Risk factors for development of tuberculosis after isoniazid chemoprophylaxis in human immunodeficiency virus-infected patients.

The long-term benefit of isoniazid chemoprophylaxis in human immunodeficiency virus (HIV)-infected patients and risk factors for isoniazid failure were studied in 131 HIV-infected patients who received >9 months of isoniazid preventive therapy. During a median follow-up of 43 months, 8 patients developed tuberculosis (TB) (6%; 0.61 cases per 100 patient-years). Only the persistence of risk factors for exposure to TB was statistically associated with development of disease (relative hazard, 3.17; 95% confidence interval, 1.56-17; P<.001). Our data suggest reinfection as the main cause of TB after isoniazid prophylaxis.