HIV infection and sputum-culture conversion in patients diagnosed with Mycobacterium tuberculosis:: A population-based study

Objectives: To estimate the effect of, human immunodeficiency virus infection on treatment outcome of anti-tuberculosis therapy at the population level. Materials and methods: A retrospective cohort study based on data collected through the expanded program on tuberculosis surveillance on all reported and verified cases of tuberculosis in the State of North Carolina from 1993 to 1998. Eligible patients were sputum-positive at baseline, with known and documented HIV-serology status. We analyzed 1030 cases consisting of 210 HIV-positive and 820 HIV-negative tuberculosis patients. Patients were followed up for 12 months to document sputum conversion. Results: Among HIV-infected individuals, 60% (126) converted compared to 75% (615) of HIV-uninfected persons. Using the Cox Proportional Hazard method to estimate the likelihood of conversion, we found the difference in conversion rates to be highly significant (crude hazard ratio = 0.54, CI = 0.45-0.66). The inverse relationship between HIV-seropositivity and sputum conversion still persisted and remained practically unchanged after adding potential confounding factors into the model (adjusted hazard ratio = 0.56, 95% CI = 0.46-0.69). Conclusion: Response to anti-tuberculosis therapy was significantly less favorable in HIV-infected than in HIV-uninfected tuberculosis patients. The importance of, longer and closer monitoring of tuberculosis treatment in HIV-positive patients is highlighted.