Methamphetamine dependence: a closer look at treatment response and clinical characteristics associated with route of administration in outpatient treatment.

Relatively little is known about the clinical treatment response characteristics associated with route of methamphetamine (MA) administration. We examined sociodemographic, drug use, treatment response, as well as psychiatric and medical characteristics associated with route of administration among 974 methamphetamine abusers in outpatient treatment during 1999-2001. Injectors had the poorest treatment prognosis: poorer treatment engagement, greater drug use during treatment, lower treatment completion rates, and more MA use at 12 months post-admission than did smokers and intranasal users. On many treatment response measures, MA smokers were almost as severely impaired as injectors, and in general, intranasal users were least impaired. Psychological and medical impairment, before and after treatment, was also highest among injectors. This study contributes new insights about clinical treatment response and outcomes associated with route of administration among MA-dependent users.