Abstract P307: The Impact of Aspirin Primary Prevention Treatment Guidelines, 2007-2015: Aspirin Use Stratified by Cardiovascular Disease Risk
Authors: Van’t Hof Jeremy R , Duval Sue , Walts Adrienne , Luepker Russell V , Hirsch Alan T 
Published: July 2021

Background:
Current national cardiovascular disease primary prevention (PP) guidelines recommend low dose aspirin (ASA) to prevent a first heart attack or stroke in appropriate candidates. The 2009 United States Preventive Services Task Force (USPSTF) ASA primary prevention recommendation was not widely implemented, and minimal data exist to define the efficacy of this “A” level recommendation. This study was designed to evaluate the impact of this recommendation on PP ASA use in primary care clinics in a large, regional health system over a 9 year period (2007-2015) stratifying patients by their 10 year global risk for a primary ischemic event.

Methods:
Bi-annual, cross-sectional electronic medical record (EMR) data were collected from 2007 to 2015 to evaluate documented ASA use for all office-based encounters involving a primary care provider within the Fairview Health System (Minnesota). PP candidates were defined as individuals within the USPSTF guideline target population (men ages 45-79 and women ages 55-79 years) with no documented history of an atherosclerotic syndrome. Appropriate ASA use candidates were defined as PP individuals with no ASA use contraindications (peptic ulcer disease, gastrointestinal bleeding or use of other antithrombotic medications). Ten year cardiovascular disease (CVD) risk was calculated using the ACC/AHA 2013 global risk calculator. ASA use was evaluated bi-annually in the total PP population and a stratified subset characterized by <10%, 10-20% and >20% ten year risk of an ischemic event. Secondary prevention (SP) ASA use was assessed as a reference standard for ideal penetration of guideline recommended ASA use.

Results:
Over 270,000 unique encounters were evaluated over the 9 year study period. Of those, 88,055 were PP ASA candidates with data for risk score calculation. Appropriate PP ASA use rates did not improve throughout the study period, with an average of 43% PP ASA use compared to 77% in the SP population. When stratified by <10%, 10-20% and >20% ten year CVD risk, average appropriate PP ASA use was 41%, 63% and 73% respectively, representing an absolute difference of 36%, 14% and 4% respectively compared to SP ASA use. Appropriate PP ASA use did not increase in any risk category following the publication of the 2009 USPSTF guidelines. Documented contraindications to ASA use were very low (6%) in the PP population.

Conclusion:
Appropriate PP ASA use in primary care settings increases as CVD risk increases. PP ASA use in the highest risk population is similar to the rate in the SP cohort. A large primary prevention aspirin treatment gap exists in the medium and low CVD risk categories. Publication of the 2009 USPSTF recommendation was not associated with improved aspirin use in any risk category. Public health interventions to safely and effectively disseminate this PP ASA recommendation, involving both the public and health care providers, are warranted.