Cost Effectiveness of Interferon-Gamma Release Assay for School-Based Tuberculosis Screening

Abstract

To assess the cost effectiveness of school-based tuberculosis (TB) screening using QuantiFERON®-TB Gold In-Tube (QFT) versus the tuberculin skin test (TST) and chest x-ray examination (CXR). We constructed Markov models of first-year high-school and university students, using a societal perspective, and followed them up until the age of 80 years. Three strategies (QFT, TST, and CXR) were modeled. All costs and clinical benefits were discounted at a fixed annual rate of 3%. In the base-case analyses of 16-year-old high-school students and 19-year-old university students, the QFT strategy yielded the greatest benefits at the lowest cost [in year 2009 values] (16-year-olds: $US627.89, 29.69835 quality-adjusted life-years [QALYs]; 19-year-olds: $US646.04, 29.15361 QALYs), compared with the TST strategy (16-year-olds: $US943.50, 29.69767 QALYs; 19-year-olds: $US998.62, 29.15288 QALYs) and the CXR strategy (16-year-olds: $US7286.24, 29.69532 QALYs; 19-year-olds: $US7305.19, 29.14911 QALYs). On one-way sensitivity analyses, the bacillus Calmette-Guérin (BCG) vaccination rate was not sensitive to the TST strategy. On probabilistic sensitivity analysis, the QFT strategy was the most cost effective, with a willingness-to-pay level of $US50 000/QALY gained. The QFT strategy provided the greatest benefits at the lowest cost for school-based TB screening. There appears to be little role for TST or CXR in screening of school populations. Current practices using either TST or CXR screening should be reconsidered on the basis of cost effectiveness.