Introduction: Atherosclerotic cardiovascular disease (ASCVD) is a general term for a group of diseases characterized by atherosclerosis that affect the heart and blood vessels. ASCVD is the leading cause of death in the United States contributing to at least 200,000 preventable deaths from heart disease and stroke each year. Cardiovascular disease, heart disease, and stroke mortality has declined since the year 2000, due to broader use of evidence-based therapies and changes to risk factors and lifestyle modifications, but the decline began to slow after 2011. Two main risk factors contributing to ASCVD are high blood pressure and high cholesterol. Efforts have been made to increase control of these factors at the population-level, however, only those who are diagnosed can be treated. While awareness has increased over time, there is still a significant contribution to ASCVD events from those who were undiagnosed but have high blood pressure, high cholesterol, and/or diabetes.
Hypothesis: To assess how much of the total U.S. population ASCVD risk is undiagnosed from 1999-2014.
Methods: The Pooled Cohort Equations assessed 10-year ASCVD risk, based on age, sex, race, total cholesterol, HDL level, systolic blood pressure, use of blood pressure medication, smoking status, and diabetes status. The undiagnosed risk of the primary risk population (age 40-79 years, without missing values for necessary cholesterol, blood pressure, and glucose measures) from 1999-2014 Continuous National Health and Nutrition Examination Survey (NHANES) was calculated based on self-report questions and clinical measures, after age, sex, race, smoking, and diagnosed risks were accounted for. Linear regression for complex survey data tested whether undiagnosed risk was changing over time.
Results: Applying the ASCVD risk equation to the NHANES subset (n=8,763; weighted n=104,421,757), undiagnosed conditions were associated with 10% of the projected ASCVD events. That is, per 100,000 Americans in this subset, 7,747 ASCVD events were estimated over 10-years, and 800 were based on risk from undiagnosed diabetes, hypercholesterolemia, or hypertension. However, ASCVD risk associated with undiagnosed conditions over time decreased (p<0.001), from 1,169 per 100,000 in 1999-2000, to 642 per 100,000 in 2013-2014.
Conclusions: NHANES creates a unique opportunity to quantify undiagnosed ASCVD risk in a nationally representative sample. Since 1999, a sizeable portion of the US primary ASCVD risk was based on undiagnosed conditions, however, this proportion of undiagnosed risk decreased over time.