Patients with symptomatic and asymptomatic peripheral arterial occlusive disease (PAOD) may be at increased risk for an abdominal aortic aneurysm (AAA), according to research published in Atherosclerosis.
While the current guidelines of the United States Preventive Services Taskforce (USPSTF) recommend a one-time screening for AAA in men between 65 and 75 years of age with a history of smoking, recent research has shown that PAD can also be an independent risk factor for AAA, regardless of smoking status. The American Heart Association guidelines therefore recommend duplex ultrasound screening for AAA in patients with symptomatic PAD, but there is limited epidemiological data on the association between asymptomatic PAD and AAA.
In the current study, researchers conducted a prospective cross-sectional study of the association between symptomatic and asymptomatic PAD with AAA using data from the Atherosclerosis Risk in Communities (ARIC) study to answer this clinical question.
The current study comprised 2 analyzes: the primary endpoint – a prospective analysis with incident AAA – and a secondary cross-sectional analysis with ultrasound-based AAA diagnosis.
For the primary analysis, researchers used data from all ARIC participants on Visit 1 (1987-1989); People of any race / ethnicity other than white or black, people with AAA surgery before visit 1, and people with no baseline ankle-arm index (ABI) and other variables of interest were excluded, resulting in a sample of 14,148 participants.
For the secondary analysis, data from ARIC cohort visit 5 (2011-2013) were used. After the exclusion criteria were applied – participants with a different race / ethnicity 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, the mean age of the 14,148 participants at baseline was 54.1 ± 5.7 years; 25.5% of the participants were black and 55.1% were women. 11.6% had diabetes, 30.3% were taking antihypertensive drugs, and more than half (57.1%) were former smokers. A total of 124 participants had symptomatic PAD. The median ABI at visit 1 in those without symptomatic PAD was 1.13 and a total of 3.9% of participants had an ABI ≤ 0.9.
During a median follow-up of 22.5 years, 3.7% of participants developed an AAA incidence, with a crude incidence rate of 1.9 per 1000 person-years. Of these, 30.7% of the cases either broke or had to be repaired. The researchers found a strong association between symptomatic PAD and AAA incidence in Kaplan-Meier survival analyzes, with a cumulative AAA incidence of 12.3% over 15 years in symptomatic patients.
Patients with asymptomatic PAD and an ABI 0.9 also had a higher cumulative AAA incidence compared to other ABI categories (15-year cumulative incidence, 3.9% vs. 1.5% -2.4%).
The associations were statistically significant after adjusting the demographic variables for symptomatic and asymptomatic PAD vs. ABI (hazard ratios [HRs], 4.91, 2.23). A second model found a slight attenuation, but both associations were statistically significant (HR 2.96 and 1.52). The ABI category “borderline low” (> 0.9-1.0) showed in model 1 a significant association with an AAA incident.
The mean age of the participants in the secondary cross-sectional analysis who underwent an abdominal aortic duplex exam was 75.4 ± 5.1 years. Slightly more than 11% of the participants had symptomatic PAD and the median ABI in those without symptomatic PAD was 1.13; 6.3% of the participants had an ABI ≤0.9.
Overall, the mean proximal, mean, 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.
The results of a multivariable logistic regression analysis showed that those with asymptomatic PAD and an ABI ≤ 0.9 had a statistically higher prevalence of AAA compared to those with ABI> 1.1–1.2 (odds ratio [OR], 3.98). In model 2 this was slightly weakened, but still significant (OR 2.20). The adjustment for smoker pack years did not “significantly” change the result.
Compared to no PAD, symptomatic PAD was significantly associated with AAA in model 1 (OR, 2.46). An ABI of 0.9 to 1.0 achieved no statistical significance, while an ABI of 1.0 to 1.1 showed significantly higher AAA rates compared to ABI> 1.1 to 1.2 in 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. The researchers found a statistically significant association of PAD without AAA with cardiovascular events (HR, 1.64). PAD with AAA had a HR of 2.28, which was estimated to be inaccurate due to lack of performance.
The limitations of the study 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 mix-ups.
“Based on population-based ARIC data, we found a statistically significant positive association between symptomatic PAD and AAA incidents,” the researchers said. “Our data support the current recommendation for AAA screening in symptomatic PAD patients and suggest a possible expansion to include patients with asymptomatic PAD.”
Hicks CW, Al-Qunaibet A, Ding N, et al. Symptomatic and Asymptomatic Peripheral Arterial Disease and the Risk of Abdominal Aortic Aneurysm: The Atherosclerosis Risk in Communities (ARIC) Study. Arteriosclerosis. Published online August 14, 2021. doi: 10.1016 / j.atherosclerosis.2021.08.016
This article originally appeared on The Cardiology Advisor