Background: Patients with positive sputum smears are those with the capacity to spread infection. The objective of this study was to describe the incidence of tuberculosis in Catalonia (an autonomous community in the northeast of Spain which includes Barcelona) and to determine risk factors associated to patients with positive sputum smear test.
Methods: New cases of tuberculosis detected by active surveillance between May 1996 and April 1997 were studied. The study was analysed as a coincident cases and controls study. The rate of incidence was calculated per 100,000 persons-year. The association of the dependent variable--case of tuberculosis with positive sputum smear--with the remainder of independent variables was determined by odds ratio (OR) with a 95% confidence interval (CI).
Results: A total of 2508 cases of tuberculosis were detected. The rate of incidence was 41.4 per 100,000 persons-year. Of these 19.4% (487/2508) were coinfected with HIV and 35.6% (893/2508) presented a positive sputum smear, which implies a rate of 14.7 per 100,000 persons-year. In an adjusted multivariate analysis, cases with positive smears were positively associated with the 15-24 (OR=1.9; 95% CI: 1.4-2.4), 25-34 (OR=2.1; 95% CI: 1.7-2.7) and 35-44 years (OR=1.7; 95% CI: 1.3-2.2) age compared with persons 45 years old and above; with males (OR=1.8; 95% CI: 1.5-2.2) and consumers of alcohol (OR=2.1; 95% CI: 1.7-2.7) and negatively with those under 15 years of age (OR=0.1; 95% CI: 0.1-0.2) and coinfection with HIV (OR=0.5; 95% CI: 0.3-0.7).
Conclusions: Measures to control tuberculosis transmission (prompt diagnosis, study of contacts and directly observed treatments) should be reinforced for male adults with excessive consumption of alcohol.