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

Abstract

<b><i>Background:</i></b> 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. <b><i>Objectives:</i></b> We aimed to test the relationship between baseline preference for XR-NTX and adherence to treatment, use of illicit opioids, and risk of relapse. <b><i>Methods:</i></b> 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. <b><i>Results:</i></b> 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 (<i>p</i> &#x3c; 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, <i>p</i> = 0.013). Opioid use was significantly higher among participants who switched to XR-NTX with the lowest preference than the medium (<i>p</i> = 0.003) or the highest (<i>p</i> = 0.001) preference. The risk of relapse to opioids, however, was significantly higher among XR-NTX continuing participants with the lowest (<i>p</i> = 0.002) or the medium (<i>p</i> = 0.043) preference than those with the highest preference. <b><i>Conclusions:</i></b> 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.