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.

Chronic Pain Among Patients With an Opioid Use Disorder.

BACKGROUND AND OBJECTIVES: Chronic pain is not well understood in opioid-dependent populations. We report the prevalence of chronic pain and pain characteristics in an opioid-dependent population by treatment type and gender. METHODS: This cross-sectional study opportunistically recruited 569 patients (32% women) receiving treatment for opioid use disorder (DSM-5) in Norway during 2016-2018 (83% received opioid maintenance treatment, 17% received treatment without medication). We asked about chronic pain (≥3 months; ICD-11), pain severity (NRS-11), and other pain characteristics. RESULTS: Overall, 55% reported chronic pain (≥3 months), with a higher prevalence among women (61% vs 52%, P = .041) and patients receiving methadone (66%) compared with buprenorphine or no medication (46% and 45%, P < .001). Chronic pain was associated with higher age (P < .001) and higher doses of methadone (P = .048). The average duration of pain was 11 years. The most frequently reported pain locations were the lower extremities (59%) and the back (54%), and 69% reported more than one pain location. Constant pain and migrating pain were significantly associated with both moderate (adjusted odds ratio [aOR]: 2.04, confidence interval [CI]: 1.12-3.74 and aOR: 2.44, CI: 1.09-5.43) and severe pain intensity (aOR: 2.08, CI: 1.14-3.80 and aOR: 2.46, CI: 1.10-5.47). Reporting no effect of analgesics was associated with severe pain intensity (aOR: 0.54, CI: 0.29-0.99). CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: Over half reported chronic pain, and rates were highest among women and patients receiving methadone. New contributions to the field are descriptions of pain characteristics by gender and pain severity, and interactions between medication type and age. (© 2021 The Authors. The American Journal on Addictions published by Wiley Periodicals LLC on behalf of The American Academy of Addiction Psychiatry). (Am J Addict 2021;00:00-00).

No increased pain among opioid-dependent individuals treated with extended-release naltrexone or buprenorphine-naloxone: A 3-month randomized study and 9-month open-treatment follow-up study.

BACKGROUND AND OBJECTIVES: It is presently unclear whether extended-release naltrexone hydrochloride treatment induces pain or aggravates existing pain among individuals with opioid use disorders. We assessed changes in pain among individuals receiving treatment with either extended-release naltrexone hydrochloride or buprenorphine-naloxone hydrochloride. METHODS: This randomized prospective open-label clinical study included 143 participants (aged 18-60 years) with opioid dependencies, recruited from outpatient addiction clinics at five urban hospitals in Norway. After in-patient detoxification from opioids, patients were randomized to 12-week treatment with either long-acting naltrexone (380 mg intramuscularly injected every four weeks) or buprenorphine-naloxone (flexible 4-16 mg sublingual doses daily). This phase was followed by a 9-month open-treatment study with the participant's choice of either naltrexone or buprenorphine-naloxone. Changes in pain were assessed every 4 weeks using the Norwegian Short-Form of McGill Pain Questionnaire. RESULTS: Throughout the study period, we found no increase in mean sensory pain, affective pain, or present pain intensity on the McGill Pain Questionnaire, in either treatment group, including the subgroups of participants with chronic pain. Participants who switched from buprenorphine-naloxone to extended-release naltrexone treatment after week 12 reported no increase in pain intensity during longer-term treatment. Women experienced significantly more affective pain symptoms than men (p = .01). DISCUSSION AND CONCLUSIONS: Among individuals with opioid use disorder, switching from daily opioid use to long-acting naltrexone did not induce pain, or aggravate mild-to-moderate chronic pain. SCIENTIFIC SIGNIFICANCE: In opioid-dependent individuals, mild-to-moderate chronic pain was not influenced by opioid agonist or antagonist treatment. TRIAL REGISTRATION: Clinicaltrials.gov #NCT01717963, first registered: Oct 28, 2012. Protocol version # 3C, June 12th 2012. (Am J Addict 2018;XX:1-9).