Comorbidities Associated with Large Abdominal Aortic Aneurysms

Association between socioeconomic deprivation and presentation with a ruptured abdominal aortic aneurysm

OBJECTIVE

Given the ongoing nature of research in the social determinants space and urges to improve United States Preventive Services Task Force screening efforts for abdominal aortic aneurysms (AAAs), this project aims to characterize the association between the level of socioeconomic deprivation, rurality, and ruptured AAA (rAAA) presentation across the United States.

METHODS

We queried the Vascular Quality Initiative registry (2010-2019) for patients with AAAs. The area deprivation index (ADI) is an index from 1 to 100 used to capture socioeconomic status. ADI was grouped into quintiles, with the most deprived regions being quintile 5 and having the highest ADI index. Multivariable logistic regression assessed the association between ADI, rurality, and rAAA presentation overall and before age 65.

RESULTS

Of the 82,909 patients included, 11,458 patients (14%) resided in the most socioeconomically deprived regions, and 18,083 patients (22%) lived in rural regions. Overall, 6831 patients (8.2%) experienced an rAAA, with 4696 patients (69%) residing in the three most deprived quintiles. Most patients underwent endovascular repair (n = 67,933; 82%), followed by open repair (n = 14,976; 18%). On multivariable analysis, residence in the most socioeconomically deprived region was associated with a near 1.5-fold increased odds of presenting with an rAAA compared with a residence in the least deprived regions (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.31-1.63; P < .001), whereas urban residence was associated with a decreased odds to present with an rAAA compared with rural residence (OR, 0.84; 95% CI, 0.79-0.89; P < .001). When stratifying the study population by the United States Preventive Services Task Force recommended age for AAA screening (65 years old), 14,147 patients (17%) were under 65. Of those under 65, 1381 patients (9.8%) experienced a rAAA, and 9955 patients (71%) resided in the three most deprived quintiles. Residence in the most socioeconomically deprived region was associated with an increased odds of presenting with an rAAA compared with residence in the least deprived region (OR, 1.31; 95% CI, 1.01-1.69; P = .042). However, there were no significant associations between rural residence and increased rAAA presentation among individuals under 65 (OR, 1.07; 95% CI, 0.93-1.23; P = .36).

CONCLUSIONS

Among all patients in this study, patients residing in highly socioeconomically deprived or rural regions were more likely to present with an rAAA, but among those under 65, only residence in a socioeconomically deprived area was associated with increased odds of rAAA presentation. Understanding the effects of socioeconomic deprivation on rAAA presentation can identify at-risk populations for early AAA screening before rupture.

A machine learning approach for predicting complications in descending and thoracoabdominal aortic aneurysms

OBJECTIVE

To use machine learning to predict rupture, dissection, and all-cause mortality for patients with descending and thoracoabdominal aortic aneurysms in an effort to improve on diameter-based surgical intervention criteria.

METHODS

Retrospective data from 1083 patients with descending aortic diameters 3.0 cm or greater were collected, with a mean follow-up time of 3.52 years and an average descending diameter of 4.13 cm. Six machine learning classifiers were trained using 44 variables to predict the occurrence of dissection, rupture, or all-cause mortality within 1, 2, or 5 years of initial patient encounter for a total of 54 (6 × 3 × 3) separate classifiers. Classifier performance was measured using area under the receiver operator curve.

RESULTS

Machine learning models achieved area under the receiver operator curves of 0.842 to 0.872 when predicting type B dissection, 0.847 to 0.856 when predicting type B dissection or rupture, and 0.820 to 0.845 when predicting type B dissection, rupture, or all-cause mortality. All models consistently outperformed descending aortic diameter across all end points (area under the receiver operator curve = 0.713-0.733). Feature importance inspection showed that other features beyond aortic diameter, such as a history of myocardial infarction, hypertension, and patient sex, play an important role in improving risk prediction.

CONCLUSIONS

This study provides surgeons with a more accurate, machine learning-based, risk-stratification metric to predict complications for patients with descending aortic aneurysms.

Prospect of positron emission tomography for abdominal aortic aneurysm risk stratification

Abdominal aortic aneurysm (AAA) disease is characterized by an asymptomatic, permanent, focal dilatation of the abdominal aorta progressing towards rupture, which confers significant mortality. Patient management and surgical decisions rely on aortic diameter measurements via abdominal ultrasound surveillance. However, AAA rupture can occur at small diameters or may never occur at large diameters, implying that anatomical size is not necessarily a sufficient indicator. Molecular imaging may help identify high-risk patients through AAA evaluation independent of aneurysm size, and there is the question of the potential role of positron emission tomography (PET) and emerging role of novel radiotracers for AAA. Therefore, this review summarizes PET studies conducted in the last 10 years and discusses the usefulness of PET radiotracers for AAA risk stratification. The most frequently reported radiotracer was [18F]fluorodeoxyglucose, indicating inflammatory activity and reflecting the biomechanical properties of AAA. Emerging radiotracers include [18F]-labeled sodium fluoride, a calcification marker, [64Cu]DOTA-ECL1i, an indicator of chemokine receptor type 2 expression, and [18F]fluorothymidine, a marker of cell proliferation. For novel radiotracers, preliminary trials in patients are warranted before their widespread clinical implementation. AAA rupture risk is challenging to evaluate; therefore, clinicians may benefit from PET-based risk assessment to guide patient management and surgical decisions.

