Data Demonstrate Increased Risk of AAA in Both Symptomatic and Asymptomatic PAD

November 18, 2021—In a study published in Atherosclerosis, Hicks et al found an elevated risk of abdominal aortic aneurysm (AAA) in patients with both symptomatic and asymptomatic peripheral artery disease (PAD) using prospective and cross-sectional data from the ARIC study.

Investigators conducted two analyses based on data from the prospective ARIC study of adults aged 45 to 64 years who initially presented between 1987-1989 from four United States communities (Washington County, Maryland; suburban Minneapolis, Minnesota; Jackson, Mississippi; and Forsyth County, North Carolina). The primary analysis was a prospective analysis of incident AAA based on clinical diagnosis obtained through annual follow-up phone calls, medical records, surveillance of hospital records, and data linked from the Centers for Medicare & Medicaid Services over a median follow-up of 22.5 years. The secondary analysis was a cross-sectional analysis of AAA diameter (≥ 3.0 cm) as measured by high-resolution, real-time duplex ultrasound.

Of 15,792 patients in the primary analysis of all ARIC participants at visit 1 (1987-1989), 14,148 were included. Data from visit 5 of the ARIC study cohort (2011-2013) were used for the secondary analysis, which included 4,664 of 6,538 patients.

For the prospective analysis, symptomatic PAD was defined based on the presence of intermittent claudication or a history of prior lower extremity revascularization at visit 1. For the cross-sectional analysis, symptomatic PAD was defined based on self-reported leg pain symptoms, prior lower extremity revascularization, and/or a hospital diagnosis of critical limb ischemia at or prior to visit 5. Asymptomatic PAD was based on ankle-brachial index (ABI).

The prospective analysis compared baseline characteristics across categories of symptomatic PAD, asymptomatic PAD (ABI ≤ 0.9), and five other ABI categories (> 0.9-1.0, > 1.0-1.1, > 1.1-1.2, > 1.2-1.3, and > 1.3) and examined their association with incident AAA. Three Cox proportional hazard models were created. ABI category > 1.1 to 1.2 was considered the reference group because it was the largest in the study population. The cross-sectional analysis used the same categories as the prospective analysis and quantified them with the presence of AAA on duplex ultrasound. Multivariable regression was used, adjusting for potential confounders from visit 5.

For the primary prospective analysis, mean age of patients at baseline was 54.1 (SD 5.7) years, 25.5% were Black, 55.1% were female, 11.6% had diabetes, 30.3% were on antihypertensive medications, and 57.1% were current or former smokers. Over a median of 22.5 years of follow-up, 3.7% of participants developed incident AAA (crude incidence rate, 1.9/1,000 person-years). The 15-year cumulative incidence of AAA was 12.3% for symptomatic PAD, 3.9% for asymptomatic PAD, and 1.5% for the reference ABI group. The associations were still statistically significant after adjusting for demographic variables (symptomatic PAD: hazard ratio [HR], 4.91; 95% CI, 2.88-8.37; asymptomatic PAD: HR, 2.33; 95% CI, 1.55-3.51).

For the secondary cross-sectional analysis, mean age of patients who underwent duplex ultrasound was 75.4 (SD 5.1) years, and 11.1% had symptomatic PAD. The overall mean maximum AAA diameter was 2.1 (SD 0.4) cm, and 2.3% of participants had AAA based on ultrasound measurements. Multivariable logistic regression analysis showed a similar pattern of association with ultrasound-based AAA as was seen in the prospective analysis (symptomatic PAD: odds ratio [OR], 2.46; 95% CI, 1.26-4.81; asymptomatic PAD: OR, 3.98; 95% CI, 1.96-8.08).

These findings support the current recommendation of AAA screening in patients with symptomatic PAD and suggest that screening should be extended to those with asymptomatic PAD as well, noted the investigators.