Comparative Effectiveness of Aspirin Dosing in Cardiovascular Disease.

BACKGROUND: The appropriate dose of aspirin to lower the risk of death, myocardial infarction, and stroke and to minimize major bleeding in patients with established atherosclerotic cardiovascular disease is a subject of controversy. METHODS: Using an open-label, pragmatic design, we randomly assigned patients with established atherosclerotic cardiovascular disease to a strategy of 81 mg or 325 mg of aspirin per day. The primary effectiveness outcome was a composite of death from any cause, hospitalization for myocardial infarction, or hospitalization for stroke, assessed in a time-to-event analysis. The primary safety outcome was hospitalization for major bleeding, also assessed in a time-to-event analysis. RESULTS: A total of 15,076 patients were followed for a median of 26.2 months (interquartile range [IQR], 19.0 to 34.9). Before randomization, 13,537 (96.0% of those with available information on previous aspirin use) were already taking aspirin, and 85.3% of these patients were previously taking 81 mg of daily aspirin. Death, hospitalization for myocardial infarction, or hospitalization for stroke occurred in 590 patients (estimated percentage, 7.28%) in the 81-mg group and 569 patients (estimated percentage, 7.51%) in the 325-mg group (hazard ratio, 1.02; 95% confidence interval [CI], 0.91 to 1.14). Hospitalization for major bleeding occurred in 53 patients (estimated percentage, 0.63%) in the 81-mg group and 44 patients (estimated percentage, 0.60%) in the 325-mg group (hazard ratio, 1.18; 95% CI, 0.79 to 1.77). Patients assigned to 325 mg had a higher incidence of dose switching than those assigned to 81 mg (41.6% vs. 7.1%) and fewer median days of exposure to the assigned dose (434 days [IQR, 139 to 737] vs. 650 days [IQR, 415 to 922]). CONCLUSIONS: In this pragmatic trial involving patients with established cardiovascular disease, there was substantial dose switching to 81 mg of daily aspirin and no significant differences in cardiovascular events or major bleeding between patients assigned to 81 mg and those assigned to 325 mg of aspirin daily. (Funded by the Patient-Centered Outcomes Research Institute; ADAPTABLE ClinicalTrials.gov number, NCT02697916.).

Principal stratification analysis of noncompliance with time-to-event outcomes.

Post-randomization events, also known as intercurrent events, such as treatment noncompliance and censoring due to a terminal event, are common in clinical trials. Principal stratification is a framework for causal inference in the presence of intercurrent events. The existing literature on principal stratification lacks generally applicable and accessible methods for time-to-event outcomes. In this paper, we focus on the noncompliance setting. We specify 2 causal estimands for time-to-event outcomes in principal stratification and provide a nonparametric identification formula. For estimation, we adopt the latent mixture modeling approach and illustrate the general strategy with a mixture of Bayesian parametric Weibull-Cox proportional hazards model for the outcome. We utilize the Stan programming language to obtain automatic posterior sampling of the model parameters. We provide analytical forms of the causal estimands as functions of the model parameters and an alternative numerical method when analytical forms are not available. We apply the proposed method to the ADAPTABLE (Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness) trial to evaluate the causal effect of taking 81 versus 325 mg aspirin on the risk of major adverse cardiovascular events. We develop the corresponding R package PStrata.

Multiply robust estimation of principal causal effects with noncompliance and survival outcomes.

Treatment noncompliance and censoring are two common complications in clinical trials. Motivated by the ADAPTABLE pragmatic clinical trial, we develop methods for assessing treatment effects in the presence of treatment noncompliance with a right-censored survival outcome. We classify the participants into principal strata, defined by their joint potential compliance status under treatment and control. We propose a multiply robust estimator for the causal effects on the survival probability scale within each principal stratum. This estimator is consistent even if one, sometimes two, of the four working models-on the treatment assignment, the principal strata, censoring, and the outcome-is misspecified. A sensitivity analysis strategy is developed to address violations of key identification assumptions, the principal ignorability and monotonicity. We apply the proposed approach to the ADAPTABLE trial to study the causal effect of taking low- versus high-dosage aspirin on all-cause mortality and hospitalization from cardiovascular diseases.

External Control Arms in Idiopathic Pulmonary Fibrosis Using Clinical Trial and Real-World Data Sources.