Do Hernias Contribute to Increased Severity of Aneurysmal Disease among Abdominal Aortic Aneurysm Patients?

Background  Connective tissue disorders could contribute to the pathogenesis of both abdominal aortic aneurysms (AAA) and hernias. We tested the hypothesis that hernias in AAA patients contribute to increased severity of the aneurysmal disease.

Methods  A questionnaire was used to collect information from 195 AAA patients divided into four groups: (1) survivors ( n  = 22) of ruptured AAA, (2) patients ( n  = 90) after elective open repair, (3) patients ( n  = 43) after elective endovascular repair (EVAR), and (4) patients ( n  = 40) under surveillance of AAA. The control group consisted of 100 patients without AAA whose abdominal computed tomography (CT) scans were examined for the presence of hernias. Mann–Whitney U -test, Chi-squared ( χ² ) test, or Fisher's exact test (as appropriate) were used for statistical analyses. Multivariate logistic regression was used to control for potential confounding variables such as sex and age.

Results  The prevalence of inguinal hernias was significantly higher in the AAA than the control group (25 vs. 9%, p  = 0.001) and did not differ between the AAA subgroups (9, 24, 35, and 23% in subgroups 1 through 4, respectively, p  = 0.15) based on univariate analysis. The prevalence of inguinal hernias did not differ ( p  = 0.15) between the two open surgery groups (groups 1 and 2), or when comparing all three operative procedures as a combined group to group 4 ( p  = 0.73). The prevalences of incisional hernias were 18 and 24% for groups 1 and 2, respectively, with no significant difference ( p  = 0.39). Inguinal hernia demonstrated a significant association with AAA on multivariate analysis ( p  = 0.006; odds ratio [OR] = 4.00; 95% confidence interval [CI] = 1.49–10.66).

Conclusions  Our study confirms previous observations that patients with AAA have a high prevalence of hernias. Our results suggest that hernias do not contribute to increased severity of the aneurysmal disease.

Abdominal aortic aneurysms and abdominal wall hernias - a systematic review and meta-analysis

Background: Abdominal wall hernias (AWHs) share common epidemiological characteristics with abdominal aortic aneurysms (AAAs), typically presenting in male population and older ages. Prior reports have associated those two disease entities. Our objective was to perform a systematic review and meta-analysis and examine whether AAA rates are higher among patients with AWH vs controls and whether the incidence of AWH was higher among patients with AAA vs patients without AAA. Methods: We performed a systematic review and meta-analysis according to the PRISMA guidelines. The Medline database was searched up to July 31, 2020. A random effects meta-analysis was performed. Results: In total, 17 articles and 738,972 participants were included in the systematic review, while 107,578 patients were eligible for the meta-analysis. Among four studies investigating the incidence of AAA in patients with hernias, AAA was more common in patients with hernias, compared to patients without hernias. [OR: 2.53, 95% CI: 1.24-5.16, I²=81.6%]. Among thirteen studies that compared patients with known AAA vs no AAA, the incidence of hernias was higher in patients with AAA, compared with patients without AAA [OR: 2.27, 95% CI: 1.66-3.09, I²=84.6%]. Conclusions: Our study findings indicate that a strong association between AWH and AAA exists. AWHs could therefore be used as an additional selection criterion for screening patients for AAA, apart from age, gender, family history and smoking.

Association of simple renal cysts and chronic kidney disease with large abdominal aortic aneurysm

Background

Abdominal aortic aneurysms (AAA) primarily affect men over 65 years old who often have many other diseases, with similar risk factors and pathobiological mechanisms to AAA. The aim of this study was to assess the prevalence of simple renal cysts (SRC), chronic kidney disease (CKD), and other kidney diseases (e.g. nephrolithiasis) among patients presenting with AAA.

Methods

Two groups of patients (97 AAA and 100 controls), with and without AAA, from the Surgical Clinic Charité, Berlin, Germany, were selected for the study. The control group consisted of patients who were evaluated for a kidney donation (n = 14) and patients who were evaluated for an early detection of a melanoma recurrence (n = 86). The AAA and control groups were matched for age and sex. Medical records were analyzed and computed tomography scans were reviewed for the presence of SRC and nephrolithiasis.

Results

SRC (74% vs. 57%; p<0.016) and CKD (30% vs. 8%; p<0.001) were both more common among AAA than control group patients. On multivariate analysis, CKD, but not SRC, showed a strong association with AAA.

Conclusions

Knowledge about pathobiological mechanisms and association between CKD and AAA could provide better diagnostic and therapeutic approaches for these patients.