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关于临床试验的某些贝叶斯视角

Some Bayesian Perspectives on Clinical Trials

George Mason University(乔治梅森大学)

Alexandra Sokolova, Vadim Sokolov, Nick Polson

AI总结:

本文通过贝叶斯框架分析三个临床试验案例,提出两臂二项式试验的精确逆向归纳方法,改进样本量和功率平衡,适用于罕见病等患者节省场景。

摘要:

我们通过统一的贝叶斯框架分析了三个里程碑式的临床试验——ECMO、CALGB~49907和I-SPY~2。对于ECMO,治疗优越性的后验概率在考察的先验分布范围内是稳健的。对于CALGB,预测概率监控在633名而非1800名患者时停止入组。对于I-SPY~2,适应性补充将九个臂中的23个升级到III期。这些案例研究促使我们提出一种方法学贡献:两臂二项式试验的精确逆向归纳,其中Beta-Binomial共轭性在成功计数的整数格上产生闭式转换,无需四次方。Pólya-Gamma增强将此连接到协变量调整的逻辑回归。模拟揭示了一个根本性的张力:最优的贝叶斯设计将预期样本量减少到每臂14-26个(与替代方案的42-100相比),但功率显著降低。一种校准变体,嵌入声明阈值在终端效用中,提高了功率同时保持样本量节省;改变每阶段成本绘制了选择首选操作点的功率前沿,适合患者节省的场景,如罕见病和儿科。Pólya-Gamma拉普拉斯近似法通过精确计算验证(平均绝对误差低于0.01)。我们讨论了其对2026年FDA草案指南中贝叶斯方法的启示。

英文摘要:

We examine three landmark clinical trials -- ECMO, CALGB~49907, and I-SPY~2 -- through a unified Bayesian framework connecting prior specification, sequential adaptation, and decision-theoretic optimisation. For ECMO, the posterior probability of treatment superiority is robust across the range of priors examined. For CALGB, predictive probability monitoring stopped enrolment at 633 instead of 1800 patients. For I-SPY~2, adaptive enrichment graduated nine of 23 arms to Phase~III. These case studies motivate a methodological contribution: exact backward induction for two-arm binary trials, where Beta-Binomial conjugacy yields closed-form transitions on the integer lattice of success counts with no quadrature. A Pólya-Gamma augmentation bridges this to covariate-adjusted logistic regression. Simulation reveals a fundamental tension: the optimal Bayesian design reduces expected sample sizes to 14--26 per arm (versus 42--100 for alternatives) but with substantially lower power. A calibrated variant embedding the declaration threshold in the terminal utility improves power while maintaining sample-size savings; varying the per-stage cost traces a power frontier for selecting the preferred operating point, with suitability highest in patient-sparing contexts such as rare diseases and paediatrics. The Pólya-Gamma Laplace approximation is validated against exact calculations (mean absolute error below 0.01). We discuss implications for the 2026 FDA draft guidance on Bayesian methodology.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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