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Free Content Characteristics of tuberculosis patients who generate secondary cases

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OBJECTIVE: To determine the characteristics of smear positive tuberculosis (TB) patients who generate secondary TB cases.

METHODS: Those smear positive TB patients detected by the Barcelona Tuberculosis Program between 1990–1993, and for whom contact studies had been performed, were studied. We analyzed the predictive role of the variables: age, sex, intravenous drug use (IVDU), the presence of the acquired immune deficiency syndrome (AIDS), human immunodeficiency virus (HIV) infection, radiology pattern, district of residence, history of imprisonment, alcoholism, smoking, history of TB, treatment compliance and the number of secondary cases generated. Statistical analysis was based on the logistic regression model, calculating the odds ratios (OR) with 95% confidence intervals (CI).

RESULTS: Of the 1079 patients studied, 78 (7.2%) had generated only one secondary case, and 30 (2.8%) two or more. The variables associated with generating two or more secondary cases were: IVDU (P < 0.001; OR = 4.06; CI: 1.80–9.15), cavitary radiology pattern (P = 0.002; OR = 3.69; CI: 1.62–8.43), and age (P = 0.016; OR = 0.98; CI 0.96–0.99). When we examined those who had generated one or more secondary cases, the following variables were significant: IVDU (P = 0.043; OR = 1.75; CI: 1.02–3.02), cavitary radiology pattern (P < 0.001; OR = 3.07; CI: 1.98–4.77) and age (P < 0.001; OR = 0.98; CI: 0.97–0.99).

CONCLUSION: The study of the contacts of smear positive TB patients allows us to detect an important number of secondary cases. Young adults, those with cavitary radiology pattern, and IVDU are more likely to generate secondary cases.

Keywords: HIV; contact study; drug use; micro-epidemic; predictive factors; secondary cases; smear positive; transmission; tuberculosis

Document Type: Regular Paper

Affiliations: Department of Epidemiology, Municipal Institute of Health, Barcelona, Barcelona Tuberculosis Investigation Unit, Barcelona, Spain

Publication date: 1997-08-01

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  • The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.

    Certain IJTLD articles are selected for translation into French, Spanish, Chinese or Russian. They are available on the Union website

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