Perry Sharon, Sanchez Luz, Yang Shufang, Agarwal Zubin, Hurst Philip, Parsonnet Julie
Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California 94305-5407, USA.
Clin Vaccine Immunol. 2008 Mar;15(3):425-32. doi: 10.1128/CVI.00398-07. Epub 2008 Jan 16.
Studies are needed to characterize the reproducibility of QuantiFERON-TB Gold (QFT-G) for targeted U.S. screening populations. Members of northern California households were tested with the QFT-G in-tube assay (QFT-G-IT) at two home visits 3 months apart. Reproducibility and agreement with the tuberculin skin test (TST) were assessed. Monte Carlo simulation was used to evaluate the role of test-related error. Of 63 individuals (49 adults and 14 children) completing QFT-G-IT at both time points, 79% were foreign-born (98% from Latin America) and 68% reported Mycobacterium bovis BCG vaccination. At the baseline visit, 23 (37%) were TST positive and 15 (24%) were QFT-G-IT positive (kappa = 0.48 [+/- 0.11]). At 3 months, 3/48 (6.3%; 95% confidence interval [95CI], 2 to 17) of those initially QFT-G-IT negative converted, and 5/15 (33%; 95CI, 15 to 58) of those initially QFT-G-IT positive reverted. Among the 8 individuals with inconsistent QFT-G-IT results, the maximum gamma interferon response at either visit was 0.68 IU/ml versus means of 4.99 (+/- 3.74) and 6.95 (+/- 5.6) for 10 persistent positives at the first and second visits, respectively. Expected false-reversion and -conversion rates were 32% (90CI, 25 to 39%) and 6.95% (90CI, 4.6 to 9.8%) when the sensitivity and specificity were assumed to average 70% and 98%, respectively. Transient responses to QFT-G-IT are common, and low positive results need to be interpreted with caution. Further studies are needed to characterize the predictive value of the test for U.S. foreign-born and other targeted screening populations.
需要开展研究以明确针对美国目标筛查人群的全血γ-干扰素释放试验（QFT-G）的可重复性。对北加利福尼亚州家庭的成员进行了QFT-G管内检测法（QFT-G-IT）检测，在间隔3个月的两次家访时分别进行检测。评估了其可重复性以及与结核菌素皮肤试验（TST）的一致性。采用蒙特卡洛模拟来评估检测相关误差的作用。在两个时间点均完成QFT-G-IT检测的63名个体（49名成人和14名儿童）中，79%为外国出生（98%来自拉丁美洲），68%报告接种过牛分枝杆菌卡介苗（BCG）。在基线访视时，23名（37%）TST呈阳性，15名（24%）QFT-G-IT呈阳性（kappa值 = 0.48 [±0.11]）。在3个月时，最初QFT-G-IT阴性的人群中有3/48（6.3%；95%置信区间[95CI]，2%至17%）出现转换，最初QFT-G-IT阳性的人群中有5/15（33%；95CI，15%至58%）出现逆转。在QFT-G-IT结果不一致的8名个体中，两次访视中任一访视时最大γ-干扰素反应为0.68 IU/ml，而第一次和第二次访视时10名持续阳性个体的平均反应分别为4.99（±3.74）和6.95（±5.6）IU/ml。当假设敏感性和特异性平均分别为70%和98%时，预期的假逆转率和假转换率分别为32%（90CI，25%至39%）和6.95%（90CI，4.6%至9.8%）。对QFT-G-IT的短暂反应很常见，低阳性结果需要谨慎解读。需要进一步开展研究以明确该检测方法对美国外国出生人群及其他目标筛查人群的预测价值。
