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Isoniazid Prophylaxis in HIV-Infected Patients

HIV-infected patients who received isoniazid preventive therapy as part of a clinical trial in Botswana had low rates of incident tuberculosis and severe adverse events; adherence was quite high.

The WHO currently recommends a 6-month course of isoniazid preventive therapy (IPT) for all HIV-infected patients living in areas with a high prevalence of tuberculosis (TB). However, the uptake, efficacy, and safety of this approach have not been widely studied, and the implementation of IPT programs has lagged. In this report, investigators describe recruitment and initial outcomes from an IPT trial in Botswana, in which HIV-infected patients received open-label isoniazid (plus pyridoxine) for 6 months. The patients were then were randomized to isoniazid or placebo for 30 months, but the results of that intervention have not yet been reported.

Of the 4331 HIV-infected adults who were referred for screening for the trial, only 1995 (46%) were actually enrolled. The primary reasons for exclusion were current illness, an abnormal chest x-ray, and a neutrophil count <1000 cells/mm³ (the latter two were exclusion criteria for the clinical trial but were not among the screening criteria used in the Botswana National IPT Program).

During the first 6 months of the study, when all patients received IPT, only 8 (0.4%) were diagnosed with TB, and 28 (1.4%) experienced severe adverse events (most often hepatitis). Overall, 21 patients (1%) died, including 1 patient who died of hepatic encephalopathy that was likely isoniazid-related. Adherence rates were high: 86% of patients visited the clinic monthly for isoniazid refills, and 91% of the patients with pill-count data available took at least 80% of their pills. Adherence was better among the 23% of patients who initiated antiretroviral therapy (ART) while receiving IPT than among those who did not.

Comment: Rates of incident TB and severe toxicity were low in this population of HIV-infected adults, all of whom received 6 months of IPT and had good access to ART. These findings are not entirely generalizable to a program setting, given that most IPT programs do not screen patients with chest x-rays and safety labs, as was done here, and that less than half the patients screened for the trial were actually enrolled. Furthermore, study participants were likely to be more motivated and to receive more-intensive adherence counseling than patients in a typical IPT program. Nevertheless, these findings provide some reassurance to public health officials who are considering scaling up IPT in similar clinical settings.

— Shahin Lockman, MD, MSc

Dr. Lockman is Assistant Professor in Medicine, Harvard Medical School, and Associate Physician in Medicine, Brigham and Women's Hospital, Boston.

Published in Journal Watch HIV/AIDS Clinical Care February 1, 2010

Citation(s):

Mosimaneotsile B et al. Isoniazid tuberculosis preventive therapy in HIV-infected adults accessing antiretroviral therapy: A Botswana experience, 2004–2006. J Acquir Immune Defic Syndr 2009 Nov 20; [e-pub ahead of print]. (http://tinyurl.com/yfx8geb)

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• TB chemoprophylaxis
  José Gros-Aymerich, SERMAS, 18 Feb 2010 7:13 AM EST
  Some years ago, an spanish group published results on Rifampicine + Isoniazide ChP for VIH positive pts with a positive... [more]