Tuberculosis and silicosis: epidemiology, diagnosis and chemoprophylaxis.
Silicosis, the most prevalent of the pneumoconioses, is caused by inhalation of crystalline silica particles. Silica-exposed workers, with or without silicosis, are at increased risk for tuberculosis and nontuberculous mycobacteria-related diseases. The risk of a patient with silicosis developing tuberculosis is higher (2.8 to 39 times higher, depending on the severity of the silicosis) than that found for healthy controls. Various regimens for tuberculosis chemoprophylaxis in patients with silicosis have been studied, all of which present similar efficacy and overall risk reduction to about one half of that obtained with placebo. Long-term regimens have potential side effects (particularly hepatotoxicity). In addition, the use of such regimens can jeopardize adherence to treatment. The current guidelines recommend that tuberculin skin tests be performed, and, if positive, that chemoprophylaxis be instituted. There are several possible regimens, varying in terms of the drugs prescribed, as well as in terms of treatment duration. We recommend the use of isoniazid at 300 mg/day (or 10 mg/kg/day) for six months for patients with silicosis, as well as for healthy patients with periods of exposure to silica longer than 10 years and strongly positive tuberculin skin test results (induration > or = 10 mm). Nevertheless, further studies are necessary so that indications, drugs, doses and duration of chemoprophylaxis regimens can be more properly defined.
Barboza
Carlos Eduardo Galvão
CE
Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil. cebarboza@hotmail.com
Winter
Daniel Hugo
DH
Seiscento
Márcia
M
Santos
Ubiratan de Paula
Ude P
Terra Filho
Mário
M
D000904:Antibiotics, Antitubercular / Q000627:therapeutic use; D001938:Brazil / Q000453:epidemiology; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use; D016273:Occupational Exposure / Q000009:adverse effects; D011718:Pyrazinamide / Q000627:therapeutic use; D012293:Rifampin / Q000627:therapeutic use; D012822:Silicon Dioxide / Q000009:adverse effects; D012829:Silicosis / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D012830:Silicotuberculosis / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology
D000904:Antibiotics, Antitubercular; D011718:Pyrazinamide; D012822:Silicon Dioxide; D007538:Isoniazid; D012293:Rifampin