Client factors associated with length of stay in methadone treatment among heroin users who inject drugs: quantitative analysis of state-level substance abuse treatment utilization data.

The objective of this study was to examine, for a population of 8,258 adult injection drug users (IDUs) who all had entered a Massachusetts licensed methadone maintenance treatment program (MMT) between 1996 and 2002, client factors associated with remaining in MMT for a minimum of 1 year after program entry. Two binomial logistic regression models were developed. The first model examined the association between age, sex, race/ethnicity, parental status, employment status, educational status, health insurance status, homelessness status, having injected drugs in the past month, residential treatment use, number of overall treatment admissions, and whether a client's longest consecutive stay in MMT had lasted for 1 year or more. Second, to examine the stability of the statistical relationships identified in the first logistic regression model, a second logistic regression model examined whether there were significant differences in client level characteristics between those who used MMT for 6 months or less compared with their counterparts. Those who were older, women, those who were not homeless, those who resided with their children, those who had public health insurance, and those who had not used residential treatment were significantly more likely to have stayed in MMT for at least 1 year or more. In contrast, those who were younger, males, homeless, did not live with children, had no insurance, and had used residential treatment were significantly more likely to have stayed in MMT for 6 months or less compared with their counterparts. Those who stayed in MMT for 1 year or more were more likely to have stable lives compared with those who dropped out of MMT before a year. Providing services to improve MMT clients' employment, housing, and family stability may help improve MMT retention rates. Second, clients with a history of having used residential substance abuse treatment were more likely to stay in MMT for a shorter time period compared with their counterparts. The extent to which treatment bifurcation is a matter of choice or related to other factors needs to be further explored.