The Predictive Value of Degree of Preference for Extended-Release Naltrexone for Treatment Adherence, Opioid Use, and Relapse.

BACKGROUND

Extended-release naltrexone (XR-NTX) is effective for illicit opioid abstinence as an opioid maintenance treatment. To improve treatment outcomes, patient's preference for the modality of treatment is an important factor.

OBJECTIVES

We aimed to test the relationship between baseline preference for XR-NTX and adherence to treatment, use of illicit opioids, and risk of relapse.

METHODS

In an open-label, Norwegian clinical trial participants with opioid use disorder were randomized to either monthly injections with XR-NTX or daily sublingual buprenorphine-naloxone (BP-NLX) for 12 weeks. Subsequently, participants could continue with their preferred medication in a 36-week follow-up and in a prolonged period of 104 weeks.

RESULTS

Of 153 participants who completed detoxification, 72% were men, with a mean age of 36 years. Preference levels were similar across the randomized groups, with no significant associations between preference and adherence to treatment, opioid use, or relapse. The BP-NLX group had a significantly higher risk of first relapse to opioids than the XR-NTX group for all levels of preference (p < 0.001) and a significantly higher number of days of illicit opioid use. In the follow-up period, the adherence rate was twice as high among participants with the highest preference compared to participants with the lowest preference, both among those who switched to XR-NTX and those who continued (hazard ratio 2.2; 1.2-4.0, p = 0.013). Opioid use was significantly higher among participants who switched to XR-NTX with the lowest preference than the medium (p = 0.003) or the highest (p = 0.001) preference. The risk of relapse to opioids, however, was significantly higher among XR-NTX continuing participants with the lowest (p = 0.002) or the medium (p = 0.043) preference than those with the highest preference.

CONCLUSIONS

Individuals who matched with their preferred treatment used less illicit opioids than those who did not during short-term treatment. However, baseline preference for XR-NTX treatment primarily influenced longer term opioid use and treatment adherence.