Veteran adherence to oral versus injectable AUD medication treatment.

Introduction: AUD medication treatment has been shown to improve outcomes compared with placebo when confined to per-protocol analysis. The same outcomes, however, have not always been maintained in intent-to-treat analysis, thus suggesting adherence may have a significant impact on efficacy outcomes. There is conflicting evidence present in the literature comparing adherence to oral versus injectable AUD pharmacotherapy and a paucity of information in the veteran population on risk factors for low adherence.

Methods: The primary end point of this retrospective chart review was to determine whether adherence rates differ between oral and injectable AUD treatments in veterans during the first year of treatment (at 3, 6, 9, and 12 months) using the portion of days covered model. Secondary end points were to determine differing characteristics between patients with high versus low adherence and compare alcohol-related readmission rates and discontinuation rates between groups.

Results: Adherence to injectable extended-release (XR) naltrexone was significantly higher than oral naltrexone at all time points and was significantly higher than disulfiram at 3, 6, and 9 months, but it was not significantly different from acamprosate at any time point. At months 9 and 12, acamprosate had significantly higher adherence compared with oral naltrexone. Patients with higher adherence were seen more frequently in the mental health clinic and had previously tried more AUD medications. The discontinuation rates and alcohol-related admission rates were not significantly different between groups at 1 year.

Discussion: XR naltrexone may improve adherence rates compared with oral naltrexone or disulfiram, but not acamprosate based on these outcomes. Patients may have increased adherence if they are seen more often in clinic and have trialed more AUD medications.