Double-edged sword of diabetes mellitus for abdominal aortic aneurysm

Risk Factors for Abdominal Aortic Aneurysm in Patients With Diabetes

OBJECTIVE

Although diabetes has been shown to be negatively associated with development of abdominal aortic aneurysm (AAA), patients with diabetes may still develop aneurysms. In this study we examined risk factors for development of AAA in patients with diabetes.

METHODS

Adults over 50 years with diabetes who underwent health screening between 2009 and 2012 were followed for incident AAA until December 31, 2019. Cox proportional hazard regression models were used to calculate multivariate hazard ratios (HR) and 95% confidence intervals (CI) for risk factors associated with AAA.

RESULTS

Among 1,913,066 participants (55.3% men), 6,996 AAA cases were identified during a mean follow-up of 7.7 years. Increased AAA risk was observed for age ≥ 65 years (HR 2.69, 95% CI 2.55-2.83), men (HR 1.81, 95% CI 1.69-1.94), smoking (ex-smoker ≥ 20 pack-years, HR 1.75, 95% CI 1.61-1.89; current smoker < 20 pack-years, HR 1.76, 95% CI 1.59-1.94; current smoker ≥ 20 pack-years, HR 2.40, 95% CI 2.23-2.59), abdominal obesity (HR 1.30, 95% CI 1.23-1.38), and comorbidities: hypertension (HR 1.63, 95% CI 1.53-1.73), dyslipidemia (HR 1.35, 95% CI 1.29-1.42), chronic kidney disease (HR 1.52, 95% CI 1.44-1.61), cardiovascular disease (HR 1.71, 95% CI 1.58-1.86). Heavy (HR 0.67, 95% CI 0.61-0.74) and mild alcohol consumption (HR 0.78, 95% CI 0.74-0.83), overweight (HR 0.87, 95% CI 0.81-0.93) and obesity (HR 0.81, 95% CI 0.75-0.87), longer diabetes duration (≥ 5 years: HR 0.74, 95% CI 0.70-0.78), and using ≥ 3 oral hypoglycemic agents (HR 0.84, 95% CI 0.79-0.90) were associated with decreased AAA risk, while insulin use was associated with a marginally increased risk (HR 1.09, 95% CI 1.00-1.18). Among the oral hypoglycemic agents, metformin (HR 0.95, 95% CI 0.90-1.00), thiazolidinedione (HR 0.87, 95% CI 0.79-0.97), and sulfonylurea (HR 0.88, 95% CI 0.83-0.93) were associated with decreased risk of AAA.

CONCLUSIONS

Although diabetes is associated with decreased AAA risk, those with comorbid cardiometabolic diseases, abdominal obesity, and smoking history should be aware of increased AAA risk. Further studies are warranted to verify the potential use of oral hypoglycemic agents for reducing AAA risk.

Association between diabetes status and long-term outcomes following open and endovascular repair of infrarenal abdominal aortic aneurysms

OBJECTIVE

Current literature reports conflicting findings regarding the effect of diabetes mellitus (DM) on outcomes of abdominal aortic aneurysm (AAA) repair. In this study we examined the effect of DM and its management on outcomes after open AAA repair (OAR) and endovascular AAA repair (EVAR).

METHODS

We identified all patients undergoing OAR or EVAR for infrarenal AAA between 2003 and 2018 in the Vascular Quality Initiative registry data linked with Medicare claims. We excluded patients with missing DM status. Patients were stratified by their preoperative DM status, and then further stratified by DM management: dietary, noninsulin antidiabetic medications (NIMs), or insulin. Outcomes of interest included 1-year aneurysm sac dynamics, 8-year aneurysm rupture, reintervention, and all-cause mortality. These outcomes were analyzed with the χ2 test, Kaplan-Meier methods, and multivariable Cox regression analyses.

