Risk factors for and attributable mortality from tuberculosis in patients with hematologic malignances.

BACKGROUND AND OBJECTIVES Patients with hematologic malignancies are at increased risk of developing tuberculosis because of the T-cell immunodeficiency associated with the disease and/or its treatment. The objective of this study was to evaluate risk factors, clinical findings and the attributable mortality associated with tuberculosis in patients with hhematologic malignancies. DESIGN AND METHODS We performed a retrospective review of the clinical records of 917 patients observed between 1990 and 2000. A risk classification for tuberculosis (low vs. high risk) was developed based on the underlying disease and previous exposure to agents that deplete T-cell mediated immunity. Patients with and without tuberculosis were compared by univariate and multivariate analyses with regard to demographic and clinical characteristics, underlying diseases and their treatment. The attributable mortality was assessed by matching cases and controls using the independent variables identified as risk factors as the matching parameters, and was estimated by subtracting the crude mortality of the controls from the crude mortality of the cases. RESULTS We found 24 cases of tuberculosis (2.6%). Risk factors by multivariate analysis were malnutrition (OR 55.66, 95% CI 2.47--1254.82), use of fludarabine (OR 6.08, 95% CI 1.22--30.25), use of corticosteroids (OR 5.32, 95% CI 1.15--24.39) and belonging to the high-risk group (OR 3.73, 95% CI 1.09--12.76). The crude mortality of patients with tuberculosis was 75%, and the attributable mortality was 62.5% (risk ratio 6.0, 95% CI 2.03--17.70). INTERPRETATION AND CONCLUSIONS The mortality attributable to tuberculosis is high in patients with hematologic malignancies. The identification of risk factors may be useful for evaluating strategies to be applied in high-risk patients.