Abstract 385: The Impact of Aspirin Primary Prevention Treatment Guidelines: Temporal Trends in Aspirin Use for Primary vs Secondary Prevention, 2005-2013

Background: Current national prevention guidelines recommend use of low dose aspirin (ASA) for both the primary prevention (PP) and secondary prevention (SP) of heart attack and stroke. ASA use for SP has been documented to have increased over the past decade. Since the publication of the 2009 United States Preventative Services Task Force (USPSTF) recommendations for PP ASA use, data describing the trends in PP ASA use in primary care are sparse. This study evaluates trends in PP and SP ASA use in primary care clinics from a large, regional health system over an 8 year period (2005-2013). Methods: A bi-annual cross-sectional electronic medical record (EMR) chart extraction was performed from 2005 to 2013 to evaluate documented ASA use for all patient encounters within primary care clinics in the Fairview Health System (Minnesota). Primary prevention candidates were defined as individuals within the USPSTF guideline age and sex target populations (men aged 45-79, and women aged 55-79 years) with no documented history of an atherosclerotic syndrome or contraindication to ASA use (aspirin allergy, peptic ulcer disease, or concurrent antithrombotic therapy). Secondary prevention candidates were defined as adults within the same age and gender range with a history of coronary artery disease, peripheral artery disease or ischemic stroke. The ASA treatment to candidacy ratio was calculated for the PP and SP populations. Results: Over 225,000 unique encounters at 66 primary care clinics were analyzed over the 8 year study period. The PP population was younger (60.4±8.7 vs. 66.2±8.3 years), with lower prevalence of hypertension (49 vs. 79%), hyperlipidemia (54 vs. 84%), and diabetes (17 vs. 35%) compared to the SP cohort. The mean SP ASA use of 86% was high, concordant with national trends, and did not change over this period. In contrast, PP ASA average use was 44% with no increase after publication of the 2009 USPSTF guideline. Documented contraindications to ASA use were uncommon (ASA allergy, 2.1 and 2.8%; peptic ulcer disease, 3.2 and 7.2%; and use of other antithrombotic medications, 4.6 and 32.6% in PP and SP populations respectively). Conclusion: Secondary prevention ASA use in primary care settings remains high, but ASA use for primary prevention of cardiovascular events is low. Despite creation of national guidelines, aspirin use in the PP population is half the rate of ASA use for secondary prevention. Additional methods to safely and effectively disseminate this primary prevention aspirin use recommendation, targeting both the public and health care providers, are warranted.