RESULTS

We identified 34,021 EVAR patients and 4127 OAR patients, of whom 20% and 16% had DM, respectively. Of all DM patients, 22% were managed by dietary management, 59% by NIM, and 19% by insulin. After EVAR, DM patients were more likely to have stable sacs, whereas non-DM patients were more likely to have sac regression at 1 year. Compared with non-DM, DM was associated with a significantly lower risk for 8-year rupture in EVAR (EVAR hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.51-0.92). Compared with non-DM, NIM was associated with lower risk of rupture within 8-years for both EVAR and OAR (EVAR HR, 0.64; 95% CI, 0.44-0.94; OAR HR, 0.29; 95% CI, 0.41-0.80), whereas dietary control and insulin had a similar rupture risk compared with non-DM. However, compared with non-DM, DM was associated with a higher risk of 8-year all-cause mortality after EVAR and OAR (DM vs non-DM: EVAR HR, 1.17; 95% CI, 1.11-1.23; OAR HR, 1.16; 95% CI, 1.00-1.36). After further DM management substratification, compared with non-DM, management with NIM and insulin were associated with a higher 8-year mortality in EVAR and OAR (EVAR: NIM HR, 1.12; 95% CI, 1.05-1.20; insulin: HR, 1.40; 95% CI, 1.26-1.55; OAR: NIM HR, 1.27; 95% CI, 1.06-1.54; and insulin: HR, 1.57; 95% CI, 1.15-2.13). Finally, there was a similar risk of reintervention across the DM and non-DM populations for EVAR and OAR.

CONCLUSIONS

DM was associated with a lower adjusted risk of rupture after EVAR as well as OAR in patients managed with NIM. Nevertheless, just as in patients without AAA, preoperative DM was associated with a higher adjusted risk of all-cause mortality. Further study is needed to evaluate for differences in aneurysm-related mortality between DM and non-DM patients, and studies are planned to evaluate the independent effect of NIM on aneurysm-related outcomes.

Diabetes and Abdominal Aortic Aneurysm: Is the Protective Effect on AAA Due to Antidiabetic Medications Alone, Due to the Disease Alone, or Both?

Diabetes is a metabolic disease that may result in multiple microvascular and macrovascular diseases. Interestingly, many studies have demonstrated the inverse relationship between diabetes and the development and expansion of abdominal aortic aneurysm (AAA). One hypothesis is that the aortic wall stiffness resulting from hyperglycemia and advanced glycation end products could delay the development and growth of AAA. Other studies have proposed that the concurrent use of antidiabetic medications which promote anti-inflammatory cytokines while hindering pro-inflammatory cytokines may potentially be the reason for this protective effect of diabetes on AAA. Contrastingly, the presence of diabetes has been found to have a negative effect on the outcome of AAA following its repair which may be due to elevated blood glucose negatively affecting the healing process. The current literature has also demonstrated the negative impact of the use of fluoroquinolones on AAA. This comprehensive review critically reviewed and summarized the role of diabetes, anti-diabetes medications and fluoroquinolones on AAA, and on the effect of diabetes and certain anti-diabetes medications on outcomes following its repair.

Implicit screening of abdominal aortic aneurysms among veterans using lumbar spine MRI

BACKGROUND

Early detection of abdominal aortic aneurysms (AAAs) is critical given the high morbidity and mortality of a ruptured aneurysm. Screening ultrasound is recommended for men 65 and 75 years of age with a smoking history. However, studies have shown that the rate of ultrasound screening is low and that implicit AAA screening by abdominal imaging studies that were not originally intended for AAA screening can play a major role in AAA detection.

OBJECTIVE

The main objective was to evaluate the role of lumbar spine MRIs as an implicit AAA screening study by assessing the detection rate of AAAs in a broader cohort of veterans that included screening and non-screening populations.

METHODS

4085 consecutive lumbar spine MRIs from our institution between 2/2020 and 9/2023 were retrospectively reviewed. Each study was labeled AAA present, AAA not present, or indeterminate by radiologists. The correlation between the presence of AAAs and cardiovascular risk factors was assessed using multinomial logistic regression.