Rationale: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease for which novel therapies are needed. External controls (ECs) could enhance IPF trial efficiency, but the direct comparability of ECs versus concurrent controls is unknown. Objectives: To develop IPF ECs by fit-for-purpose data standards to historical randomized clinical trial (RCT), multicenter registry (Pulmonary Fibrosis Foundation Patient Registry), and electronic health record (EHR) data and to evaluate endpoint comparability among ECs and the phase II RCT of BMS-986020. Methods: After data curation, the rate of change in FVC from baseline to 26 weeks among participants receiving BMS-986020 600 mg twice daily was compared with the BMS-placebo arm and ECs using mixed-effects models with inverse probability weights. Measurements and Main Results: At 26 weeks, the rates of change in FVC were -32.71 ml for BMS-986020 and -130.09 ml for BMS-placebo (difference, 97.4 ml; 95% confidence interval [CI], 24.6-170.2), replicating the original BMS-986020 RCT. RCT ECs showed treatment effect point estimates within the 95% CI of the original BMS-986020 RCT. Pulmonary Fibrosis Foundation Patient Registry ECs and EHR ECs experienced a slower rate of FVC decline compared with the BMS-placebo arm, resulting in treatment-effect point estimates outside of the 95% CI of the original BMS-986020 RCT. Conclusions: IPF ECs generated from historical RCT placebo arms result in comparable primary treatment effects to that of the original clinical trial, whereas ECs from real-world data sources, including registry or EHR data, do not. RCT ECs may serve as a potentially useful supplement to future IPF RCTs.

Electronic health record characterization and outcomes of heart failure with preserved ejection fraction.

BACKGROUND: Electronic health record (EHR)-based identification of heart failure with preserved ejection fraction (HFpEF) in the clinical setting may facilitate screening for clinical trials by improving the understanding of its epidemiology and outcomes; yet, previous data have yielded variable results. We sought to characterize groups identified with HFpEF by different EHR screening strategies and their associated long-term outcomes across a large and diverse population. METHODS: We retrospectively analyzed 116,499 consecutive patients from an academic referral center who underwent echocardiography, and 9,263 patients who underwent echocardiography within 6 months of right heart catheterization (RHC), between 2008 and 2018. EHR-based screening strategies identified patients with HFpEF using 1) International Classification of Diseases (ICD)-9/10 codes, 2) H2FpEF score ≥6 and ejection fraction (EF) ≥50%, or 3) RHC wedge pressure ≥15 mmHg and EF ≥50%, when available. Primary outcomes were 1) cumulative incident heart failure hospitalization (HFH), and 2) death, over 10 years. RESULTS: There were 33,461 (29%) patients who met either ICD or H2FpEF-HFpEF definition, of whom 5,310 (16%) met both criteria. Compared to ICD-HFpEF, patients with H2FpEF-HFpEF were more likely older (median age 72 vs 67), White (78% vs 64%), and had atrial fibrillation (97% vs 41%). Among those also with RHC, 6,353 (69%) patients met any HFpEF criteria, of whom only 783 (12%) satisfied all three criteria. Female sex was more common among RHC-HFpEF (55%) compared to other methods (H2FpEF-HFpEF, 47%; ICD-HFpEF, 43%). Atrial fibrillation was substantially higher among HFpEF identified by the H2FpEF score (97%) compared to other methods (49% for ICD and 47% for RHC). Across HFpEF screening methods, 10-year cumulative incidence rates for HFH was 32% to 45% for echocardiography only and 43% to 52% for echocardiography and RHC populations; 10-year risk of death was 54% to 56% for echocardiography only and 52% to 57% for echocardiography and RHC populations. CONCLUSIONS: Different EHR-based HFpEF definitions identified cohorts with modest overlap and varying baseline characteristics. Yet, long-term risk for HFH and death were similarly high for cohorts identified among both populations undergoing echocardiography only or echocardiography and RHC. These data aid in identifying relevant subgroups in clinical trials of HFpEF.

Comparison of the effectiveness and safety of 2 aspirin doses in secondary prevention of cardiovascular outcomes in patients with chronic kidney disease: A subgroup analysis of ADAPTABLE.

