{"title":"Unobserved heterogeneity in threshold regression based on the hitting times of a reflected Brownian motion for recurrent hypoglycemia.","authors":"Yingfa Xie, Haoda Fu, Yuan Huang, Jun Yan","doi":"10.1007/s10985-026-09717-x","DOIUrl":"10.1007/s10985-026-09717-x","url":null,"abstract":"<p><p>Analyses of recurrent hypoglycemia are critical for effective treatment management in diabetic patients. Typically, within-subject dependency in such analyses is captured through subject-level frailty. Recent research has modeled recurrent hypoglycemia using the first hitting times of a reflected Brownian motion. A close examination of this approach reveals that it does not adequately account for varying frailties among individuals, which indicate notable heterogeneity. To address this gap, we propose a finite mixture model of the first hitting time distribution of the reflected Brownian motion. This model allows for component-specific regression coefficients and frailty parameters, providing nuanced insights into how risk factors differently affect patient subgroups. We employ a Bayesian framework for inference, utilizing Markov chain Monte Carlo for estimation. Model selection is conducted using the Deviance Information Criterion and the Logarithm of the Pseudo-Marginal Likelihood. The effectiveness of these criteria is assessed through simulation studies. Application to recurrent hypoglycemia modeling revealed two subgroups with different risk profiles, as reflected in their volatilities. Bayesian model comparison criteria favor the model with component-specific regression coefficients for volatilities. The subgroup with lower volatility exhibits a larger variance and, hence, a greater level of heterogeneity.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148145269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Variable selection with broken adaptive ridge regression for interval-censored competing risks data.","authors":"Fatemeh Mahmoudi, Chenxi Li, Kaida Cai, Xuewen Lu","doi":"10.1007/s10985-026-09711-3","DOIUrl":"10.1007/s10985-026-09711-3","url":null,"abstract":"<p><p>Competing risks data refer to situations in which the occurrence of one event precludes the occurrence of other events, resulting in multiple mutually exclusive events. This data type is commonly encountered in medical research and clinical trials, where it is used to explore the interplay among events and to inform decision-making in fields such as healthcare and epidemiology. We develop a penalized variable selection procedure to handle such complex data in an interval-censored setting. We consider a broad class of semiparametric transformation regression models, including popular models such as proportional and non-proportional hazards models. To promote sparsity and select variables specific to each event, we employ the broken adaptive ridge (BAR) penalty. This approach allows us to simultaneously select important risk factors and estimate their effects for each event under investigation. We establish the oracle property of the BAR procedure and evaluate its performance through simulation studies. The proposed method is applied to a real-life HIV cohort dataset, further validating its applicability in practice.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148058006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Training-set conditionally valid prediction sets with right-censored data.","authors":"Wenwen Si, Hongxiang Qiu","doi":"10.1007/s10985-026-09697-y","DOIUrl":"10.1007/s10985-026-09697-y","url":null,"abstract":"<p><p>Uncertainty quantification of prediction models through prediction sets is increasingly popular and successful, but most existing methods rely on directly observing the outcome and do not appropriately handle censored outcomes, such as time-to-event outcomes. Candès et al. (2023) and Gui et al. (2024) have introduced distribution-free conformal prediction methods that construct predictive intervals for right-censored outcomes with marginal coverage guarantees. However, these methods typically assume a restrictive Type I censoring framework, in which censoring times are all observed. In this paper, we leverage a semiparametric one-step estimation framework and propose a novel approach for constructing predictive lower bounds on survival times with training-set conditional validity under right-censoring, where censoring times may be unobserved when the survival time is observed. With slight modification, our method can also provide predictive lower bounds with marginal guarantees. Through extensive simulations and a real-world application dataset tracking users' active times on a mobile application, we demonstrate the effectiveness and practicality of our approach. Compared to existing methods, our technique shows superior efficiency and robustness to model misspecifications, representing a significant advancement in the toolbox for reliable machine learning for time-to-event outcomes.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13194291/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147984142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adrián Lago, Juan Carlos Pardo-Fernández, Jacobo de Uña-Álvarez