RESULTS

AAAs were present in 89 studies (2.2 %) from 80 patients (mean age 75.8 (56-93), M:F 10:0) and absent in 3935 cases (96.3 %) from 3310 patients (mean age 61.7 (19-100), M:F 9:1). Indeterminate cases (n = 61, 1.5 %) were mainly due to incomplete visualization (70.5 %). Mean AAA size was 3.6 cm with most AAAs (n = 43) smaller than 3.5 cm. Sixteen AAAs were 3.5-3.9 cm, 16 between 4 and 4.9cm, and 6 between 5 and 5.9 cm. Artifact precluded measurements in 8 cases. Among the AAA-positive cases, 20 had no prior documentation of AAA. Twenty-one patients with AAAs would not have met the criteria for the routine AAA screening ultrasound. Higher rates of hypertension, hyperlipidemia, and smoking were observed for the AAA cohort at 78.8 % (OR 2.037, CI 1.160-3.576, P = .013), 82.5 % (2.808, 1.543-5.110, P < .001), and 75 % (3.340, 1.979-5.638, P < .001), respectively, compared to the matched no-AAA cohort (58.2 %, 57.6 %, and 50.8 %; n = 2055).

CONCLUSION

Lumbar spine MRI is a valid modality for implicit screening of AAAs.

CLINICAL IMPACT

Those interpreting lumbar spine MRIs should be vigilant about assessing for AAAs, especially in men with a history of hypertension, hyperlipidemia, or tobacco smoking.

Development of a comorbidity index for patients undergoing abdominal aortic aneurysm repair

BACKGROUND

Endovascular aneurysm repair (EVAR) and open surgical repair (OSR) are two modalities to treat patients with abdominal aortic aneurysm (AAA). Alternative to individual comorbidity adjustment, a summary comorbidity index is a weighted composite score of all comorbidities that can be used as standard metric to control for comorbidity burden in clinical studies. This study aimed to develop summary comorbidity indices for patients who underwent AAA repair.

METHODS

Patients who went under EVAR or OSR were identified in National Inpatient Sample (NIS) between the last quarter of 2015 to 2020. In each group, patients were randomly sampled into experimental (2/3) and validation (1/3) groups. The weights of Elixhauser comorbidities were determined from a multivariable logistic regression and single comorbidity indices were developed for EVAR and OAR groups, respectively.

RESULTS

There were 34,668 patients underwent EVAR (2.19% mortality) and 4792 underwent OSR (10.98% mortality). Both comorbidity indices had moderate discriminative power (EVAR c-statistic, 0.641; 95% confidence interval [CI], 0.616-0.665; OSR c-statistic, 0.600; 95% CI, 0.563-0.630) and good calibration (EVAR Brier score, 0.021; OSR Brier score, 0.096). The indices had significantly better discriminative power (DeLong P <.001) than the Elixhauser Comorbidity Index (ECI) (EVAR c-statistic, 0.572; 95% CI, 0.546-0.597; OSR c-statistic, 0.502; 95% CI, 0.472-0.533). For internal validation, both indices had similar performance compared with individual comorbidity adjustment (EVAR DeLong P = .650; OSR DeLong P = .431). These indices demonstrated good external validation, exhibiting comparable performance to their respective validation groups (EVAR DeLong P = .891; OSR DeLong P = .757).

CONCLUSIONS

ECI, the comorbidity index formulated for the general population, exhibited suboptimal performance in patients who underwent AAA repair. In response, we developed summary comorbidity indices for both EVAR and OSR for AAA repair, which were internally and externally validated. The EVAR and OSR comorbidity indices outperformed the ECI in discriminating in-hospital mortality rates. They can standardize comorbidity measurement for clinical studies in AAA repair, especially for studies with small samples such as single-institute data sources to facilitate replication and comparison of results across studies.

Insulin Dependence is Associated with Poor Long-Term Outcomes Following AAA Repair

BACKGROUND

While prior studies have confirmed the protective effect of diabetes on abdominal aortic aneurysm (AAA) development, much less is known about the effect of diabetes, and in particular insulin dependence, on outcomes following AAA repair. In this study, we aim to evaluate the role of insulin-dependent diabetes on short-term and long-term outcomes following open and endovascular AAA repair.

