Aspirin for Primary Prevention of Atherosclerotic Cardiovascular Disease Advances in Diagnosis and Treatment

IMPORTANCE Clinical decision making regarding the appropriate use of aspirin for the primary prevention of atherosclerotic cardiovascular disease (ASCVD) events is complex, and requires an individualized benefit to risk assessment. OBJECTIVE To review advances in the individualized assessment for ASCVD and bleeding risk, and to provide an update of the randomized clinical trial evidence that examined the use of aspirin for primary prevention (primarily for ASCVD, and secondarily for colorectal cancer). The recently released 2016 US Preventive Services Task Force recommendations are discussed, as well as the role of ASCVD risk, age, sex, and aspirin dose/formulation in clinical decision making. EVIDENCE REVIEW We performed a detailed review of peer-reviewed publications that were identified through searches of MEDLINE and the Cochrane Database through 2016 using the literature search terms "aspirin," "primary prevention," "cardiovascular disease," "mortality," "cancer." Bibliographies from these references as well as meta-analyses of these randomized clinical trials were also reviewed. FINDINGS Evidence from a total of 11 trials involving more than 118000 patients is available to guide clinical decision making for aspirin use in the primary prevention of ASCVD. Clinicians should balance the benefit to risk ratio and the individual's preferences, calculating the 10-year ASCVD risk and evaluating risk factors for gastrointestinal bleeding, to facilitate a safer and more personalized approach to appropriate selection of candidates for low-dose aspirin (75 to 81 mg/d) for the primary prevention of ASCVD, with secondary considerations for reducing colorectal cancer risk when taken for longer periods (> 10 years). Both the net ASCVD benefit and the bleeding risk of aspirin therapy increased as the absolute ASCVD risk increased, but the net benefits generally exceeded the risks at higher baseline ASCVD risk (> 10% ASCVD 10-year risk). The Aspirin-Guide is a clinical decision making support tool (app for mobile devices) with internal risk calculators to help clinicians with this dual assessment by calculating the ASCVD risk and the bleeding risk in the individual patient, and incorporating age-and sex-specific guidance based on randomized trial results. CONCLUSIONS AND RELEVANCE Balancing the benefit of ASCVD reduction with the risk of bleeding from low-dose aspirin is difficult but essential for informed decision making and achieving a net clinical benefit from aspirin for primary prevention. This is facilitated by a free and readily available evidence-based clinical decision support tool.