UBC Theses and Dissertations
Reducing the tuberculosis burden in migrant populations through latent tuberculosis infection interventions : a series of cost-effectiveness analyses Campbell, Jonathon
BACKGROUND: In many low tuberculosis (TB) incidence countries, TB rates have stagnated. In these countries, TB disproportionately affects migrant populations due to reactivation of latent TB infection (LTBI) acquired prior to immigration. Treatment of LTBI can significantly reduce risk of TB. The objective of this thesis is to determine the performance of common LTBI diagnostic tests in migrant populations and evaluate the cost-effectiveness of LTBI screening and treatment at various stages of the migration process and in migrants with chronic diseases, such as chronic kidney disease (CKD), that increase risk of TB. METHODS: A literature search determined the sensitivity of LTBI diagnostic tests: the tuberculin skin test (TST) and interferon-gamma release assay (IGRA). A meta-analysis was completed to determine the proportion of migrants testing positive with TST and IGRA from countries of various TB incidences. Discrete event simulation models evaluated the cost-effectiveness of LTBI screening and treatment in migrants: immediately post- immigration, prior to immigration, and at time of late stage CKD diagnosis or dialysis initiation. Incremental cost- effectiveness ratios (ICERs) were calculated for quality-adjusted life years. RESULTS: Sensitivities of 88.9% and 78.2% were found for the IGRA and TST, respectively. Fewer migrants test positive with an IGRA compared with a TST. Immediately after immigration, no LTBI screening was cost-effective when applied universally to all migrants (ICERs >$138,484), but can reduce the TB burden in migrants >20%. IGRA screening pre-immigration and rifampin treatment post-arrival can reduce the TB burden by >40% and results in ICERs <$49,035 compared to no screening in migrants from countries with a TB incidence ≥30 per 100,000. Likewise, in migrants from countries with a TB incidence ≥30 per 100,000, IGRA screening and isoniazid treatment at time of dialysis initiation was dominant and in migrants ≥60 years of age at late stage CKD diagnosis resulted in ICERs <$47,554. CONCLUSIONS: In order to sustainably reduce the migrant TB burden in low incidence countries, LTBI screening should be performed with an IGRA. LTBI screening should be targeted to migrants from countries with a TB incidence ≥30 per 100,000 pre-immigration or at high-risk of TB post-arrival, such as dialysis patients.
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