METHODS

The Vascular Implant Surveillance and Interventional Outcomes Network (VISION), a registry linking the Vascular Quality Initiative (VQI) data with Medicare claims, was queried for patients who underwent open or endovascular AAA repair from 2011 to the present. Exclusion criteria were unknown diabetes status, prior aortic intervention, maximum aneurysm diameter <45 mm at presentation, and Medicare Advantage coverage due to inconsistent follow-up. Patients were stratified based on diabetes status (no diabetes versus diabetes) and insulin dependence (no diabetes or non-insulin-dependent diabetes versus insulin-dependent diabetes).

RESULTS

Of the 38,437 cases in the VISION endovascular aortic aneurysm (EVAR) and open aortic aneurysm repair (OAR) databases, 21,943 met inclusion criteria. Perioperative outcomes after OAR were comparable between diabetic and nondiabetic patients. However, diabetic patients undergoing EVAR were significantly more likely to have a postoperative myocardial infarction (1.0% vs 0.6%, P = 0.04) and have a 30-day readmission (10.9% vs 8.8%, P < 0.001). Insulin-dependent diabetic patients were more likely to require a 30-day readmission after OAR (24.5% vs 13.5%, P = 0.02) and EVAR (15.1% vs 9.0%, P < 0.001); however, only insulin-dependent diabetes mellitus (IDDM) patients undergoing EVAR experienced higher rates of postoperative myocardial infarction (1.9% vs 0.7%, P < 0.01). After propensity score matching, patients with IDDM undergoing EVAR were additionally at increased risk of mortality at 1-year, 3-year, and 5-year follow-up with the highest risk occurring at the 1-year mark (hazard ratio 1.79, P < 0.0001), while IDDM patients undergoing OAR were only at a significantly increased risk of mortality at 5-year follow-up (hazard ratio 1.90, P = 0.01).

CONCLUSIONS

Patients with insulin-dependent diabetes have greater than 14% one-year mortality following open or endovascular aneurysm repair, compared to 8% for all others. Our findings raise questions about whether insulin-dependent diabetics should have a higher size threshold for prophylactic repair, although further studies are needed to address this question and consider the influence of glycemic control on these outcomes.

Molecular bases of comorbidities: present and future perspectives

Co-occurrence of diseases decreases patient quality of life, complicates treatment choices, and increases mortality. Analyses of electronic health records present a complex scenario of comorbidity relationships that vary by age, sex, and cohort under study. The study of similarities between diseases using 'omics data, such as genes altered in diseases, gene expression, proteome, and microbiome, are fundamental to uncovering the origin of, and potential treatment for, comorbidities. Recent studies have produced a first generation of genetic interpretations for as much as 46% of the comorbidities described in large cohorts. Integrating different sources of molecular information and using artificial intelligence (AI) methods are promising approaches for the study of comorbidities. They may help to improve the treatment of comorbidities, including the potential repositioning of drugs.

Novel pharmacological approaches in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a severe vascular disease and a major public health issue with an unmet medical need for therapy. This disease is featured by a progressive dilation of the abdominal aorta, boosted by atherosclerosis, ageing, and smoking as major risk factors. Aneurysm growth increases the risk of aortic rupture, a life-threatening emergency with high mortality rates. Despite the increasing progress in our knowledge about the etiopathology of AAA, an effective pharmacological treatment against this disorder remains elusive and surgical repair is still the unique available therapeutic approach for high-risk patients. Meanwhile, there is no medical alternative for patients with small aneurysms but close surveillance. Clinical trials assessing the efficacy of antihypertensive agents, statins, doxycycline, or anti-platelet drugs, among others, failed to demonstrate a clear benefit limiting AAA growth, while data from ongoing clinical trials addressing the benefit of metformin on aneurysm progression are eagerly awaited. Recent preclinical studies have postulated new therapeutic targets and pharmacological strategies paving the way for the implementation of future clinical studies exploring these novel therapeutic strategies. This review summarises some of the most relevant clinical and preclinical studies in search of new therapeutic approaches for AAA.