To evaluate adherence and safety of three regimens of chemoprophylaxis for tuberculosis (TB) in HIV-infected patients with positive tuberculin skin test.

DESINGS: We performed a randomised, comparative and open clinical assay carried out in 316 HIV-infected patients. The patients were randomly assigned to one of three regimens, 108 to isoniazid for six months (6H), 103 to rifampin and isoniazid for three months (3RH), and 105 to pyrazinamide and rifampin for two months (2RZ).

RESULTS: The TB rates (cases per 100 persons/year) in the three treatment groups were 3.4 in 6H, 4.5 in 3RH and 1.9 in 2RZ. The relative risk for TB with 6H as compared with 2RZ was 1.76, and with 3RH, 2.34. Twenty-seven percent of the patients voluntarily abandoned chemoprophylaxis and 9.7% were withdrawn due to adverse side-effects. Seven patients were withdraw due to hepatotoxicity (5 in 6H, 2 in 3RH and 0 in 2RZ). No appreciable differences were found among the three regimens.

CONCLUSION: In our study the 2RZ regimen was as safe as the 6H and 3RH regimens. We have nor observed a higher incidence of hepatotoxicity in patients who received 2RZ.

Inclusion Criteria:

• HIV infection confirmed by ELISA and Western blot
• Age between 18 and 65 years
• Life expectancy greater than two years
• Reactivity to PPD > 5 mm

Exclusion Criteria:

• Presence of active tuberculosis
• Background of previous antituberculosis therapy or chemoprophylaxis
• Presence of symptoms or signs suggesting pulmonary or extra-pulmonary tuberculosis
• History of hypersensitivity to the drugs used in the study (isoniazid, rifampin or pyrazinamide)
• Aspartate-aminotransferase and/or alanine-aminotransferase plasma concentrations more than or equal to four times their normal values, total bilirubin more than 2 mg/ml, and/or creatinine more than 2 mg/ml
• Pregnancy
• Undergoing treatment incompatible with any of the drugs used in the study.