Completion of isoniazid preventive therapy and survival in HIV-infected, TST-positive adults in Tanzania

Abstract

SETTING: The World Health Organization recommends the use of isoniazid preventive therapy (IPT) for human immunodeficiency virus (HIV) infected patients with a positive tuberculin skin test (TST). However, due to concerns about the effectiveness of IPT in community health care settings and the development of drug resistance, these recommendations have not been widely implemented in countries where tuberculosis (TB) and HIV co-infection is common. OBJECTIVE: To evaluate the effectiveness of IPT on survival and TB incidence among HIV-infected patients in Tanzania. DESIGN: A cohort study nested within a randomized trial of HIV-infected adults with baseline CD4 counts of ≥ 200 cells/μ l was conducted to compare survival and incidence of active TB between TST-positive subjects who did or did not complete 6 months of IPT in the period 2001-2008. RESULTS: Of 558 TST-positive subjects in the analytic cohort, 488 completed 6 months of IPT and 70 did not. Completers had a decrease in mortality compared to non-completers (HR 0.4, 95%CI 0.2-0.8). However, the protective effect of IPT on the incidence of active TB was non-significant (HR 0.6, 95%CI 0.3-1.3). CONCLUSION: Completion of IPT is associated with increased survival in HIV-infected adults with CD4 counts ≥ 200 cells/μ l and a positive TST.