Diagnostic efficacy of the study of contacts of tuberculosis patients in ahigh prevalence urban area

Background. The investigation of contacts (CI) is a main objective for the control of tuberculosis (TB) after therapeutic compliance. The present stud y was planned to determine the diagnostic effectiveness and degree of CI im plementation as well as risk factors to generate new cases in a high preval ence area (163/10(5)). Patients and methods. An analysis was made of the available data of CI in t he Barcelona district of Ciutat Vella in 1997 and 1998. The odds ratio (OR) was calculated as a measure of the association with infection and tubercul osis disease with a 95% confidence interval (CI) by logistic regression. Results. CI was made in 65.2% of patients and 100% of tuberculin-positive c hildren. Thirty patients were diagnosed among 858 contacts of 135 tuberculo sis patients (3.49%) and 8 among 318 contacts of 64 primoinfected children aged less than 15 years (2.51%). Prevalence of tuberculosis infection was 5 1.51% and 46.85% respectively. The characteristics of the index case associ ated 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 sput um acid-fast smears and degree of closeness except for contacts aged less t han 20 years. Conclusions. CI is cost-effective in this area of high prevalence and shoul d 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.