{"title":"Kolmogorov-Smirnov and Cramér-von Mises tests for the k-sample problem with left-truncated and right-censored data.","authors":"Adrián Lago, Juan Carlos Pardo-Fernández, Jacobo de Uña-Álvarez","doi":"10.1007/s10985-026-09713-1","DOIUrl":"10.1007/s10985-026-09713-1","url":null,"abstract":"<p><p>k-Sample versions of the Kolmogorov-Smirnov and Cramér-von Mises tests are proposed for data subject to left truncation and right censoring. Their asymptotic behaviour is studied and a bootstrap resampling plan is proposed to approximate the null distribution of the new tests. The performance of the tests with finite sample sizes is investigated in a simulation study, where the classical log-rank test is also considered. An illustration with a real dataset regarding unemployment times is discussed.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13179922/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147960335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Gradient boosting-based discrete failure time model for selecting time-varying effects and interactions.","authors":"Lingfeng Luo, Kevin He, Jeremy M G Taylor","doi":"10.1007/s10985-026-09710-4","DOIUrl":"10.1007/s10985-026-09710-4","url":null,"abstract":"<p><p>Analyzing survival data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program offers invaluable insight to guide cancer management. In these data the event times are recorded in units of months. In such datasets, it can be important to consider the selection of covariates, distinguish between time-varying and time-independent effects, and capture important interaction terms. However, variable selection is difficult to combine with the differentiation between time-varying and time-independent effects. Moreover, accurately selecting interaction terms is more challenging because of the hierarchy restriction that an interaction term should only enter a model if one or both associated main effects are also included. To resolve these issues, we develop a coordinate ascent-based gradient boosting procedure for discrete failure time models. This approach achieves variable selection in high-dimensional settings, differentiates between time-varying and time-independent variables, and selects important interaction terms under hierarchy restrictions. Traditional boosting stopping criteria are ad hoc, while preferable information-criteria-based rules necessitate defining degrees of freedom, a challenge in survival models. Our approach provides well-defined degrees of freedom and offers information-criteria-based stopping rules. Simulation studies show the proposed method achieves good selection performance. We apply the proposed method to SEER melanoma cancer data and select important risk factors, distinguish between time-varying and time-dependent effects and detect important two-way interactions.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13167897/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147935000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johannes Piller, Léa Orsini, Simon Wiegrebe, Sophie Hanna Langbein, Lukas Burk, John Zobolas, Philip Studener, Markus Goeswein, Andreas Bender
{"title":"Reduction techniques for survival analysis.","authors":"Johannes Piller, Léa Orsini, Simon Wiegrebe, Sophie Hanna Langbein, Lukas Burk, John Zobolas, Philip Studener, Markus Goeswein, Andreas Bender","doi":"10.1007/s10985-026-09714-0","DOIUrl":"10.1007/s10985-026-09714-0","url":null,"abstract":"<p><p>In this work, we discuss what we refer to as reduction techniques for survival analysis, that is, techniques that \"reduce\" a survival task to a more common regression or classification task, without ignoring the specifics of survival data. Such techniques particularly facilitate machine learning-based survival analysis, as they allow for applying standard tools from machine and deep learning to many survival tasks without requiring custom learners. We provide an overview of different reduction techniques and discuss their respective strengths and weaknesses. We also provide a principled implementation of some of these reductions, such that they are directly available within standard machine learning workflows. We illustrate each reduction using dedicated examples and perform a benchmark analysis that compares their predictive performance to established machine learning methods for survival analysis.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13216100/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148044539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Todd A MacKenzie, Pablo Martínez-Camblor, Haobin Chen, Jesse A Columbo, A James O'Malley
