Evaluation of a School-Based Tuberculosis-Screening Program and Associate Investigation Targeting Recently Immigrated Children in a Low-Burden Country

Abstract

In countries with a low incidence of tuberculosis (TB), screening programs targeting recent immigrants from TB-endemic countries have been shown to be effective in further reducing TB incidence; however, evaluative data on some aspects of these programs remain sparse. We sought to retrospectively evaluate a school-based screening program targeting children at high risk for TB infection in Montreal, Canada, as well as subsequently investigate family and household associates of the schoolchildren with latent TB infection (LTBI), based on adherence to LTBI therapy and cost-benefit analysis. Newly arrived immigrant children (aged 4-18 years) in selected schools were screened for LTBI by using the tuberculin skin test (TST). The TST was defined as positive at an induration of > or =10 mm. Each child who tested positive on the TST was referred for medical evaluation. Family and household associates of the TST-positive child also were screened for LTBI. Classroom attendance sheets and medical charts were reviewed for 16 elementary and secondary schools that comprised the school-screening program of the Montreal Children's Hospital from 1998 to 2003. Medical charts of the child associates (<18 years old) who were screened were reviewed also. The main outcome measures were TST-positivity rate, rate of adherence to LTBI therapy, estimation of factors associated with adherence, and net cost/benefit of the school-screening and associate-investigation programs, both respectively and as a combined program, compared with the cost of passive treatment of TB disease. Of 2524 immigrant children screened, 542 (21%) were TST-positive. Of 342 children started on therapy, 316 (92%) demonstrated adequate adherence. The only predictor of adherence among the schoolchildren was having > or =2 family members brought in for TB screening (adjusted odds ratio: 2.0; 95% confidence interval: 1.3-3.3). There were 599 associates investigated from the 484 TST-positive schoolchildren seen at the TB clinic. Of 555 associates with TST results, 211 (38%) were found to be TST-positive. Of 136 TST-positive child associates, 131 were seen at the Montreal Children's Hospital TB clinic and had their chart reviewed. Of these, 108 (82%) were started on LTBI therapy, and 78 (79%) of 99 of those children with information complied adequately with their therapy. We found net benefits from both school-based screening and associate investigation, both as stand-alone programs and as 1 coordinated, targeted TB-screening program. We demonstrated the effectiveness, including cost-effectiveness, of a targeted, school-based screening program in a low-burden country and the extra benefit given by adding associates to such a program.