a fraction of the 4 million people thought to abuse prescription painkillers or heroin in the U.S. are getting medication-assisted treatment.

There's been a big push to make it easier for doctors to prescribe buprenorphine, including new rules announced by the Obama administration in July that raised the number of patients a doctor can treat from 100 to 275. But this data suggests that those limits aren't the only barrier to getting treatment to more people.

The researchers also were surprised to find that most patients weren't prescribed buprenorphine for very long, even though it can be used long term. The mean length of prescribing was 53 days per patient.

"This really brought home for us the need for multiple approaches, so doctors are willing and able to prescribe buprenorphine," Stein says.

Urban areas have typically been better equipped to provide treatment for opioid addiction, whether with methadone clinics or with buprenorphine, which people can take at home and doesn't require people a daily clinic visit. But many people struggling with opioid addiction live in smaller cities or rural areas where physicians have little experience with treating addiction to heroin and prescription opioids.

That includes towns like Bridgton, Maine, where family physicians shied away from treating addicts until they realized that their own patients were the ones overdosing and dying.

Just taking an online course on how to prescribe buprenorphine won't be enough for many providers, Stein says, especially since many patients with opioid addiction also have other problems that need care. "We really need to think about providing mentorship, providing consultation, providing clinical support," Stein says.

Medication-assisted treatment is supposed to include counseling, and that can be hard to find, especially in rural areas. "So we may need to think about telehealth or online counseling," Stein says. "We may need to be creative to have people receive effective treatment, no matter where they live."

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