A, Average primary annual incidence rates of coronary heart disease, heart failure, stroke, or intermittent claudication. B, Numbers of US residents without clinical atherosclerotic cardiovascular disease represented in the 2005-2010 National Health and Nutrition Examination Survey. C, Percentage of the expected total of 930 621 annual primary events in men and 702 105 in women by age group.
Sniderman AD, Thanassoulis G, Williams K, Pencina M. Risk of Premature Cardiovascular Disease vs the Number of Premature Cardiovascular Events. JAMA Cardiol. 2016;1(4):492-494. doi:10.1001/jamacardio.2016.0991
The risk of new-onset cardiovascular disease (CVD) is low before the age of 40 years, increases steadily between 40 and 60 years, but jumps sharply thereafter.1 Consequently, treatment guidelines, which are based on risk, recommend preventive therapy most commonly for individuals older than 60 years.2 However, the distribution of the population is not uniform across the age spectrum and therefore risk does not necessarily reflect the absolute number of cardiovascular events at different ages. Accordingly, we have estimated the expected number of new-onset cardiovascular events per decade across the age spectrum beginning at age 45 years.
This study was conducted from November 1, 2015, to January 19, 2016. To estimate the sex-specific incidence of total new-onset cardiovascular events per age decade, we used the average event rates included in the American Heart Association 2015 heart disease and stroke statistical update.1 We also estimated the number of US residents free of clinical atherosclerotic CVD as defined by the 2013 American College of Cardiology/American Heart Association cholesterol guidelines,2 applying the 2005-2010 National Health And Nutrition Examination Survey as previously described.3 We then applied the average annual incidence rates to the populations at risk by age decade and sex. As the study used published results and publicly available survey data from the National Health And Nutrition Examination Survey, no institutional review board approval was necessary. The National Health And Nutrition Examination Survey does not contain any identifiable patient data, so no deidentification was needed.
In both women and men, the absolute rate of new-onset cardiovascular events increases sharply after 65 years (Figure, A). By contrast, the population at risk steadily decreases as age increases (Figure, B). As a result, in men, the number of new-onset cardiovascular events per age decade is roughly constant until age 85 years. About one-fourth of all new-onset cardiovascular events in men occur before age 55 years and half occur before age 65 years (Figure, C). In women, there is a progressive increase in the number of new-onset cardiovascular events such that about one-seventh of events occur before age 55 years and one-third occur before age 65 years. Despite the highest incidence rate among patients older than 84 years, events happening after this age contribute only a small fraction to the total count.
This analysis demonstrates that CVD is not only a disease that affects older individuals. On the contrary, virtually half the total events in men and almost one-third in women occur before age 65 years. For those with premature cardiovascular events, their personal, family, and societal contributions are cut short or diminished earlier, their earnings losses are greater, and for those who survive, their period of care is longer.4
In contrast to the hypertension guidelines, which initiate therapy based on blood pressure level alone, preventive therapy in current lipid guidelines is triggered primarily by risk exceeding a defined threshold.2 Because risk is strongly associated with age, the indication for preventive therapy increases substantially after age 60 years, from about 30% to almost 80%.3 Our results demonstrate that, by this age, many cardiovascular events have already occurred. Furthermore, by age 60 years, asymptomatic intramural atherosclerotic disease is well advanced in many other individuals.
Our findings highlight the need to refine strategies to identify individuals younger than 60 years who are candidates for preventive therapies. Several options exist. The risk threshold used by the lipid guidelines could be lowered to the optional 5% level2 or age- and sex-specific thresholds could be adopted.5 Furthermore, as suggested, additional risk factors might be considered, such as a low-density lipoprotein cholesterol level of 160 mg/dL or more (to convert to millimoles per liter, multiply by 0.0259), family history of premature CVD, elevated C-reactive protein level, high calcium score, low ankle brachial index, or high lifetime risk of CVD.2 Finally, the benefit model of prevention has been recently proposed.6 This model takes into account the greater benefit of statins when patients have higher levels of low-density lipoprotein cholesterol and extends the risk strategy by including greater numbers of younger individuals with higher levels of low-density lipoprotein cholesterol without inflating the maximum number needed to treat.
Given the limited knowledge of long-term medication use and the lower absolute risk of CVD at younger ages, indiscriminate use of medications is not reasonable. Any preventive strategy must include health promotion across the life span, enhancing societal efforts to eradicate CVD, and new strategies to prevent premature cardiovascular events.
Accepted for Publication: March 23, 2016.
Corresponding Author: Allan D. Sniderman, MD, Royal Victoria Hospital-McGill University Health Centre, 1001 Decarie Blvd, Montreal, Quebec H4A 3J1, Canada (firstname.lastname@example.org).
Published Online: May 18, 2016. doi:10.1001/jamacardio.2016.0991.
Author Contributions: Mr Williams had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Sniderman, Williams, Pencina.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Sniderman, Williams.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Williams.
Study supervision: Sniderman.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.