Demographics of Abdominal Aortic Aneurysm
Abdominal aortic aneurysm predominantly affects older men, with the highest prevalence in males aged 65-75 years who have ever smoked, where rates reach 9-22% in Western populations. 1, 2
Age Distribution
- AAA prevalence increases progressively with age, rising from 5.4% at age 65 to 10.4% by age 80 in men. 3
- Most AAA-related deaths occur in men younger than age 80 years, with almost all deaths occurring in men older than age 65. 1
- In women, most AAA-related deaths occur in those older than age 80 years, reflecting both lower prevalence and later presentation. 1
- The condition is most clinically relevant in the 65-75 year age group, where screening demonstrates the greatest mortality benefit. 1, 4
Sex Distribution
- Men have a 5- to 13-fold higher baseline risk of AAA compared with women of the same age group. 2
- Overall prevalence in screening studies is approximately 4-9% in men versus 1% in women. 1
- Women have roughly one-sixth the prevalence observed in men across all age groups and risk categories. 1, 2, 4
- In a large U.S. screening database, 2.82% of all participants had AAA, with males showing significantly higher rates (OR 3.24). 5
Smoking Status
- Smoking is the single most powerful modifiable risk factor, with current smokers showing dramatically elevated risk (OR 3.28 for current smokers, OR 1.86 for former smokers). 5
- "Ever smoking" is defined as having smoked at least 100 cigarettes in one's lifetime. 1, 4
- In men aged 65-75 who have ever smoked, prevalence ranges from 9.1% to 22%. 2
- Female ever-smokers aged 65-75 have a prevalence of approximately 1.7%, substantially lower than male smokers but higher than never-smoking women. 5
- Current smoking status carries the highest risk, with current smokers showing OR 6.33 in females and OR 2.50 in males compared to never-smokers. 5
Race and Ethnicity
- Black race is associated with decreased risk of AAA. 1
- Most screening trial data come from predominantly Caucasian populations (83.4% Caucasian, 13.1% African American in one large U.S. database). 5
- Asian populations demonstrate lower prevalence than Western populations, with Filipino men expected to have lower rates than the 9-22% seen in Western cohorts. 2
Additional Risk Factors
Major risk factors beyond age, male sex, and smoking include: 1
- Family history of AAA (OR 1.60), particularly first-degree relatives requiring surgery 5
- Coronary heart disease and cardiac disease (OR 1.30 overall; OR 2.06 in male never-smokers) 1, 5
- Hypertension (present in 58.1% of screened individuals) 5
- Hypercholesterolemia (present in 54.9% of screened individuals) 5
- Claudication and cerebrovascular disease 1
- Increased height 1
Protective Factors
- Diabetes mellitus is consistently associated with decreased risk of AAA across all populations. 1, 2
- Female sex confers substantial protection independent of other factors. 1
Clinical Context
- The overall prevalence of AAA >5.0 cm in men aged 50-79 years is approximately 0.5%. 1
- Incidental detection rates on abdominal CT scans range from 2.2% to 5.8% in mixed-population cohorts. 2
- Rupture carries 75-90% mortality, with more than half of deaths occurring before hospital arrival, underscoring the importance of understanding at-risk demographics. 2
Common pitfall: Do not assume all elderly patients warrant screening—women who have never smoked have extremely low prevalence and should not undergo routine screening, as potential harms outweigh benefits. 1, 4