Department of Respiratory Medicine, Tuberculosis Research Unit, National Heart and Lung Institute, Imperial College London, London, UK.
Thorax. 2013 Mar;68(3):230-9. doi: 10.1136/thoraxjnl-2011-201542. Epub 2012 Jun 12.
UK tuberculosis (TB) notifications are rising due to disease in the immigrant population. National screening guidelines have been revised but cost-effectiveness analyses are hampered by the lack of data on the comparative performance of tuberculin skin tests (TSTs) and interferon γ release assays (IGRAs) in immigrants.
Three-way evaluation of TSTs and two IGRAs (QuantiFERON Gold in-tube (QFN-GIT) and T-SPOT.TB) in immigrants aged ≥16 years to quantify test positivity, concordance and factors associated with positivity. Yields were computed at different incidence thresholds and the relative cost-effectiveness of screening was estimated using different latent TB infection (LTBI) screening modalities at varying incidence thresholds with or without port-of-arrival chest x-ray (CXR).
231 immigrants were included; median age 29 (IQR 24-37). TSTs were accepted by 80.9%, read in 93.5% and 30.3% were positive - QFN-GIT and T-SPOT.TB positive in 16.6% and 22.5% respectively. Positive TSTs, QFN-GIT and T-SPOT.TB were independently associated with increasing TB incidence in immigrants' countries of origin (p=0.007, 0.007, 0.037 respectively). Implementing current guidance (threshold 40/100 000 per year) would identify 98-100% of LTBIs (depending on test) but entail testing 97-99% of the cohort; screening at 150/100 000 per year would identify 49-71% of LTBIs but only entail screening half the cohort. The two most cost-effective screening strategies were no port-of-entry chest radiography and screen with single-step QFN-GIT at 250/100 000 per year (incremental cost-effectiveness ratio (ICER)) £21 565.3/case averted); and no port-of-entry CXR and screen with single-step QFN-GIT at 150/100 000 per year (averted additional 7.8 TB cases; ICER £31 867.1/case averted).
UK immigrant screening could cost-effectively and safely eliminate mandatory CXR on arrival by emphasising systematic screening for LTBI with single-step IGRA. Intermediate incidence thresholds balance the need to identify as many imported LTBIs as possible against limited service capacity.
由于移民人群中的疾病，英国的结核病（TB）报告病例正在增加。国家筛查指南已经修订，但由于缺乏有关结核菌素皮肤试验（TST）和干扰素 γ 释放测定（IGRAs）在移民人群中的比较性能的数据，因此成本效益分析受到阻碍。
对≥16 岁的移民进行三种 TST 和两种 IGRAs（QuantiFERON Gold in-tube（QFN-GIT）和 T-SPOT.TB）的评估，以量化检测阳性率、一致性以及与阳性相关的因素。在不同的发病率阈值下计算了产量，并使用不同的潜伏性结核感染（LTBI）筛查方式在不同的发病率阈值下（有无入境时的胸部 X 光检查（CXR）），评估了筛查的相对成本效益。
共纳入 231 名移民；中位年龄 29（IQR 24-37）。80.9%的人接受了 TST，93.5%的人进行了 TST 读数，30.3%的人呈阳性 - QFN-GIT 和 T-SPOT.TB 的阳性率分别为 16.6%和 22.5%。TST、QFN-GIT 和 T-SPOT.TB 的阳性结果与移民原籍国的 TB 发病率增加独立相关（p=0.007、0.007、0.037）。实施当前指南（每年 40/100 000）将确定 98-100%的 LTBI（取决于检测），但需要对 97-99%的队列进行检测；每年筛查 150/100 000 将确定 49-71%的 LTBI，但只需筛查一半的队列。两种最具成本效益的筛查策略是没有入境时的胸部 X 光检查和使用一步法 QFN-GIT 筛查，每年筛查 250/100 000（增量成本效益比（ICER）为 21 565.3/例避免）；没有入境时的 CXR 检查和使用一步法 QFN-GIT 筛查，每年筛查 150/100 000（避免了 7.8 例额外的 TB 病例；ICER 为 31 867.1/例避免）。
通过强调使用一步法 IGRAs 对 LTBI 进行系统筛查，英国移民筛查可以在安全且具有成本效益的情况下消除入境时强制性的 CXR。中间发病率阈值平衡了尽可能多地发现输入性 LTBI 的需求与有限的服务能力。
