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Select Contemporary Statistical Concepts in Heart Failure Clinical Trials: Insights From the Heart Failure Collaboratory.

Evolving statistical concepts and innovative trial designs for heart failure (HF) clinical trials seek to improve the conduct, efficiency, and likelihood of meaningful evidence generation crucial for advancing therapeutic development and optimizing patient care. HF trials with conventional statistical frameworks often require large sample sizes, long follow-up times, and high cost to generate sufficient evidence. Novel statistical methodologies would be of interest if they could address these issues while retaining or enhancing the clinical relevance and reliability of results. The HFC (Heart Failure Collaboratory), comprising clinical investigators, clinicians, statisticians, patients, government representatives, payors, and industry collaborators, leads efforts to improve HF research methodologies. HFC discussions have included statistical concepts such as the estimand framework, HR drift, and analytic methods, including the win ratio and restricted mean survival time, that have not been used frequently in HF trials. The estimand framework encourages precise definition and alignment of trial objectives with trial design. The win ratio method attempts to incorporate and prioritize multiple clinically meaningful outcomes by using a hierarchy of clinical importance. The restricted mean survival time provides an alternative to the HR as a measure of therapeutic effect by quantifying the mean time gained or lost during a fixed time after randomization. This paper provides a critical review of some evolving HF trial design methodologies and statistical concepts for the HF community as discussed within the HFC. Our goal is to foster collaboration among diverse stakeholders and advance the development of effective treatments and improve patient care outcomes.

Heart Failure

Estimands for Clinical Effectiveness of Risk-Reducing Early Salpingectomy in Women With High Risk of Ovarian Cancer.

IMPORTANCE: Risk-reducing early-salpingectomy (RRES) and delayed oophorectomy (DO) is a novel 2-stage alternative prevention strategy to risk-reducing salpingo-oophorectomy (RRSO) that avoids detrimental consequences of premature menopause. However, direct data on the clinical effectiveness for ovarian cancer (OC) risk reduction are lacking. OBJECTIVE: To explore how to define clinical effectiveness from prospective cohort studies using the estimand framework and sample size requirements. DESIGN, SETTING, AND PARTICIPANTS: In this comparative effectiveness research study, estimand and analysis options were considered to evaluate the clinical effectiveness of RRES with DO by extending the UK PROTECTOR cohort study, a multicenter, prospective, observational, national cohort study (N = 1250 recruited from January 1, 2019, to December 31, 2024) evaluating RRES and DO for OC surgical prevention. Participants were premenopausal women 30 years or older at increased OC risk due to BRCA1/BRCA2 pathogenic variants. Participants could choose RRES, RRSO, or no surgery at entry. Sample size requirements used initial data (eg, age and BRCA1/2 distribution) from PROTECTOR (analysis undertaken from January 1, 2024, to December 31, 2025). MAIN OUTCOMES AND MEASURES: Incidence of OC after (not at) RRES and before or at DO in women with normal histologic analysis findings at surgery. The proportion of cancers prevented was estimated as the completement of the observed (O) to expected (E; assuming no preventive effect of surgery) number of cancers detected (1 - O/E). RESULTS: Initial data were obtained from 889 women in PROTECTOR (overall mean [SD] age, 39 [5] years), with 255 (28.7%) choosing RRSO (mean [SD] age, 42 [4] years), 405 (45.5%) choosing RRES (mean [SD] age, 38 [4] years), and 229 (25.7%) choosing no surgery (mean [SD], 38 [5] years). The preferred estimand outcome was OC incidence after surgery (RRES or RRSO) with a "while on intervention" strategy to account for intercurrent events. The primary target measure was the proportion of cancers prevented for RRES vs no surgery with superiority testing. The secondary target measure was noninferiority of RRES vs RRSO. An estimated 1150 RRES participants with 8 to 10 years of follow-up would provide approximately 92% power to show that 20% or more of cancers are prevented using a 1-sample binomial test of the O:E risk (external reference) at the 5% level under a range of assumptions and at least the same power for a noninferiority margin for the proportion of cancers prevented by RRES of those prevented by RRSO. Estimands based on incidence ratios had an infeasible sample size. CONCLUSIONS AND RELEVANCE: In this comparative effectiveness study of UK BRCA carriers, the estimand differed from other ongoing clinical effectiveness studies of RRES and DO. Advantages include direct use of expected risk at baseline (unknown at design stage), easier interpretation across cohorts than absolute risk differences, and providing a feasible recruitment target for PROTECTOR to evaluate clinical effectiveness.

