Distribution and Epidemiological Characteristics of Published Individual Patient Data Meta-Analyses

BackgroundIndividual patient data meta-analyses (IPDMAs) prevail as the gold standard in clinical evaluations. We investigated the distribution and epidemiological characteristics of published IPDMA articles.Methodology/Principal FindingsIPDMA articles were identified through comprehensive literature searches from PubMed, Embase, and Cochrane library. Two investigators independently conducted article identification, data classification and extraction. Data related to the article characteristics were collected and analyzed descriptively. A total of 829 IPDMA articles indexed until 9 August 2012 were identified. An average of 3.7 IPDMA articles was published per year. Malignant neoplasms (267 [32.2%]) and circulatory diseases (179 [21.6%]) were the most frequently occurring topics. On average, each IPDMA article included a median of 8 studies (Interquartile range, IQR 5 to 15) involving 2,563 patients (IQR 927 to 8,349). Among 829 IPDMA articles, 229 (27.6%) did not perform a systematic search to identify related studies. In total, 207 (25.0%) sought and included individual patient data (IPD) from the “grey literature”. Only 496 (59.8%) successfully obtained IPD from all identified studies.Conclusions/SignificanceThe number of IPDMA articles exhibited an increasing trend over the past few years and mainly focused on cancer and circulatory diseases. Our data indicated that literature searches, including grey literature and data availability were inconsistent among different IPDMA articles. Possible biases may arise. Thus, decision makers should not uncritically accept all IPDMAs.

背景：个体患者数据荟萃分析（Individual Patient Data Meta-Analysis, IPDMA）是临床评价领域公认的金标准。本研究旨在探讨已发表的IPDMA文章的分布特征与流行病学特点。
方法学与主要结果：研究通过对PubMed、Embase及Cochrane图书馆开展全面文献检索，筛选IPDMA文章。由两名研究者独立完成文献筛选、数据分类与提取工作。收集与文章特征相关的资料并进行描述性分析。截至2012年8月9日，共检索到829篇已收录的IPDMA文章，年均发表3.7篇。恶性肿瘤（267篇，占32.2%）与循环系统疾病（179篇，占21.6%）为最常见的研究主题。每篇IPDMA文章纳入的研究数量中位数为8项（四分位间距IQR：5~15），涉及患者数的中位数为2563例（IQR：927~8349）。在829篇IPDMA文章中，229篇（27.6%）未对相关研究开展系统检索。共计207篇（25.0%）尝试获取并纳入了“灰色文献”中的个体患者数据（Individual Patient Data, IPD）。仅496篇（59.8%）成功从所有筛选出的研究中获取了IPD。
结论与意义：近年间IPDMA文章的数量呈持续上升趋势，研究主题主要集中于肿瘤与循环系统疾病。本研究数据显示，不同IPDMA文章在文献检索（含灰色文献检索）及数据可及性方面存在显著不一致性，可能引入偏倚。因此，决策者不应不加甄别地全盘接受所有IPDMA研究结果。