Chinese Evidence-based Medicine Center, West China Hospital, Sichuan University, Chengdu, China.
Department of Statistics, Florida State University, Tallahassee, Florida, USA.
Res Synth Methods. 2022 Sep;13(5):632-644. doi: 10.1002/jrsm.1587. Epub 2022 Jul 16.
In evidence-based practice, new topics generally only have a few studies available for synthesis. As a result, the evidence of such meta-analyses raised substantial concerns. We investigated the robustness of the evidence from these earliest studies. Real-world data from the Cochrane Database of Systematic Reviews (CDSR) were collected. We emulated meta-analyses with the earliest 1 to 10 studies through cumulative meta-analysis from eligible meta-analyses. The magnitude and the direction of meta-analyses with the earliest few studies were compared to the full meta-analyses. From the CDSR, we identified 20,227 meta-analyses of binary outcomes and 7683 meta-analyses of continuous outcomes. Under the tolerable difference of 20% on the magnitude of the effects, the convergence proportion ranged from 24.24% (earliest 1 study) to 77.45% (earliest 10 studies) for meta-analyses of few earliest studies with binary outcomes. For meta-analyses of continuous outcomes, the convergence proportion ranged from 13.86% to 56.52%. In terms of the direction of the effects, even when only three studies were available at the earliest stage, the majority had the same direction as full meta-analyses; Only 19% for binary outcomes and 12% for continuous outcomes changed the direction as further evidence accumulated. Synthesizing evidence from the earliest studies is feasible to support urgent decision-making, and in most cases, the decisions would be reasonable. Considering the potential uncertainties, it is essential to evaluate the confidence of the evidence of these meta-analyses and update the evidence when necessary.
在循证实践中，新的主题通常只有少数几项研究可供综合。因此，这些荟萃分析的证据引起了相当大的关注。我们调查了这些最早研究的证据的稳健性。从 Cochrane 系统评价数据库（CDSR）收集了真实世界的数据。我们通过合格荟萃分析的累积荟萃分析，模拟了最早的 1 到 10 项研究的荟萃分析。最早的少数几项研究的荟萃分析的幅度和方向与完整的荟萃分析进行了比较。从 CDSR 中，我们确定了 20227 项二项结局荟萃分析和 7683 项连续结局荟萃分析。在效应幅度可容忍差异为 20%的情况下，最早几项研究的荟萃分析中，二项结局荟萃分析的收敛比例范围为 24.24%（最早 1 项研究）至 77.45%（最早 10 项研究）。对于连续结局的荟萃分析，收敛比例范围为 13.86%至 56.52%。就效应的方向而言，即使在最早阶段只有三项研究可用，大多数研究的方向与完整的荟萃分析相同；只有 19%的二项结局和 12%的连续结局随着进一步证据的积累而改变了方向。从最早的研究中综合证据是可行的，可以支持紧急决策，在大多数情况下，这些决策是合理的。考虑到潜在的不确定性，评估这些荟萃分析证据的可信度并在必要时更新证据至关重要。
