Underutilization of Aspirin Persists in US Ambulatory Care for the Secondary and Primary Prevention of Cardiovascular Disease

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The gaps observed with secondary prevention are particularly concerning, given the existence of conclusive clinical evidence and unequivocal practice guidelines. The use of aspirin among primary prevention patients, including those with diabetes, also appears to be suboptimal, but additionally may reflect uncertainty about the evidence. Our analysis also suggests that, despite aspirinÔÇÖs more favorable cost-effectiveness, statins have been prioritized ahead of aspirin as therapy for reducing CVD risk.

While ample evidence attests to the underuse of aspirin in reducing risks of CVD, this study uniquely provides an 11-year trajectory of aspirin use in US outpatient settings and reveals that improvements have been at best modest. The magnitude of improvements seems particularly small in the context of often-repeated national guidelines and abundant clinical evidence supporting aspirin use for the prevention of CVD, particularly in patients with known CVD. Even in 2003, aspirin use was reported in only one-third of the visits by patients having CVD, which points to widespread underappreciation of aspirin as an efficacious and cost-effective secondary prevention therapy. The usage was 12% among visits by diabetics, a group at increased cardiovascular risk. This was lower than the 16% found among visits by patients with multiple major cardiovascular risk factors for whom evidence supporting prophylactic aspirin therapy is less definitive. The continued increases in aspirin use since 1999-2000 may reflect heightened awareness of the benefits of aspirin in reducing cardiovascular morbidity and mortality, mediated through intensified dissemination of national guidelines and clinical trial findings.2,9-11,32We did not find evidence of aspirin overuse in low-risk patients.

Compared with clinical practice in Europe,22,23 our study results add support to the observation that underuse of aspirin is more problematic in the US.The genesis of this gap is likely multifactorial and open to postulation. For instance, US physicians may face greater pressure than their European colleagues to prescribe newer medications as a result of less restrictive regulations on drug advertising. Also, direct-to-consumer advertising has been shown to change patient-physician relationships and physician prescribing behavior. The widespread aspirin underutilization could also be partly due to uncertainties in risk assessment. Healthcare providers show little consistency as to how much risk of excess bleeding is acceptable, which may partly account for the variability in aspirin prescribing.33 Data indicate that aspirin use is linked to approximately 2.5-4.5% of the annual upper gastrointestinal events (symptomatic ulcers) and 1-1.5% of serious complications, such as severe bleeding, perforation, and obstruction.34

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