Methadone treatment and HIV and hepatitis B and C risk reduction among injectors in the Seattle area.

Drug treatment has the potential to reduce incidence of blood-borne infections by helping injection drug users (IDUs) achieve abstinence or by decreasing the frequency of injection and sharing practices. We studied the associations between retention in methadone treatment and drug use behaviors and incidence of hepatitis B and C in a cohort of IDUs in the Seattle, Washington, area. Data on IDUs entering methadone treatment at four centers in King County, Washington, were collected through face-to-face interviews using a standardized questionnaire at baseline and 12-month follow-up between October 1994 and January 1998. Blood specimens were obtained and tested for human immunodeficiency virus (HIV) and hepatitis B and C. Drug treatment status at follow-up was analyzed in relation to study enrollment characteristics and potential treatment outcomes, including injection risk behaviors, cessation or reduced frequency of injection, and incidence of hepatitis B and C. Of 716 IDUs, 292 (41%) left treatment, 198 (28%) disrupted (left and returned) treatment, and 226 (32%) continued treatment throughout the 1-year follow-up period. Compared to those who left treatment, subjects who disrupted or continued were less likely to inject at follow-up (odds ratio [OR] = 0.5, 95% CI 0.3-0.7; and OR = 0.1, 95% CI 0.1-0.2, respectively). Among the 468 (65%) subjects who continued injecting, those who continued treatment injected less frequently, were less likely to pool money to buy drugs (OR = 0.5, 95% CI 0.3-0.8) and inject with used needles (OR = 0.5, 95% CI 0.2-0.8) compared to those who left treatment. Cooker or cotton sharing was not associated with retention in treatment, but hepatitis B incidence was lowest among those who continued treatment. The results of this study suggest drug use risk reduction is more likely to be achieved by those who remain in drug treatment and by those who stop injecting, but that those who drop out and return and those who continue to inject while in treatment may also benefit. This supports the role of consistent drug treatment in an overall harm-reduction strategy.