Extended-release naltrexone for alcohol and opioid problems in Missouri parolees and probationers
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Extended-release naltrexone for alcohol and opioid problems in Missouri parolees and probationers.

Crits-Christoph P, Lundy C., Stringer M. et al
Journal of Substance Abuse Treatment: 2015, 56, p. 54–60.
Unable to obtain a copy by clicking title? Try asking the author for a reprint by adapting this prepared e-mail or by writing to Dr Crits-Christoph at crits@mail.med.upenn.edu.

Long-acting injectable naltrexone blocks the effects of opiates for about a month and has also helped dependent drinkers cut back. Treatment records in the US state of Missouri showed that among the few problem substance using offenders allocated to or who chose this treatment, a much higher proportion became abstinent than those offered other kinds of addiction treatment.

Summary This account is taken largely from the authors’ discussion of the meaning and significance of their findings. The study was based on routinely collected records of how patients with alcohol and/or opioid use problems progressed when allocated to or agreeing to different substance use treatments while under the supervision of the criminal justice system in the US state of Missouri.

About 80% of the patients had been referred to treatment by probation or parole officers, courts or other criminal justice authorities. Treatment providers typically determined the treatment plan though in the case of participants tried in specialist drug courts, the court team, which includes a treatment professional, determined the plan. Patients could choose or reject pharmacological treatments, which were combined with psychosocial therapies. During the year of the study, only one patient received acamprosate and none disulfiram, so the analysis was confined to the 2513 offered psychosocial treatments like counselling but prescribed no medications, the 168 prescribed buprenorphine combined with naloxone [mainly used to substitute for illegal opiate-type drugs], the 45 prescribed oral naltrexone, an opiate-blocking drug, and the 156 prescribed the long-acting injectable form of naltrexone.

Among the three-quarters of patients who during the year of the study were discharged from treatment, on leaving their first treatment episode in the year patients treated with long-acting naltrexone were more likely to have been recorded as having become abstinent from alcohol and other drugs (an increase from 16% at treatment entry to 67% at discharge) than those treated with oral naltrexone, buprenorphine, or psychosocial treatment only. They were also significantly more likely to have stayed longer in treatment than those treated with oral naltrexone or psychosocial treatment only. These findings remained after adjusting for known and unknown differences between the patients who received different treatments, and when the analysis was confined to problem users of opiate-type drugs like heroin.

This study documents real-world clinical experience with long-acting naltrexone, but the results are consistent with those from controlled clinical trials. The difference in improvement in rates of abstinence between long-acting naltrexone and the other treatments was clinically meaningful – over three times that for psychosocial treatment only, over four times that for oral naltrexone, and over 10 times that for buprenorphine/naloxone. The finding that patients treated with long-acting naltrexone remained in care longer than those treated with oral naltrexone was also clinically meaningful; the typical duration of care was 61% longer.

These data provide support for the rationale behind long-acting naltrexone – to address the fact that many patients do not take oral naltrexone as intended. There was however no evidence that long-acting naltrexone was associated with fewer arrests or more patients gaining employment compared to oral naltrexone, buprenorphine or psychosocial treatment only. It is likely that such changes need to be studied over longer periods and longer durations of treatment; all the data from this analysis were drawn from a one-year period (during which treatment could be started at any time), and the average duration of an episode of care was 33 to 82 days.

Findings logo commentary As the authors acknowledge, this was not a random allocation study but based on routinely collected records. It is highly likely that despite attempts to adjust for differences between patients, those selected for and who accepted the different treatments had different characteristics and motivations which complicate using the results to compare the effectiveness of the treatments. The study focused on the comparison between how patients who were injected with long-acting naltrexone fared compared to other patients. The preparation blocks the effects of opiate-type drugs for about a month, and in this sample it was mainly used to treat opiate addiction. The relatively few patients who were offered and accepted this treatment were presumably those prepared to commit to a month without being able to experience opiate-type effects (the preparation is also used to treat dependent drinking, and seems to have been used for this purpose among a minority of the patients prescribed it in the featured study). To account for such differences between patients allocated to the treatments, the analysts used advanced methods capable of adjusting the results for unmeasured (eg, in motivation) as well as known differences, and still long-acting naltrexone remained statistically superior to the other treatments, offering some reassurance that the results reflected the effectiveness of the treatments in promoting abstinence at the point of discharge from the first treatment episode in the year of the study. Whether long-acting naltrexone’s advantage remained after treatment ended is not reported.

For more on long-acting naltrexone see this Effectiveness Bank hot topic.

Thanks for their comments on this entry to research author Paul Crits-Christoph of the University of Pennsylvania in the USA. Commentators bear no responsibility for the text including the interpretations and any remaining errors.

Last revised 14 August 2015. First uploaded 14 August 2015

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