Eficacia diagnóstica del estudio de contactos de enfermos tuberculosos en un distrito urbano de alta prevalencia

Background. The investigation of contacts (CI) is a main objective for the control of tuberculosis (TB) after therapeutic compliance. The present study was planned to determine the diagnostic effectiveness and degree of CI implementation as well as risk factors to generate new cases in a high prevalence area (163/10⁵). Patients and methods. An analysis was made of the available data of CI in the Barcelona district of Ciutat Vella in 1997 and 1998. The odds ratio (OR) was calculated as a measure of the association with infection and tuberculosis disease with a 95% confidence interval (CI) by logistic regression. Results. CI was made in 65.2% of patients and 100% of tuberculin-positive children. Thirty patients were diagnosed among 858 contacts of 135 tuberculosis patients (3.49%) and 8 among 318 contacts of 64 primoinfected children aged less than 15 years (2.51%). Prevalence of tuberculosis infection was 51.51% and 46.85%, respectively. The characteristics of the index case associated with new patients were drug abuse (OR: 11.16; CI: 3.0-40.9) and to be prisoner (OR: 18.7; CI: 1.5-232.9). No influence was detected regarding sputum acid-fast smears and degree of closeness except for contacts aged less than 20 years. Conclusions. CI is cost-effective in this area of high prevalence and should be performed in every TB case although priority groups are prisoners and/or drug abusers and contacts aged less than 20 years. The implementation of CI can be improved in our setting.