Tuberculosis, focussed tools and the right schools: estimated impact and cost of a targeted student screening programme for tuberculosis infection.

BACKGROUND: The World Health Organization (WHO) recommends targeted screening for latent tuberculosis infection (LTBI) among high-risk populations. Recent studies that evaluate targeted school-based programmes in low burden settings are scarce. AIMS: To evaluate a school screening programme for recently arrived migrant students from moderate and high tuberculosis (TB) burden countries and estimate (1) the number of cases of active TB that were prevented and (2) the cost per case of active TB prevented. METHODS: Students were screened with tuberculin skin tests (TST) at schools with a high migrant population intake. Those with positive results were referred for specialist evaluation. Outcomes were retrospectively assessed using 5 years of prospectively collected data. Cost data were collected. Main outcomes measured were the number of children were diagnosed with LTBI who completed treatment, and programme costs. RESULTS: Of 4728 student screened, 295 (6.2%) were diagnosed with LTBI. Of these, 273 (92.5%) were offered preventive therapy, 242 (82.0%) commenced and 204 (69.2%) completed therapy. The number needed to screen (NNS) was 23 per completed course of preventive treatment for LTBI. Assuming a 10% lifetime risk of reactivation, the NNS was 386 per case of TB disease notification avoided. The cost of screening was A$23 932 per case of TB disease avoided. CONCLUSIONS: This TB strategy is supported by the high rate of TB infection in the student group, the treatment uptake and completion rates. Cost-benefit is linked with lifetime risk of TB reactivation. Targeted school screening programmes represent an important opportunity for TB control in low-burden settings.