Wang L, Turner M O, Elwood R K, Schulzer M, FitzGerald J M
Center for Disease Control Society, Respiratory Division, University of British Columbia, Vancouver, Canada.
Thorax. 2002 Sep;57(9):804-9. doi: 10.1136/thorax.57.9.804.
The accurate diagnosis of latent tuberculosis infection (LTBI) is an important component of any tuberculosis control programme and depends largely on tuberculin skin testing. The appropriate interpretation of skin test results requires knowledge of the possible confounding factors such as previous BCG vaccination. Uncertainty about the effect of BCG vaccination on tuberculin skin testing and the strength with which recommendations are made to individual patients regarding treatment of LTBI have identified a need to analyse the available data on the effect of BCG on skin testing. A meta-analysis of the evidence for the effect of BCG vaccination on tuberculin skin testing in subjects without active tuberculosis was therefore performed.
Medline was searched for English language articles published from 1966 to 1999 using the key words "BCG vaccine", "tuberculin test/PPD", and "skin testing". Bibliographies of relevant articles were reviewed for additional studies that may have been missed in the Medline search. Articles were considered for inclusion in the meta-analysis if they had recorded tuberculin skin test results in subjects who had received BCG vaccination more than 5 years previously and had a concurrent control group. Only prospective studies were considered. The geographical location, number of participants, type of BCG vaccine used, type of tuberculin skin test performed, and the results of the tuberculin skin test were extracted.
The abstracts and titles of 980 articles were identified, 370 full text articles were reviewed, and 26 articles were included in the final analysis. Patients who had received BCG vaccination were more likely to have a positive skin test (5 TU PPD: relative risk (RR) 2.12 (95% confidence interval (CI)1.50 to 3.00); 2 TU RT23: 2.65 [corrected] (95% CI 1.83 to 3.85). The effect of BCG vaccination on PPD skin test results was less after 15 years. Positive skin tests with indurations of >15 mm are more likely to be the result of tuberculous infection than of BCG vaccination.
In subjects without active tuberculosis, immunisation with BCG significantly increases the likelihood of a positive tuberculin skin test. The interpretation of the skin test therefore needs to be made in the individual clinical context and with evaluation of other risk factors for infection. The size of the induration should also be considered when making recommendations for treatment of latent infection.
潜伏性结核感染（LTBI）的准确诊断是任何结核病控制规划的重要组成部分，并且很大程度上依赖于结核菌素皮肤试验。皮肤试验结果的恰当解读需要了解可能的混杂因素，如既往卡介苗接种情况。卡介苗接种对结核菌素皮肤试验的影响存在不确定性，以及针对LTBI治疗向个体患者提出建议的力度，这表明有必要分析卡介苗对皮肤试验影响的现有数据。因此，对卡介苗接种对无活动性结核病受试者结核菌素皮肤试验影响的证据进行了一项荟萃分析。
使用关键词“卡介苗”、“结核菌素试验/PPD”和“皮肤试验”在Medline中检索1966年至1999年发表的英文文章。查阅相关文章的参考文献，以寻找在Medline检索中可能遗漏的其他研究。如果文章记录了5年多以前接受卡介苗接种的受试者的结核菌素皮肤试验结果且有一个同期对照组，则将其纳入荟萃分析。仅考虑前瞻性研究。提取地理位置、参与者数量、使用的卡介苗疫苗类型、进行的结核菌素皮肤试验类型以及结核菌素皮肤试验结果。
共识别出980篇文章的摘要和标题，查阅了370篇全文文章，最终分析纳入了26篇文章。接受卡介苗接种的患者更有可能皮肤试验呈阳性（5 TU PPD：相对风险（RR）2.12（95%置信区间（CI）1.50至3.00）；2 TU RT23：2.65[校正后]（95%CI 1.83至3.85）。15年后卡介苗接种对PPD皮肤试验结果的影响较小。硬结直径>15 mm的阳性皮肤试验更有可能是结核感染而非卡介苗接种的结果。
在无活动性结核病的受试者中，卡介苗免疫显著增加结核菌素皮肤试验阳性的可能性。因此，皮肤试验的解读需要在个体临床背景下进行，并评估其他感染危险因素。在对潜伏感染治疗提出建议时，也应考虑硬结的大小。