Humans

Causal Inference for Genomic Data with Multiple Heterogeneous Outcomes.

With the evolution of single-cell RNA sequencing techniques into a standard approach in genomics, it has become possible to conduct cohort-level causal inferences based on single-cell-level measurements. However, the individual gene expression levels of interest are not directly observable; instead, only repeated proxy measurements from each individual's cells are available, providing a derived outcome to estimate the underlying outcome for each of many genes. In this paper, we propose a generic semiparametric inference framework for doubly robust estimation with multiple derived outcomes, which also encompasses the usual setting of multiple outcomes when the response of each unit is available. To reliably quantify the causal effects of heterogeneous outcomes, we specialize the analysis to standardized average treatment effects and quantile treatment effects. Through this, we demonstrate the use of the semiparametric inferential results for doubly robust estimators derived from both Von Mises expansions and estimating equations. A multiple testing procedure based on Gaussian multiplier bootstrap is tailored for doubly robust estimators to control the false discovery exceedance rate. Applications in single-cell CRISPR perturbation analysis and individual-level differential expression analysis demonstrate the utility of the proposed methods and offer insights into the usage of different estimands for causal inference in genomics.

Derived outcomes

Human biopsy-defined ischemia-reperfusion injury-selective reperfusion signature prioritizes reperfusion-timed mitogen-activated protein kinase kinase inhibition after donation after circulatory death liver transplantation.

Early post-liver transplant ischemia-reperfusion injury (IRI) in donation after circulatory death grafts lacks therapies targeted to the immediate postreperfusion window, in part because generic reperfusion transcription obscures IRI-selective amplification. We analyzed paired prereperfusion/postreperfusion liver biopsies from 2 cohorts (GSE151648 and GSE87487) using a difference-in-differences interaction estimand (&#x394;&#x394; = [Post-Pre]IRI+ - [Post-Pre]IRI-) to define an IRI-selective early reperfusion program. Genome-wide &#x394;&#x394; effects were summarized using pathway-responsive genes, and pathway concordance was tested using permutation (B = 5000). The reproducible &#x394;&#x394; footprint highlighted epidermal growth factor receptor-mitogen-activated protein kinase signaling (Spearman &#x3c1; = 0.811; P = .001). Directional &#x394;&#x394; gene sets (interaction P < .05) were submitted to the L1000 characteristic direction signature search engine2; cross-cohort overlap identified 8 shared perturbagens, including 3 mitogen-activated protein kinase kinase (MEK)1/2 inhibitors. In a hepatic ischemia/reperfusion time course (GSE117915), epidermal growth factor receptor and mitogen-activated protein kinase activities increased within 0.5 hours of reperfusion, and transplant single-cell RNA sequencing (GSE189539) localized MEK/extracellular signal-regulated kinase pathway engagement predominantly to parenchymal cells. A representative MEK inhibitor, PD-0325901, reduced hepatocyte oxygen-glucose deprivation/reoxygenation injury and, when administered at reperfusion in a rat donation after circulatory death liver transplantation model (5-20 mg/kg), attenuated histologic and biochemical injury, apoptosis, and redox-inflammatory readouts and improved 7-day survival. Collectively, this biopsy-anchored &#x394;&#x394; interaction-phenotype framework, with cross-cohort concordance as a prespecified robustness gate, nominates reperfusion-timed MEK inhibition as a mechanism- and window-aligned strategy to blunt early post-liver transplant IRI.

difference-in-differences (time &#xd7; IRI interac