Background

This study aims to assess how the prevalence and growth rates of small and medium AAAs (3.0-5.4cm) have changed over time in men aged 65 years, and to evaluate long-term outcomes in those men whose aortic diameter is 2.6-2.9cm (subaneurysmal), and below the standard threshold for most surveillance programmes.

Methods

The Gloucestershire Aneurysm Screening Programme (GASP) started in 1990. Men aged 65 years with an aortic diameter of 2.6-5.4cm, as measured by ultrasound using the inner to inner wall method, were included in surveillance. Aortic diameter growth rates were estimated separately for men who initially had a subaneurysmal aorta, or who had a small or medium AAA, using mixed-effects models.

Results

Since 1990, 81,150 men had ultrasound screening for AAA (uptake 80.7%), of whom 2,795 had an aortic diameter of 2.6-5.4cm. The prevalence of screen-detected AAA ≥3.0cm decreased from 5.0% in 1991 to 1.3% in 2015. There was no evidence of a change in AAA growth rates during this time. Of men who initially had a subaneurysmal aorta, 58% (95% CI 54, 61) were estimated to develop an AAA ≥3.0cm within 5 years of their initial scan, and 28% (95% CI 24, 32) were estimated to develop a large AAA (≥5.5cm) within 15 years.

Conclusions

The prevalence of screen-detected small and medium AAA has decreased over the last 25 years, but growth rates have remained similar. Men with a subaneurysmal aorta at age 65 have a substantial risk of developing a large AAA by the age of 80 years.