INRS-Institut Armand-Frappier, Institut national de la recherche scientifique, Laval, Quebec, Canada.
Int J Epidemiol. 2010 Apr;39(2):469-86. doi: 10.1093/ije/dyp307. Epub 2009 Oct 12.
Results have been conflicting as to whether Bacillus Calmette-Guérin (BCG) vaccine, a non-specific stimulator of the immune function, protects, predisposes or is unrelated to the development of childhood asthma. In this systematic review and meta-analysis, we qualitatively and quantitatively appraised the epidemiological evidence.
Eligible studies were identified using a search strategy that included a computerized literature search and a manual search of each article's reference list, up to June 2008. A total of 23 studies were included (10 cohort, 5 case-control and 8 cross-sectional). Each study was summarized and rated for methodological quality. Pooled odds ratio (OR) estimates and 95% confidence intervals (CIs) were calculated using fixed-effects (FE) or random-effects (RE) models; if heterogeneity was present, the latter was used. Three indicators of BCG exposure were considered including BCG vaccination, tuberculin response and scar diameter.
The pooled estimate of association for 23 studies reporting on any of the three indicators suggested a protective effect of BCG exposure on childhood asthma occurrence. The studies were heterogeneous, especially when tuberculin response was considered. Restriction to a subgroup of 16 studies that considered BCG vaccination indicated a protective effect with no evidence of heterogeneity. The overall pooled OR using an FE model was 0.86 (95% CI 0.79-0.93). Exclusion of three studies with the lowest quality scores showed a similar association.
These results strengthen the epidemiological evidence in support of the hypothesis that exposure to the BCG vaccine in early life prevents asthma, possibly through a modulation of the immune maturation process.
卡介苗（BCG）是一种非特异性免疫功能刺激剂，对于其是否能预防、诱发或与儿童哮喘的发展无关，研究结果一直存在争议。在本系统评价和荟萃分析中，我们对流行病学证据进行了定性和定量评估。
我们使用一种检索策略来确定符合条件的研究，该策略包括计算机文献检索和手动检索每篇文章的参考文献列表，检索截至 2008 年 6 月。共纳入 23 项研究（10 项队列研究、5 项病例对照研究和 8 项横断面研究）。对每个研究进行总结和方法学质量评分。使用固定效应（FE）或随机效应（RE）模型计算汇总比值比（OR）估计值和 95％置信区间（CI）；如果存在异质性，则使用后者。考虑了三种卡介苗暴露指标，包括卡介苗接种、结核菌素反应和疤痕直径。
报告了三种指标中的任何一种的 23 项研究的汇总估计值表明，卡介苗暴露对儿童哮喘的发生有保护作用。这些研究存在异质性，尤其是当考虑结核菌素反应时。限制在考虑卡介苗接种的 16 项研究的亚组中，表明有保护作用且没有异质性的证据。使用 FE 模型的总体汇总 OR 为 0.86（95％CI 0.79-0.93）。排除三项质量评分最低的研究后，仍显示出相似的相关性。
这些结果加强了支持卡介苗疫苗早期接种可预防哮喘的假设的流行病学证据，这可能是通过调节免疫成熟过程实现的。