{"title":"Instrumental variable estimation of a hazard ratio for treatment with a waiting time without specifying its dependence on unmeasured confounders: application to a procedural registry.","authors":"Todd A MacKenzie, Pablo Martínez-Camblor, Haobin Chen, Jesse A Columbo, A James O'Malley","doi":"10.1007/s10985-026-09706-0","DOIUrl":"10.1007/s10985-026-09706-0","url":null,"abstract":"<p><p>The timing of an intervention such as surgery may happen sometime after treatment inception (e.g., diagnosis date) due to being put on a wait-list for treatment or being scheduled for treatment at a later time. If interest lies in the change in risk upon receiving the intervention, a Cox model with a time-dependent exposure may be employed. However, if there exists unmeasured confounding, maximum partial likelihood estimators of the hazard ratio are biased. An instrumental variable is a cause of the exposure of interest but not of the outcome except through the exposure. We propose a new framework involving potential outcomes for each possible waiting time, and derive an estimating equation for the hazard ratio of a treatment with a time-dependent start using an instrumental variable without making any assumptions about the form of involvement of unmeasured confounders. We conducted simulations to evaluate bias of our hazard ratio estimator. We illustrate the approach using two examples: First, we analyzed a procedural registry for which instrumental variable based estimators may be the only unbiased approach. Second, we demonstrate causal hazard ratio estimation for a randomized trial with time-dependent treatment initiation.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13128713/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147787147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A dependent and censored first hitting-time model with compound Poisson processes.","authors":"Mikael Escobar-Bach, Alexandre Popier, Malo Sahin","doi":"10.1007/s10985-026-09705-1","DOIUrl":"10.1007/s10985-026-09705-1","url":null,"abstract":"<p><p>We consider a bivariate first hitting-time model in which durations are the crossing times of dependent compound Poisson processes with fixed thresholds. The identifiability of the model is discussed, and likelihood estimators of the model parameters are proposed. We obtain the asymptotic properties of the estimators and underline their finite sample performance with a simulation study on synthetic data. The practical applicability of our approach is demonstrated by an application using data from patients suffering from mushroom poisoning.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13121319/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147787094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The semi-competing risk problem revisited.","authors":"Ross L Prentice, Aaron K Aragaki","doi":"10.1007/s10985-026-09709-x","DOIUrl":"10.1007/s10985-026-09709-x","url":null,"abstract":"<p><p>Clinical trials and cohort studies often aim to assess treatment effects or exposure associations in relation to the risk of one or more diseases, with death of the study participant as a competing risk. If the diseases under study are major health concerns, it may not be appropriate to assume that death acts as an independent source of right-censoring. When this occurs, a summary of treatment or exposure influences should consider disease incidence and death jointly. Here we consider some modeling approaches to doing so, starting with type-specific (cause-specific) hazard functions. We also model marginal hazard rates for disease-free survival and death, along with their dual outcome hazard functions, with emphasis on Cox models for each hazard function. Furthermore, a simple hazard ratio summary statistic is proposed for covariate effects on disease incidence and death jointly. Analyses of data from the Women's Health Initiative hormone therapy trials provide illustration.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147787394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Q-learning via deep learning-based Buckley-James method for non-linear censored data.","authors":"Jeongjin Lee, Jong-Min Kim","doi":"10.1007/s10985-026-09707-z","DOIUrl":"10.1007/s10985-026-09707-z","url":null,"abstract":"<p><p>In healthcare, personalized treatment strategies are vital for improving patient outcomes, especially under right-censored survival data. We propose Dynamic Deep Buckley-James Q-Learning, a novel counterfactual Q-learning algorithm that integrates deep learning with the Buckley-James method to simultaneously address censoring and nonlinear modeling challenges. By explicitly capturing complex, nonlinear interactions between covariates and treatment effects, the algorithm robustly estimates optimal dynamic treatment regimes. Leveraging a counterfactual framework, we define and estimate potential survival outcomes under hypothetical treatment sequences, enabling unbiased Q-function estimation even in the presence of time-dependent covariates and right censoring. The algorithm maximizes the expected imputed survival reward under these counterfactual scenarios. Simulation studies and real-world data analysis demonstrate its superior performance in predictive accuracy and treatment decision-making, offering a powerful framework for individualized care in complex clinical settings.</p>","PeriodicalId":49908,"journal":{"name":"Lifetime Data Analysis","volume":"32 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147624462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}