Nonstructured treatment interruptions among injection drug users in Baltimore, MD

Background: We characterized patterns of highly active antiretroviral therapy (HAART) use and predictors of nonstructured treatment interruptions (NTIs) among injection drug users (IDUs) in Baltimore, MD. Methods: Three hundred thirty-five IDUs who initiated HAART from 1996 to 2006 were studied. NTIs were defined as any subsequent 6-month interval where HAART was not reported. Predictors of the first NTI and subsequent restart of HAART were examined using Cox regression. Results: Two hundred sixty (78%) reported ≥1 NTI. Of 215 with ≥1 follow-up visit after the NTI, 44 (20%) never restarted HAART, 62 (29%) restarted and remained on HAART, and 109 (51 %) reported multiple NTIs. NTIs were less likely among those who initiated HAART in later calendar years and had a recent outpatient visit and more likely among women, persons with detectable HIV RNA at the prior visit, and those who reported injecting daily. Among those with NTIs, interuptions occurred earlier in persons who were younger, who did not have a prior AIDS diagnosis, and who were actively injecting; NTIs lasted longer in persons who had higher HIV RNA levels, in persons who were incarcerated, and in persons drinking alcohol. A recent outpatient visit and not actively injecting were associated with restarting HAART Conclusions: NTIs were common in this population and occurred most frequently in the setting of active drug use and disruption of health care. Effective linkages between primary care for HIV and substance abuse treatment may improve HAART outcomes in this population.