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Importance: Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of morbidity and mortality in the US. Although aspirin is recommended for secondary prevention of ASCVD, there was no difference in safety and effectiveness of aspirin dosed daily at 81 mg or 325 mg in the ADAPTABLE (Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness) randomized clinical trial. However, it is unknown whether differences by sex exist in the safety and effectiveness of the different aspirin doses., Objective: To evaluate sex-specific differences in the safety and effectiveness of 2 aspirin doses in the ADAPTAPLE trial., Design, Setting, and Participants: The ADAPTABLE study was an open-label, pragmatic, randomized clinical trial that randomly assigned participants with chronic, stable ASCVD to 81 mg vs 325 mg of aspirin daily. Using Cox proportional-hazard models, male and female participants were compared for outcomes. In addition, it was assessed whether sex was an effect modifier in the association between aspirin dose and outcomes. The ADAPTABLE trial was conducted at 40 medical centers and 1 health plan. Eligible patients were 18 years and older and had established ASCVD. Study data were analyzed from December 2021 to March 2024., Interventions: Patients received 81 mg or 325 mg of aspirin daily for the secondary prevention of ASCVD., Main Outcomes and Measures: The primary effectiveness outcomes included all-cause death and hospitalization for myocardial infarction (MI) or stroke. The primary safety outcome was hospitalization for major bleeding requiring transfusion., Results: A total of 15 076 patients (median [IQR] age, 67.6 [60.7-73.6] years; 10 352 male [68.7%]) were followed up for a median (IQR) of 26.2 (19.0-34.9) months. Overall, 4724 (31.3%) were female, and 2307 of the female participants (48.8%) received aspirin 81 mg. Compared with males, female participants were younger (median [IQR] age, 66.3 [59.4-72.6] years vs 68.2 (61.4-73.9) years, less likely to self-report White race (3426 [72.5%] vs 8564 [82.7%]), more likely to smoke (564 [12.9%] vs 818 [8.4%]), and more likely to have a history of peripheral arterial disease (1179 [25.7%] vs 2314 [23.0%]). The primary effectiveness outcome of all-cause death and hospitalization for MI or stroke occurred in 379 female participants (8.1%) and 780 male participants (7.1%). There was no significant interaction by sex for the primary effectiveness end point between the 2 aspirin doses (female adjusted hazard ratio [aHR], 1.01; 95% CI, 0.82-1.26 and male aHR, 1.06; 95% CI, 0.91-1.23; P interaction term for sex = .74). During the trial, female participants had fewer revascularization procedures (237 [5.0%] vs 680 [6.6%]; aHR, 0.79; 95% CI, 0.68-0.92; P = .002) but had a higher risk of hospitalization for stroke (aHR, 1.72; 95% CI, 1.27-2.33; P < .001). Among female participants, there was a slightly higher rate of bleeding in the 81-mg aspirin cohort compared with the 325-mg cohort (20 [0.83%] vs 13 [0.52%]; aHR, 2.21; 95% CI, 1.04-4.70; P interaction term for sex = .07). There were no significant differences between female and male participants regarding aspirin dose adherence., Conclusions and Relevance: In this secondary analysis of the ADAPTABLE trial, there were no significant sex-specific differences in the effectiveness and safety of 2 aspirin doses for secondary prevention of ASCVD events., Trial Registration: ClinicalTrials.gov Identifier: NCT02697916.

Objectives: To evaluate whether the effectiveness and safety of low (81 mg daily) versus high-dose (325 mg daily) aspirin is consistent across races among patients with established atherosclerotic cardiovascular disease (ASCVD)., Design: A secondary analysis of the randomised controlled trial ADAPTABLE was performed., Setting: The study was conducted in 40 centres and one health plan participating in the National Patient-Centred Clinical Research Network (PCORnet) in the USA., Participants: Among 15 076 participants with established ASCVD, 14 096 had self-reported race available and were included in the analysis. Participants were divided according to self-reported race as Black (n=1311, 9.3%), White (n=11 990, 85.1%) or other race (n=795, 5.6%)., Interventions: Participants were randomised to open-label daily aspirin doses of 81 mg versus 325 mg in a 1:1 ratio for a median of 26.2 months., Primary and Secondary Outcomes Measures: The primary effectiveness endpoint was a composite of death from any cause, hospitalisation for myocardial infarction or hospitalisation for stroke. The primary safety endpoint was hospitalisation for bleeding requiring blood product transfusion., Results: Estimated cumulative incidence of the primary effectiveness endpoint at median follow-up with the 81 mg and the 325 mg daily doses were 6.70% and 7.12% in White participants (adjusted HR: 1.00 [95% CI: 0.88 to 1.15]); 12.27% and 10.69% in Black participants (adjusted HR: 1.40 [95% CI: 1.02 to 1.93]); and 6.88% and 7.69% in other participants (adjusted HR: 0.86 [95% CI: 0.54 to 1.39]) (p-interaction=0.12), respectively. There was no significant interaction between self-reported race and assigned aspirin dose regarding the secondary effectiveness and the primary safety endpoints., Conclusion: Race is not an effect modifier on the impact of aspirin dosing on effectiveness and safety in patients with established ASCVD. In clinical practice, treatment decisions regarding aspirin dose in secondary prevention of ASCVD should not be influenced by race., Trial Registration Number: NCT02697916., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: ADAPTABLE (Aspirin Dosing: A Patient-centric Trial Assessing Benefits and Long-Term Effectiveness) is a pragmatic clinical trial examining high-dose versus low-dose aspirin among patients with cardiovascular disease. ADAPTABLE is leveraging novel approaches for clinical trial conduct to expedite study completion and reduce costs. One pivotal aspect of the trial conduct is maximizing clinician engagement., Methods/results: Clinician engagement can be diminished by barriers including time limitations, insufficient research infrastructure, lack of research training, inadequate compensation for research activities, and clinician beliefs. We used several key approaches to boost clinician engagement such as empowering clinician champions, including a variety of clinicians, nurses and advanced practice providers, periodic newsletters and coordinated team celebrations, and deploying novel technological solutions. Specifically, some centers generated electronic health records-based best practice advisories and research dashboards. Future large pragmatic trials will benefit from standardization of the various clinician engagement strategies especially studies leveraging electronic health records-based approaches like research dashboards. Financial or academic "credit" for clinician engagement in clinical research may boost participation rates in clinical studies., Conclusion: Maximizing clinician engagement is important for the success of clinical trials; the strategies employed in the ADAPTABLE trial may serve as a template for future pragmatic studies.