BACKGROUND: Among patients with established cardiovascular disease, the ADAPTABLE trial found no significant differences in cardiovascular events and bleeding rates between 81 mg and 325 mg of aspirin (ASA) daily. In this secondary analysis from the ADAPTABLE trial, we studied the effectiveness and safety of ASA dosing in patients with a history of chronic kidney disease (CKD). METHODS: ADAPTABLE participants were stratified based on the presence or absence of CKD, defined using ICD-9/10-CM codes. Within the CKD group, we compared outcomes between patients taking ASA 81 mg and 325 mg. The primary effectiveness outcome was defined as a composite of all cause death, myocardial infarction, or stroke and the primary safety outcome was hospitalization for major bleeding. Adjusted Cox proportional hazard models were utilized to report differences between the groups. RESULTS: After excluding 414 (2.7%) patients due to missing medical history, a total of 14,662 patients were included from the ADAPTABLE cohort, of whom 2,648 (18%) patients had CKD. Patients with CKD were older (median age 69.4 vs 67.1 years; P < .0001) and less likely to be white (71.5% vs 81.7%; P < .0001) when compared to those without CKD. At a median follow-up of 26.2 months, CKD was associated with an increased risk of both the primary effectiveness outcome (adjusted HR 1.79 [1.57, 2.05] P < .001 and the primary safety outcome (adjusted HR 4.64 (2.98, 7.21), P < .001 and P < .05, respectively) regardless of ASA dose. There was no significant difference in effectiveness (adjusted HR 1.01 95% CI 0.82, 1.23; P = .95) or safety (adjusted HR 0.93; 95% CI 0.52, 1.64; P = .79) between ASA groups. CONCLUSIONS: Patients with CKD were more likely than those without CKD to have adverse cardiovascular events or death and were also more likely to have major bleeding requiring hospitalization. However, there was no association between ASA dose and study outcomes among these patients with CKD.

Outcomes among patients with peripheral artery disease in the Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness (ADAPTABLE) study.

BACKGROUND: We aimed to understand the effects of aspirin dose on outcomes in patients with peripheral artery disease (PAD) as well as their participation in a pragmatic randomized controlled trial. METHODS: In a subanalysis of the Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness (ADAPTABLE) study, we compared aspirin doses (81 vs 325 mg) among participants with PAD and study participation metrics in patients with and without PAD. The primary outcome composite was all-cause mortality, nonfatal myocardial infarction, and nonfatal stroke. RESULTS: Among 14,662 participants enrolled in ADAPTABLE with PAD status available, 3493 (23.8%) had PAD. Participants with PAD were more likely to experience the primary composite (13.76% vs 5.31%, p < 0.001), all-cause mortality (7.55% vs 3.01%, p < 0.001), myocardial infarction (5.71% vs 2.09%, p < 0.001), stroke (2.45% vs 0.86%, p < 0.001), and major bleeding (1.19% vs 0.44%, p < 0.001). A higher aspirin dose did not reduce the primary outcome in patients with PAD (13.68% vs 13.84% in 81 mg and 325 mg groups; OR 1.05, 95% CI 0.88-1.25). Participants with PAD were less likely to enroll via email (33.0% vs 41.9%, p < 0.0001), less likely to choose internet follow-up (79.2% vs 89.5%, p < 0.0001), and were more likely to change their aspirin doses (39.7% vs 30.7%, p < 0.0001). CONCLUSIONS: ADAPTABLE participants with PAD did not benefit from a higher dose of aspirin and participated in the study differently from those without PAD. These results reinforce the need for additional PAD-specific research and suggest that different trial strategies may be needed for optimal engagement of patients with PAD. (ClinicalTrials.gov Identifier: NCT02697916).

Looking for opportunities to co-enroll: The DISCOVERY study experience.

BACKGROUND: Conducting high-quality stroke trials is complex and costly. Often these trials compete for the attention of researchers and the availability of patients. Enrolling patients in more than one study concurrently has the potential to accelerate recruitment into individual studies. DISCOVERY is a multicenter, inception cohort study of cognitive impairment and dementia following ischemic or hemorrhagic stroke. At the request of site investigators, a DISCOVERY committee reviews individual studies for approval of possible concurrent co-enrollment into DISCOVERY. The purpose of this report is to summarize the characteristics and outcomes of studies reviewed by committee for possible co-enrollment. METHODS: This analysis covers studies reviewed from 07/01/2020 to 04/26/2022 by the Site Management Committee (SMC) of the DISCOVERY Recruitment and Retention Core. Characterization of each study included study type, number and length of follow-up visits, and whether there were protocol-required blood draws, brain imaging studies, or cognitive tests. Studies were scored for patient burden and scientific overlap with Discovery. The primary outcome was SMC approval to co-enroll. RESULTS: 59 studies were reviewed, and 69.5% (n = 41, 21 clinical trials; 20 observational studies) were found by the SMC to be appropriate for co-enrollment. Higher patient burden and greater scientific overlap with DISCOVERY reduced the rates of approval for co-enrollment. CONCLUSION: A large number of diverse stroke studies are being run concurrently across the DISCOVERY study network, however, about two-thirds of the studies were considered appropriate for consideration of co-enrollment. Future studies should study how co-enrollment might improve trial network efficiency.

