Hospital psychiatric comorbidity and its role in heroin dependence treatment outcomes using naltrexone implant or methadone maintenance

Abstract

Our objectives were to (i) estimate lifetime prevalence of psychiatric comorbidity in heroin users and (ii) evaluate psychiatric comorbidity as a predictor of drug-related hospitalization following either (a) methadone maintenance or (b) naltrexone implant treatment. Our method consisted of retrospective, longitudinal follow-up using prospectively collected, state-wide hospital data on two cohorts of heroin-dependent persons (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition), first time treated with naltrexone implant (n = 317) or methadone (n = 521) between January 2001 and December 2002. Outcome measures were: (i) prevalence of comorbidity and (ii) changes in risk for drug-related hospitalization - categorized as 'opioid drugs', 'non-opioid drugs', and 'any drug' - to 3.5 years post-treatment. Nearly 32% had psychiatric comorbidity. In both cohorts, comorbid patients generally had significantly greater odds of drug-related hospitalization pre-treatment compared with non-comorbid counterparts. These differences generally reduced in magnitude post-treatment. Comorbid naltrexone-treated patients had less 'opioid' and 'any drug' related hospitalizations post-treatment. Similarly, comorbid methadone-treated patients had reduced hospitalization risk for 'non-opioid' and 'any drug' related hospitalization post-treatment. Treatment of persons without depression, anxiety, or personality disorder with naltrexone implant was associated with increased risk of 'non-opioid' drug-related hospitalization, while methadone treatment was associated with increased risk of 'opioid' drug-related hospitalization. Although comorbid heroin users entered treatment with significantly higher risk of drug-related hospitalization than non-comorbid users, substantial reductions in drug-related hospitalization were generally observed post-treatment. This challenges the view that comorbidity predicts poor drug treatment outcomes. Differences in research methodology were noted; recommendation for rigorous analytical methodology in future research on assessing treatment outcomes was accordingly offered.