Cost-effectiveness of the NICE guidelines for screening for latent tuberculosis infection: the QuantiFERON-TB Gold IGRA alone is more cost-effective for immigrants from high burden countries

Abstract

NICE (National Institute for Health and Clinical Excellence) guidelines for new entrant tuberculosis (TB) screening recommend chest x ray (CXR) for immigrants from countries with TB incidence >40/10(5), and tuberculin skin test (TST) for people with normal CXR from very high TB prevalence countries. A revised screening policy using first-line QuantiFERON-TB Gold (QFT) in high risk immigrants was piloted in 2007. Initially, TST was offered to immigrants from countries with TB incidence 200-339/10(5), and QFT to those from countries with incidence >340/10(5). When increased resources became available, all immigrants from countries with TB incidence >200/10(5) had QFT. Those with positive QFT were invited for CXR. 1336 immigrant were invited for screening, with a 32% attendance rate. 280 patients had QFT, of which 38% were positive, with <2% being indeterminate. Using the NICE approach, the cost of screening these 280 immigrants would be pound 13,346.75 ( pound 47.67 per immigrant) and would identify 83 cases of latent TB infection (LTBI). Using first-line QFT followed by CXR the cost was pound 9781.82 ( pound 34.94 per immigrant) and identified 105 cases of LTBI. The cost to identify one case of LTBI following NICE guidelines would be pound 160.81 and using the present protocol was pound 93.16. For immigrants from high risk countries QFT blood testing followed by CXR is feasible for TB screening, cheaper than screening using the NICE guideline and identifies more cases of LTBI.