Fröberg Gabrielle, Wahren Borgström Emilie, Chryssanthou Erja, Correia-Neves Margarida, Källenius Gunilla, Bruchfeld Judith
Division of Infectious Diseases, Dept of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
Dept of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
ERJ Open Res. 2019 Jun 10;5(2). doi: 10.1183/23120541.00078-2019. eCollection 2019 Apr.
Tuberculosis (TB) elimination programmes need to target preventive treatment to groups with an increased risk of TB activation, such as individuals with a latent tuberculosis infection (LTBI) acquired recently. Current diagnostic tests for LTBI have poor predictive values for TB activation and there is, at present, no reference method to evaluate new LTBI diagnostic and prognostic tools. Thus, our objective was to develop a mathematical model, independent of currently available diagnostic tests, to estimate the individual probability of recent and/or remote LTBI. Estimations of recent LTBI were based on the contagiousness of index case, proximity and time of exposure, and environmental factors. Estimation of remote LTBI was based on country of origin, previous stays in high-risk environments or known exposure to TB. Individual probabilities were calculated and compared with tuberculin skin test (TST) and interferon-γ release assay results for 162 contacts of 42 index TB cases. Probabilities of remote LTBI were 16% for European/American contacts and 38% for African/Asian contacts. The probability of recent LTBI was 35% for close contacts to smear microscopy positive index cases. A higher probability of remote LTBI was seen among TST-positive contacts. This model may, with further validation, be used as an independent tool to evaluate new diagnostic markers for recent LTBI.
结核病消除计划需要将预防性治疗目标对准结核病激活风险增加的群体，比如近期获得潜伏性结核感染（LTBI）的个体。目前针对LTBI的诊断测试对结核病激活的预测价值较差，而且目前没有评估新的LTBI诊断和预后工具的参考方法。因此，我们的目标是开发一个独立于现有诊断测试的数学模型，以估计近期和/或既往LTBI的个体概率。近期LTBI的估计基于索引病例的传染性、接触的距离和时间以及环境因素。既往LTBI的估计基于原籍国、既往在高风险环境中的停留情况或已知的结核病接触史。计算个体概率，并将其与42例索引结核病病例的162名接触者的结核菌素皮肤试验（TST）和干扰素-γ释放试验结果进行比较。欧洲/美洲接触者既往LTBI的概率为16%，非洲/亚洲接触者为38%。涂片显微镜检查阳性索引病例的密切接触者近期LTBI的概率为35%。TST阳性接触者中既往LTBI的概率更高。该模型经过进一步验证后，可作为评估近期LTBI新诊断标志物的独立工具。
