目的·采用meta分析方法全面评价细胞游离DNA（cell-free DNA，cfDNA）对胆道癌（biliary tract cancer，BTC）的诊断准确性，探究样本来源、检测方法以及截断值选择等对诊断效果的影响，为更好开展临床应用提供依据。方法·检索8个中英文数据库中关于cfDNA对BTC诊断价值的前瞻性或回顾性研究，截止时间为2023年4月。根据纳入和排除标准进行筛选和数据提取，用Spearman秩相关分析评估阈值效应，运用Cochran Q检验、I²检验分析纳入研究间的异质性。拟合双变量混合效应模型，计算总体敏感度、特异度和曲线下面积（area under the curve，AUC）等统计量，判断诊断性能。同时，基于研究类型、样本量大小、检测方式、样本来源和诊断参照标准进行亚组分析。结果·共纳入28项诊断性试验，用诊断性试验准确性质量评价工具2（Diagnostic Accuracy Studies Tool Version 2，QUADAS-2）评价均属于中-高等质量研究，Spearman秩相关分析提示存在阈值效应，合并统计量后求得敏感度（Sen_合并）为0.80（95%CI 0.67~0.88），特异度（Spe_合并）为0.96（95%CI 0.92~0.98），阳性似然比（PLR_合并）为22.7（95%CI 9.4~55.2），阴性似然比（NLR_合并）为0.21（95%CI 0.12~0.36），诊断比数比（DOR_合并）为108（95%CI 31~374）。综合受试者工作特征（summary receiver operating characteristic，SROC）曲线的AUC为0.96（95%CI 0.94~0.98），提示cfDNA对BTC的诊断效能较高。亚组分析结果提示，选择不同的检测方式和样本来源的准确度和敏感度有所不同。结论·cfDNA检测对诊断BTC敏感度和特异度较高，适用于经影像学和常规肿瘤标志物初筛怀疑有恶性风险的患者，但检测方法和样本来源的选择仍需进一步开展面向更广泛人群的临床研究来进一步规范。

Objective ·To comprehensively evaluate the diagnostic accuracy of cell-free DNA (cfDNA) to biliary tract cancer (BTC), and provide a basis for better clinical application. Methods ·Clinical studies on the diagnostic value of cfDNA to BTC were collected by searching eight databases from inception to April 2023. The studies were selected according to the inclusion and exclusion criteria, and then data was extracted. The threshold effects were assessed with Spearman′s rank correlation analysis, and heterogeneity among the included studies was analyzed by using Cochran′s Q test and I² test. A bivariate mixed-effects model was fitted, and statistics such as overall sensitivity, specificity, and area under the curve (AUC) were calculated to determine the diagnostic performance. The subgroup analyses were carried out based on the study type, sample size, detection method, sample source, and diagnostic reference standard. Results ·A total of 28 diagnosis tests were included, all of which were evaluated as medium-high quality by using Diagnostic Accuracy Studies Tool Version 2 (QUADAS-2). The presence of threshold effects was found by using the Spearman rank correlation analysis. The pooled sensitivity was 0.80 (95%CI 0.67?0.88), and specificity was 0.96 (95%CI 0.92?0.98), positive likelihood ratio (PLR) was 22.7 (95%CI 9.4?55.2), negative likelihood ratio (NLR) was 0.21 (95%CI 0.12?0.36), and diagnostic odds ratio (DOR) was 108 (95%CI 31?374), respectively. The AUC of the summary receiver operating characteristic (SROC) curve was 0.96 (95%CI 0.94?0.98), demonstrating the high accuracy of cfDNA in the diagnosis of BTC. The results of subgroup analyses suggested that the accuracy and sensitivity of choosing different testing methods and sample sources varied. Conclusion ·The detection of cfDNA has high sensitivity and specificity in diagnosing BTC, and is suitable for the patients suspected to be malignant after screening with imaging tests and conventional tumor markers. However, the standardization and uniformity of detection methods and sample sources still need to be further standardized by conducting clinical studies on a wider population.