Morgan 2019: overdose risk on naltrexone vs buprenorphine in insurance data

What they tested

Researchers followed commercially insured people in the United States who were diagnosed with opioid use disorder and started medication between 2010 and 2016. They compared the risk of an opioid-related overdose, identified from diagnosis codes, during time on each medicine with time off treatment.

They also checked whether overdose risk rose in the four weeks after people stopped a medicine.

What they found

1,386 people were prescribed the extended-release naltrexone shot (a median of 9 months of filled prescriptions), 7,782 oral naltrexone (5 months) and 40,441 buprenorphine (19 months) at least once.

Buprenorphine was linked to a significantly lower risk of opioid overdose (HR 0.40, 95% CI 0.35-0.46). For the naltrexone shot (HR 0.74, 95% CI 0.42-1.31) and oral naltrexone (HR 0.93, 95% CI 0.71-1.22), no significant link was found.

There was no link between overdose and the four weeks after stopping any of the medicines.

Limits

• People weren't randomly assigned to medicines, so the results show links, not cause and effect.
• Far fewer people were on the naltrexone shot (1,386) than on buprenorphine, so its estimate was much less precise.
• Only commercially insured people were included, and overdoses were identified from billing diagnosis codes.

What it means if you're considering naltrexone

In real-world insurance data, only buprenorphine was clearly linked to fewer overdoses during treatment. The result for the naltrexone shot pointed toward fewer overdoses but was too uncertain to call either way, so the study doesn't prove the shot fails to protect. The authors call for more research on the benefits and risks of each option.