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.)., (Copyright © 2021 Massachusetts Medical Society.)

Background: New considerations during the ethical review processes may emerge from innovative, yet unfamiliar operational methods enabled in pragmatic randomized controlled trials (RCT), potentially making institutional review board (IRB) evaluation more complex. In this manuscript, key components of the pragmatic "Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-term Effectiveness (ADAPTABLE)" randomized trial that required a reappraisal of the IRB submission, review, and approval processes are discussed., Main Text: ADAPTABLE is a pragmatic, multicenter, open-label RCT evaluating the comparative effectiveness of two doses of aspirin widely used for secondary prevention (81 mg and 325 mg) in 15,000 patients with an established history of atherosclerotic cardiovascular disease. The electronic informed consent form is completed online by the participants at the time of enrollment, and endpoint ascertainment is conducted through queries of electronic health records. IRB challenges encountered regarding centralized IRB evaluation, electronic informed consent, patient engagement, and risk determination in ADAPTABLE are described in this manuscript. The experience of ADAPTABLE encapsulates how pragmatic protocol components intended to facilitate the study conduct have been tempered by unexpected, yet justified concerns raised by local IRBs. How the lessons learned can be applied to future similar pragmatic trials is delineated., Conclusion: Development of engaging communication channels between IRB and study personnel in pragmatic randomized trials as early as at the time of protocol design allows to reduce issues with IRB approval. Integrations of the lessons learned in ADAPTABLE regarding the IRB process for centralized IRBs, informed consent, patient engagement, and risk determination can be emulated and will be instrumental in future pragmatic studies.

Importance: Determining the right dosage of aspirin for the secondary prevention treatment of atherosclerotic cardiovascular disease (ASCVD) remains an unanswered and critical question., Objective: To report the rationale and design for a randomized clinical trial to determine the optimal dosage of aspirin to be used for secondary prevention of ASCVD, using an innovative research method., Design, Setting, and Participants: This pragmatic, open-label, patient-centered, randomized clinical trial is being conducted in 15 000 patients within the National Patient-Centered Clinical Research Network (PCORnet), a distributed research network of partners including clinical research networks, health plan research networks, and patient-powered research networks across the United States. Patients with established ASCVD treated in routine clinical practice within the network are eligible. Patient recruitment began in April 2016. Enrollment was completed in June 2019. Final follow-up is expected to be completed by June 2020., Interventions: Participants are randomized on a web platform in a 1:1 fashion to either 81 mg or 325 mg of aspirin daily., Main Outcomes and Measures: The primary efficacy end point is the composite of all-cause mortality, hospitalization for nonfatal myocardial infarction, or hospitalization for a nonfatal stroke. The primary safety end point is hospitalization for major bleeding associated with a blood-product transfusion. End points are captured through regular queries of the health systems' common data model within the structure of PCORnet's distributed data environment., Conclusions and Relevance: As a pragmatic study and the first interventional trial conducted within the PCORnet electronic data infrastructure, this trial is testing several unique and innovative operational approaches that have the potential to disrupt and transform the conduct of future patient-centered randomized clinical trials by evaluating treatments integrated in clinical practice while at the same time determining the optimal dosage of aspirin for secondary prevention of ASCVD., Trial Registration: ClinicalTrials.gov Identifier: NCT02697916.

Aspirin is the cornerstone of the antithrombotic management of patients with established atherosclerotic cardiovascular disease, but major guidelines provide conflicting recommendations for its use in primary prevention. Findings from recent randomized trials totaling >47 000 patients called into question the net clinical benefits of aspirin in primary prevention for 3 key populations: patients with diabetes mellitus, community-dwelling elderly individuals, and patients without diabetes mellitus who are at intermediate risk for atherosclerotic events. In the context of increasing emphasis on the use of other treatments for primary prevention in patients with moderate-high future risk of developing atherosclerotic cardiovascular disease, the efficacy and safety of aspirin for primary prevention has become uncertain. Key unresolved questions regarding the role of aspirin in primary prevention include the optimal drug formulation, dosing schedule, weight-based dose selection, and interplay between sex and treatment response. In the current era, most patients without established atherosclerotic cardiovascular disease should not be prescribed aspirin. Rather, aggressive management of comorbidities tailored to the expected cardiovascular risk needs to be emphasized. In this context, informed shared decision making between clinicians and patients regarding the use of aspirin for primary prevention of cardiovascular events is a suitable and laudable approach. In this article, we revisit the role of aspirin for the primary prevention of cardiovascular diseases by critically reviewing the key scientific literature, highlight key areas of uncertainties for future research, and propose a decisional framework for clinicians to support prescription of aspirin in primary prevention.