Cognitive Impairment and Dementia After Stroke: Design and Rationale for the DISCOVERY Study.

Stroke is a leading cause of the adult disability epidemic in the United States, with a major contribution from poststroke cognitive impairment and dementia (PSCID), the rates of which are disproportionally high among the health disparity populations. Despite the PSCID's overwhelming impact on public health, a knowledge gap exists with regard to the complex interaction between the acute stroke event and highly prevalent preexisting brain pathology related to cerebrovascular and Alzheimer disease or related dementia. Understanding the factors that modulate PSCID risk in relation to index stroke event is critically important for developing personalized prognostication of PSCID, targeted interventions to prevent it, and for informing future clinical trial design. The DISCOVERY study (Determinants of Incident Stroke Cognitive Outcomes and Vascular Effects on Recovery), a collaborative network of thirty clinical performance clinical sites with access to acute stroke populations and the expertise and capacity for systematic assessment of PSCID will address this critical challenge. DISCOVERY is a prospective, multicenter, observational, nested-cohort study of 8000 nondemented ischemic and hemorrhagic stroke patients enrolled at the time of index stroke and followed for a minimum of 2 years, with serial cognitive evaluations and assessments of functional outcome, with subsets undergoing research magnetic resonance imaging and positron emission tomography and comprehensive genetic/genomic and fluid biomarker testing. The overall scientific objective of this study is to elucidate mechanisms of brain resilience and susceptibility to PSCID in diverse US populations based on complex interplay between life-course exposure to multiple vascular risk factors, preexisting burden of microvascular and neurodegenerative pathology, the effect of strategic acute stroke lesions, and the mediating effect of genomic and epigenomic variation.

At-home testing to mitigate community transmission of SARS-CoV-2: protocol for a public health intervention with a nested prospective cohort study.

BACKGROUND: The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve as a global health crisis. Although highly effective vaccines have been developed, non-pharmaceutical interventions remain critical to controlling disease transmission. One such intervention-rapid, at-home antigen self-testing-can ease the burden associated with facility-based testing programs and improve testing access in high-risk communities. However, its impact on SARS-CoV-2 community transmission has yet to be definitively evaluated, and the socio-behavioral aspects of testing in underserved populations remain unknown. METHODS: As part of the Rapid Acceleration of Diagnostics-Underserved Populations (RADx-UP) program funded by the National Institutes of Health, we are implementing a public health intervention titled "Say Yes! COVID Test" (SYCT) involving at-home self-testing using a SARS-CoV-2 rapid antigen assay in North Carolina (Greenville, Pitt County) and Tennessee (Chattanooga City, Hamilton County). The intervention is supported by a multifaceted communication and community engagement strategy to ensure widespread awareness and uptake, particularly in marginalized communities. Participants receive test kits either through online orders or via local community distribution partners. To assess the impact of this intervention on SARS-CoV-2 transmission, we will conduct a non-randomized, ecological study using community-level outcomes. Specifically, we will evaluate trends in SARS-CoV-2 cases and hospitalizations, SARS-CoV-2 viral load in wastewater, and population mobility in each community before, during, and after the SYCT intervention. Individuals who choose to participate in SYCT will also have the option to enroll in an embedded prospective cohort substudy gathering participant-level data to evaluate behavioral determinants of at-home self-testing and socio-behavioral mechanisms of SARS-CoV-2 community transmission. DISCUSSION: This is the first large-scale, public health intervention implementing rapid, at-home SARS-CoV-2 self-testing in the United States. The program consists of a novel combination of an at-home testing program, a broad communications and community engagement strategy, an ecological study to assess impact, and a research substudy of the behavioral aspects of testing. The findings from the SYCT project will provide insights into innovative methods to mitigate viral transmission, advance the science of public health communications and community engagement, and evaluate emerging, novel assessments of community transmission of disease.