Data from: QuantiFERON®-TB Gold In-Tube for contact screening in BCG-vaccinated adults: a longitudinal cohort study

Objective. To assess the utility of QuantiFERON®-TB Gold In-tube (QFT-GIT) for targeting preventive therapy in BCG-vaccinated contacts of tuberculosis (TB), based on its high specificity and negative predictive value for development of TB.

Methods. We compared two screening strategies for TB contact tracing in two consecutive periods: the tuberculin skin test (TST) period, when all contacts were screened with the TST alone; and the QFT-GIT period, when BCG-vaccinated contacts underwent TST and QFT-GIT. Diagnosis of TB infection among BCG-vaccinated contacts relied on TST ≥5 mm in the TST period, while in the QFT-GIT period either a positive QFT-GIT or a TST ≥15 mm was required.

Measurements and main results. Six hundred and sixty-one contacts were compared. In the QFT-GIT period there was a reduction in diagnoses of TB infection (77.4% vs. 51.2%; p <0.01) and preventive therapy prescribed (62.1% vs. 48.2%; p = 0.02) among the 290 BCG-vaccinated contacts. After a median follow-up of 5 years, cumulative incidences of TB were 0.62 and 0.29 in the TST and QFT-GIT periods respectively (p = 0.59).

Conclusions. In BCG-vaccinated TB contacts, the addition of QFT-GIT safely reduced TB diagnosis and treatment rates without increasing the risk of subsequent active TB.

### 研究目的
旨在评估全血γ干扰素释放试验（QuantiFERON®-TB Gold In-tube，QFT-GIT）用于结核病（Tuberculosis，TB）卡介苗（Bacillus Calmette-Guérin，BCG）接种接触者的预防性治疗靶向筛查的应用价值，其依据为该检测对结核病发病具有较高的特异性与阴性预测值。

### 研究方法
本研究在两个连续阶段中对比了两种结核病接触者追踪筛查策略：结核菌素皮肤试验（Tuberculin Skin Test，TST）阶段，仅采用结核菌素皮肤试验对所有接触者进行筛查；QFT-GIT阶段，对卡介苗接种接触者同时实施结核菌素皮肤试验与QFT-GIT检测。卡介苗接种接触者的结核分枝杆菌感染诊断标准为：TST阶段以TST硬结直径≥5mm为判定依据，QFT-GIT阶段则需满足QFT-GIT结果阳性或TST硬结直径≥15mm。

### 测量指标与主要结果
本研究共纳入661名接触者进行对比分析。在290名卡介苗接种接触者中，QFT-GIT阶段的结核感染诊断率（51.2%）与预防性治疗处方率（48.2%）均显著低于TST阶段的77.4%与62.1%（两组比较，p<0.01；p=0.02）。经中位随访5年后，TST阶段与QFT-GIT阶段的结核病累积发病率分别为0.62与0.29（p=0.59）。

### 研究结论
对于卡介苗接种的结核病接触者，联合QFT-GIT检测可在不增加后续活动性结核病发病风险的前提下，安全降低结核感染诊断与预防性治疗的实施比例。