Prevalence of positive tuberculin skin tests in foreign‐born children

Abstract

Aims: To evaluate the prevalence of positive tuberculin skin tests (TST) in internationally adopted and immigrant children. To identify risk factors for positive TST in these populations. Methods: The study was a retrospective medical record review in a tertiary care pediatric hospital. All children evaluated at the International Adoption and Immigrant Health Clinic of CHU Sainte-Justine in Montreal, Canada, between 01-01-1998 and 31-12-2001 were included. Demographic and anthropometrical data, BCG vaccination, TST, chest X-ray results and treatment were extracted from the medical records of the patients and analyzed. Positive TST was defined as induration = 10 mm, 48 to 72 hours after injection of five tuberculin units of purified protein derivate. Results: Our population included 670 children: 112 immigrants and 558 adoptees. Median age was 6.9 years for immigrants and 1.1 years for adopted children. Overall incidence of positive TST was 12.2% in our cohort: 31% in the immigrant and 8% in the adopted children groups. There was one case of active tuberculosis. Older age on arrival in Canada and BCG vaccination were identified as risk factors for positive TST in our multivariate model. For each one-year increase in age on arrival in Canada, there was a 1.2 times greater risk for positive TST. Conclusions: Latent tuberculosis is a frequent problem in foreign-born children. The higher incidence in immigrant children can be explained by older age on arrival.