Mycobacterium tuberculosis infection in patients with systemic rheumatic diseases. A case-series.

OBJECTIVE: To describe the clinical characteristics of patients with systemic rheumatic diseases and tuberculosis. A retrospective case series from 1987 to 1994, drawn from a tertiary-care hospital in Mexico City, was studied. RESULTS: Thirty patients were included (20 women, 10 men), with mean age of 39.8 years (range 14-66), and a mean duration of the systemic rheumatic disease of 44 months (1-372). The rheumatic diseases included systemic lupus erythematosus (SLE) (n = 13), rheumatoid arthritis (7), polymyositis or dermatomyositis (5), and other diseases (5). During the six months previous to the diagnosis of tuberculosis, 22 patients had received corticosteroids, and 13 others immunosuppressants. Mycobacterium tuberculosis was isolated from 18 patients. Pulmonary tuberculosis was found in 10 patients, and extrapulmonary tuberculosis in 20, seven of these with miliary disease. SLE was seen in 6 of the patients with miliary tuberculosis. The clinical manifestations were: fever (67%), weight loss (67%), diaphoresis (60%), cough and sputum (53%), lymph node enlargement (43%), and dyspnea (33%). Sixteen patients had an abnormal chest film. Of 18 patients tested by PPD RT-2, 8 had an induration > 10 mm. Patients were initially treated with 3 or 4 anti-tuberculosis drugs for 15 days to 6 months, followed by 6 to 10 months of isoniazid plus rifampicin. Three relapsed, and 2 died of respiratory failure. CONCLUSIONS: This case series showed a particular pattern of tuberculosis in patients with systemic rheumatic diseases.

Tuberculosis prophylaxis in patients with steroid treatment and systemic rheumatic diseases. A case-control study.

OBJECTIVE: The aim of this study was to assess the impact of isoniazid prophylaxis in patients with systemic rheumatic diseases who attended a teaching hospital in Mexico City between 1987 and 1992. METHODS: In this case-control study, patients with systemic rheumatic diseases and tuberculosis (cases) were compared with patients with systemic rheumatic diseases without tuberculosis (controls). The groups were matched by year of hospital admission and rheumatic disease. Clinical charts were reviewed for: 1) isoniazid prophylaxis, defined as the administration of isoniazid 300 mg/day for 6 or more months in patients with exposure to steroids (prophylaxis with isoniazid was defined as complete, incomplete or any prophylaxis); 2) exposure to steroids: defined as the administration of prednisone > 15 mg/day (or its equivalent of another steroid) for 3 or more months before tuberculosis or recruitment into the study; 3) exposure to immunosuppressants, defined as the administration of any dose of azathioprine, methotrexate, cyclophosphamide, and/or 6-mercaptopurine, before tuberculosis in the cases or recruitment date in the controls; 4) reactivity to PPD; and 5) other relevant variables. RESULTS: Twenty cases and 66 controls were studied. A 70% decrease in the risk of developing tuberculosis was found among patients who received any prophylaxis with isoniazid as compared to controls: OR 0.31, 95% CI 0.09-0.98, p = 0.03. A 97% decrease was seen in those patients who received complete prophylaxis: OR 0.034, 95% CI 0.0001-0.216, p < 0.0001. The protective effect of complete prophylaxis persisted even after controlling for other potential confounders, such as age, gender, rheumatic disease, duration of rheumatic symptoms, and exposure to steroids and/or immunosuppressants. CONCLUSION: The results of this study suggest that in countries with a high prevalence of tuberculosis the use of isoniazid (300 mg/day for 6 months) in rheumatic patients with exposure to prednisone (> 15 mg/day for three or more months) may be useful to prevent tuberculosis, independently of the results of the PPD reactivity test. However, a controlled clinical trial will be required to confirm these results.