提出隐私保护生存分析新方法,兼顾准确率与个体隐私安全。
A Differentially Private Kaplan-Meier Estimator for Privacy-Preserving Survival Analysis
- 引入时序拉普拉斯噪声与动态裁剪,按风险人数递减调整隐私预算。
- 在肺癌数据集上ε=10时RMSE低至0.04,逼近非私有估计结果。
- 高隐私预算(ε≥6)显著降低成员推断攻击成功率,适合医疗数据场景。
本文提出一种差分隐私的Kaplan-Meier估计方法,在保障个体隐私的同时实现高精度生存概率估计。该方法在临床等敏感数据应用中尤为重要,因传统估算可能泄露隐私。我们设计的新算法通过时序索引的拉普拉斯噪声、动态裁剪和光滑处理,在保持累积结构的前提下生成隐私保护的生存曲线。噪声随时间动态缩放,反映剩余风险人数减少带来的敏感度下降;动态裁剪与平滑有效抑制极端值与波动,维持曲线自然形态。在NCCTG肺癌数据集上的实验表明,该方法在不同隐私预算(ε)下均显著降低均方根误差(RMSE),当ε=10时,RMSE低至0.04,接近非私有估计。此外,成员推断攻击测试显示,ε≥6时关键点显著减少,尤其在高阈值处,大幅降低被攻击风险。结果验证了该方法在隐私与效用间取得良好平衡,推动了隐私保护生存分析的发展。
原文摘要 · Abstract (English)
This paper presents a differentially private approach to Kaplan-Meier estimation that achieves accurate survival probability estimates while safeguarding individual privacy. The Kaplan-Meier estimator is widely used in survival analysis to estimate survival functions over time, yet applying it to sensitive datasets, such as clinical records, risks revealing private information. To address this, we introduce a novel algorithm that applies time-indexed Laplace noise, dynamic clipping, and smoothing to produce a privacy-preserving survival curve while maintaining the cumulative structure of the Kaplan-Meier estimator. By scaling noise over time, the algorithm accounts for decreasing sensitivity as fewer individuals remain at risk, while dynamic clipping and smoothing prevent extreme values and reduce fluctuations, preserving the natural shape of the survival curve. Our results, evaluated on the NCCTG lung cancer dataset, show that the proposed method effectively lowers root mean squared error (RMSE) and enhances accuracy across privacy budgets ($ε$). At $ε= 10$, the algorithm achieves an RMSE as low as 0.04, closely approximating non-private estimates. Additionally, membership inference attacks reveal that higher $ε$ values (e.g., $ε\geq 6$) significantly reduce influential points, particularly at higher thresholds, lowering susceptibility to inference attacks. These findings confirm that our approach balances privacy and utility, advancing privacy-preserving survival analysis.
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