Patients with both symptomatic and asymptomatic peripheral artery disease (PAD) may have an elevated risk for abdominal aortic aneurysm (AAA), according to research results published in Atherosclerosis.
While current United States Preventive Services Taskforce (USPSTF) guidelines recommend a one-time screening for AAA in men between 65 and 75 years with a history of smoking, recent research has shown that PAD may also be an independent risk factor for AAA, regardless of smoking status. The American Heart Association guidelines, therefore, recommend a screening duplex ultrasound for AAA in those with symptomatic PAD, but there are limited epidemiological data on the association of asymptomatic PAD and AAA.
In the current study, researchers conducted a prospective, cross-sectional investigation of the relationship between symptomatic and asymptomatic PAD with AAA using data from the Atherosclerosis Risk in Communities (ARIC) study to address this clinical question.
The current study included 2 analyses: the primary outcome—a prospective analysis with incident AAA—and a secondary analysis, cross-sectional in nature, with ultrasound-based AAA diagnosis.
For the primary analysis, researchers used data from all ARIC participants at visit 1 (1987-1989); those with a race/ethnicity other than White or Black, those with AAA surgery prior to visit 1, and those with missing baseline ankle brachial index (ABI) and other variables of interest were excluded, leading to a sample of 14,148 participants.
The secondary analysis used data from ARIC cohort visit 5 (2011-2013). After exclusion criteria were applied—participants with a race/ethnicity other than White or Black, those with missing aortic diameter variables, and those with missing ABI values—a total of 4664 participants remained.
For the primary analysis, mean age at baseline of the 14,148 participants was 54.1±5.7 years; 25.5% of participants were Black and 55.1% were women. A total of 11.6% had diabetes, 30.3% were taking antihypertensive medications and more than half (57.1%) were former smokers. Overall, 124 participants had symptomatic PAD. Median ABI at visit 1 among those without symptomatic PAD was 1.13 and a total of 3.9% of participants had an ABI ≤0.9.
During a median of 22.5 years of follow-up, 3.7% of participants developed incident AAA, with a crude incidence rate of 1.9 per 1000 person-years. Of these, 30.7% of cases either ruptured or required repair. Investigators found a strong association between symptomatic PAD and incident AAA in Kaplan Meier survival analyses, with a 15-year cumulative AAA incidence of 12.3% in symptomatic patients.
Those with asymptomatic PAD and ABI ≤0.9 also had a higher cumulative AAA incidence vs other ABI categories (15-year cumulative incidence, 3.9% vs 1.5%-2.4%, respectively).
Associations were statistically significant after adjusting for demographic variables for symptomatic and asymptomatic PAD vs ABI (hazard ratios [HRs], 4.91, 2.23). In a second model, slight attenuation was noted but both associations were statistically significant (HR, 2.96 and 1.52). The “borderline low” ABI category (>0.9-1.0) showed a significant association with incident AAA in model 1.
Mean age of participants in the secondary cross-sectional analysis who underwent an abdominal aortic duplex exam was 75.4±5.1 years. Just over 11% of participants had symptomatic PAD, and median ABI in those without symptomatic PAD was 1.13; 6.3% of participants had an ABI ≤0.9.
Overall mean proximal, mid, and distal anterior-posterior abdominal aortic diameters were 2.0±0.3 cm, 1.9±0.4 cm, and 1.8±0.4 cm, respectively.
Results of a multivariable logistic regression analysis showed that those with asymptomatic PAD and ABI ≤0.9 had a statistically increased prevalence of AAA vs those with ABI >1.1-1.2 (odds ratio [OR], 3.98). In Model 2, this was slightly attenuated but still significant (OR, 2.20). Adjustment for smoking pack-years did not “materially alter” the result.
Compared with no PAD, symptomatic PAD was significantly associated with AAA in Model 1 (OR, 2.46). An ABI 0.9 to 1.0 did not reach statistical significance, while ABI 1.0 to 1.1 demonstrated significantly higher AAA odds vs ABI >1.1 to 1.2 across 3 models.
An additional analysis to assess the association of PAD and AAA with incident cardiovascular events was also performed using data from the prospective cohort. Investigators found a statistically significant association of PAD without AAA with incident cardiovascular events (HR, 1.64). PAD with AAA had a HR of 2.28, which was deemed an imprecise estimate due to a lack of power.
Study limitations include the identification of AAA using only hospital diagnostic codes, slightly different ABI measurement protocols between visit 1 and visit 5, and the possibility of residual confounding.
“Based on population-based ARIC data, we found a statistically significant positive association of symptomatic PAD with incident AAA,” the researchers stated. “Our data support the current recommendation of AAA screening in symptomatic PAD patients and suggest the potential extension to those with asymptomatic PAD as well.”
Hicks CW, Al-Qunaibet A, Ding N, et al. Symptomatic and asymptomatic peripheral artery disease and the risk of abdominal aortic aneurysm: The Atherosclerosis Risk in Communities (ARIC) study. Atherosclerosis. Published online August 14, 2021. doi:10.1016/j.atherosclerosis.2021.08.016