Background: There are few descriptions of patterns of long-term participation in methadone treatment. There has been progressive expansion of methadone maintenance treatment (MMT) in Australia in the last 15 years, and by international standards Australia has a high participation rate in MMT, and has accumulated extensive data on participation.
Aim: (1) To analyse predictors of retention in treatment (a proxy measure of treatment effectiveness) in three cohorts of people entering public and private methadone treatment, in 1990, 1995, and 2000 in the state of New South Wales (NSW), and to compare retention rates with those reported from recent clinical trials; and (2) to describe the pattern of participation in subsequent treatment and predictors of re-entry.
Method: Sequential first admissions to MMT for the month of February during 1990, 1995, and 2000, were identified from the NSW Health database. Initial treatment setting (public or private) was identified. Pattern of subsequent participation in treatment of all subjects was also extracted. Descriptive statistics were generated, and predictors of retention in treatment and re-entry to treatment were analysed.
Results: The sample comprised 342 subjects commencing in private and 135 in public settings. Retention did not differ between settings. At 6 months, 51% in the current study were retained, compared to 48% in pooled clinical trials from Australia. There was a significant cohort effect; at 3 months retention was significantly better in the 1990 cohort, but by 12 months, differences between the year-cohorts were not statistically significant. Most people who left treatment dropped out; two-thirds subsequently re-entered MMT, often having multiple episodes. Participation in non-continuous treatment was around 45% for the 5 years after first entering treatment. Using multiple logistic regression, the significant predictors of re-entry to treatment were age, and duration of first treatment episode; specifically, older people and those with >12 months continuous treatment were significantly less likely to re-enter.
Conclusion: Retention in treatment in practice, across a range of settings, appears comparable to treatment delivered in clinical trials. Participants cycle in and out of treatment, and this recycling appears to have increased as the program has expanded and access to treatment has increased.