Estimation of Atherosclerotic Cardiovascular Disease Risk Among Patients in the Veterans Affairs Health Care System

Importance Current guidelines recommend statin therapy for millions of US residents for the primary prevention of atherosclerotic cardiovascular disease (ASCVD). It is unclear whether traditional prediction models that do not account for current widespread statin use are sufficient for risk assessment. Objectives To examine the performance of the Pooled Cohort Equations (PCE) for 5-year ASCVD risk estimation in a contemporary cohort and to test the hypothesis that inclusion of statin therapy improves model performance. Design, Setting, and Participants This cohort study included adult patients in the Veterans Affairs health care system without baseline ASCVD. Using national electronic health record data, 3 Cox proportional hazards models were developed to estimate 5-year ASCVD risk, as follows: the variables and published beta coefficients from the PCE (model 1), the PCE variables with cohort-derived beta coefficients (model 2), and model 2 plus baseline statin use (model 3). Data were collected from January 2002 to December 2012 and analyzed from June 2016 to March 2020. Exposures Traditional ASCVD risk factors from the PCE plus baseline statin use. Main Outcomes and Measures Incident ASCVD and ASCVD mortality. Results Of 1 & x202f;672 & x202f;336 patients in the cohort (mean [SD] baseline age 58.0 [13.8] years, 1 & x202f;575 & x202f;163 [94.2%] men, 1 & x202f;383 & x202f;993 [82.8%] white), 312 & x202f;155 (18.7%) were receiving statin therapy at baseline. During 5 years of follow-up, 66 & x202f;605 (4.0%) experienced an ASCVD event, and 31 & x202f;878 (1.9%) experienced ASCVD death. Compared with the original PCE, the cohort-derived model did not improve model discrimination in any of the 4 age-sex strata but did improve model calibration. The PCE overestimated ASCVD risk compared with the cohort-derived model; 211 & x202f;237 of 1 & x202f;136 & x202f;161 white men (18.6%), 29 & x202f;634 of 218 & x202f;463 black men (13.6%), 1741 of 44 & x202f;399 white women (3.9%), and 836 of 16 & x202f;034 black women (5.2%) would be potentially eligible for statin therapy under the PCE but not the cohort-derived model. When added to the cohort-derived model, baseline statin therapy was associated with a 7% (95% CI, 5%-9%) lower relative risk of ASCVD and a 25% (95% CI, 23%-28%) lower relative risk for ASCVD death. Conclusions and Relevance In this study, lower than expected rates of incident ASCVD events in a contemporary national cohort were observed. The PCE overestimated ASCVD risk, and more than 15% of patients would be potentially eligible for statin therapy based on the PCE but not on a cohort-derived model. In the statin era, health care professionals and systems should base ASCVD risk assessment on models calibrated to their patient populations. Question Are current risk prediction models accurate at estimating risk of initial atherosclerotic cardiovascular (ASCVD) events in veterans? Findings In this cohort study of 1 & x202f;672 & x202f;336 veterans with an outpatient visit between 2002 and 2007, the 2013 American College of Cardiology/American Heart Association model overestimated absolute risk of ASCVD during 5 years of follow-up. Statin use was associated with 7% lower relative risk of ASCVD and 25% lower relative risk of ASCVD mortality. Meaning The findings of this study suggest that reestimation and the inclusion of statin use in ASCVD prediction models might be needed for their appropriate use in a health care system. This cohort study examines the performance of the Pooled Cohort Equations (PCE) for 5-year atherosclerotic cardiovascular disease risk estimation in a contemporary cohort and tests the hypothesis that inclusion of statin therapy improves model performance.