The problem of associating a continuous covariate, or biomarker, against a time-to-event outcome, is that it often requires categorisation of the covariate. This can lead to bias, loss of information and a poor representation of any underlying relationship. Here, two methods are proposed for estimating the effects of a continuous covariate on a time-to-event endpoint using weighted kernel estimators. The first method aims to estimate a density function for a time-to-event endpoint conditional on some covariate value whilst the second uses a joint density estimator. The results are visualisations in the form of surface plots that show the effects of a covariate without any need for categorisation. Both methods can aid interpretation and analysis of covariates against a time-to-event endpoint.
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http://dx.doi.org/10.1002/pst.2183 | DOI Listing |
Blood Adv
December 2024
U.S. Food and Drug Administration, Silver Spring, Maryland, United States.
Myelodysplastic syndromes/neoplasms (MDS) are heterogeneous stem cell malignancies characterized by poor prognosis and no curative therapies outside of allogeneic hematopoietic stem cell transplantation. Despite some recent approvals by the United States Food and Drug Administration (FDA), (e.g.
View Article and Find Full Text PDFJTCVS Open
December 2024
Department of Cardiovascular Surgery, Jefferson Health, Philadelphia, Pa.
Objective: To compare outcomes of aortic valve replacement (AVR) in patients with pure aortic stenosis (Pure AS) and those with pure aortic regurgitation (Pure AR) or mixed AS and AR (MAVD) in the COMMENCE trial.
Methods: Of 689 patients who underwent AVR in the COMMENCE trial, patients with moderate or severe AR with or without AS (Pure AR + MAVD; n = 135) or Pure AS (n = 323) were included. Inverse probability of treatment weighting Kaplan-Meier survival curves were used for time-to-event endpoints, and longitudinal changes in hemodynamics were evaluated using mixed-effects models.
JTCVS Open
December 2024
Department of Cardiothoracic Surgery, Friedrich-Schiller-University Jena, Jena, Germany.
Objectives: There is an ongoing debate whether percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) is the better choice for treatment of left main (LM) stenosis. We aimed to provide external validation for the recently reviewed guideline recommendations for invasive LM therapy by evaluating the impact of CABG or PCI on long-term survival from local reports of different regions in the world. We performed a systematic review and meta-analysis to address contemporary registry studies comparing PCI and CABG for patients with LM stenosis.
View Article and Find Full Text PDFAm J Epidemiol
December 2024
Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Target trial emulation (TTE) is a popular framework for observational studies based on electronic health records (EHR). A key component of this framework is determining the patient population eligible for inclusion in both a target trial of interest and its observational emulation. Missingness in variables that define eligibility criteria, however, presents a major challenge towards determining the eligible population when emulating a target trial with an observational study.
View Article and Find Full Text PDFBiom J
February 2025
Division of Biostatistics, German Cancer Research Center (DKFZ), Heidelberg, Germany.
The progression-free-survival ratio is a popular endpoint in oncology trials, which is frequently applied to evaluate the efficacy of molecularly targeted treatments in late-stage patients. Using elementary calculations and simulations, numerous shortcomings of the current methodology are pointed out. As a remedy to these shortcomings, an alternative methodology is proposed, using a marginal Cox model or a marginal accelerated failure time model for clustered time-to-event data.
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