Racial and Ethnic Disparities in the Presentation and Outcome of Patients with Thoracic Aortic Aneurysms

1. Introduction

Thoracic aortic diseases encompass a wide spectrum of conditions, with thoracic aortic aneurysms (TAA) and dissections being the most critical¹. TAAs often remain asymptomatic until a catastrophic event such as a dissection or rupture occurs, with mortality rates exceeding 90% without intervention². Hence, early detection and appropriate (surgical) intervention are imperative. Current American and European aortic guidelines recommend surgical repair of the aortic wall in patients with an ascending aorta diameter ≥ 5.5 cm, with a lower threshold of 5.0 cm advised in the presence of risk factors^4,5.

Although the exact pathogenesis of TAA is not yet fully understood, several pathological mechanisms such as abnormalities in smooth muscle cell function and differentiation, influenced by their embryonic origins, have been described ^6-8. Clinical risk factors have also been explored in the development of TAAs. While sex-specific variations in TAAs have been clearly documented^2,3,8, the influence of ethnic and racial disparities on TAAs remains underexplored partly due to significant heterogeneity in defining race and ethnicity worldwide. The impact of these disparities on the diagnosis and management of TAAs is crucial for accurate assessment of individual risk levels for a tailored approach. Improved personalized risk stratification is imperative to optimize diagnostic and therapeutic strategies for TAAs among diverse ethnic groups and to improve patient outcomes. Therefore, this study aims to provide a comprehensive summary of current research on racial and ethnic disparities in TAAs.

2. Materials and Methods

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with the objective of exploring racial and ethnic differences in the presentation and surgical outcomes of patients with TAAs¹⁰.

Search Strategy

A comprehensive systematic literature search was performed in PubMed to identify relevant studies published up to December 31st, 2023. Controlled search terms were utilized, focusing on two primary domains and encompassing all synonyms of the core terms: “aortic aneurysm” and “ethnicity”. Additionally, the reference lists of included articles were meticulously cross-checked to ensure no relevant literature was overlooked. For the complete search strategy see Table I.

Study Selection

Eligibility Criteria

Inclusion criteria were defined to encompass any empirical study involving patients with TAA that reported on at least two ethnic groups. Studies were included if they provided predictive values or outcomes such as mortality, readmission rates, or survival rates.

Due to the significant variability in the definition of race or ethnicity and the absence of universally accepted standards to for defining ethnic groups, our analyses primarily focused on the comparison of black and non-black individuals.

Exclusion criteria included review articles, case reports (or studies with a population of fewer than 15), meta-analysis, conference abstracts only published in abstract form, studies published languages other than English, and studies published prior to 2000.

Screening and Data Extraction

Title and abstract screening were performed by one author (N.B.) to identify potentially relevant articles. Full texts of eligible studies were then assessed according to the predetermined criteria. Data extraction was carried out using a standardized form, which captured information on study population, design, clinical presentation, and surgical outcomes. Separate columns were included for documenting clinical presentation and surgical outcomes for black and non-black patients (see Table II).

3. Results

3.1. Study Selection and Characteristics

A systematic review of the literature identified 138 unique records. Following title and abstract screening, 121 studies were excluded for not meeting the inclusion criteria, leaving 17 for full-text review. Of these, 4 focused on abdominal aneurysms (AAA) and 3 did not report on relevant outcomes, resulting in 10 studies being included in the final analysis ^11-20. See Figure 1 for the PRISMA flow diagram.

3.2. Baseline Characteristics

The included studies encompassed a total of 283,076 patients from diverse ethnic backgrounds, revealing significant variability in incidence and clinical presentation of TAA.

Black patients showed higher incidence of ruptured thoracic aortic aneurysms in black patients compared to non-black patients (7.3% vs. 4.4%; P=0.001)¹¹ among 15,305 patients undergoing TAA repair. Non-black patients tended to present at an older age compared to black patients (74.5 vs. 73.7 years; P=0.001)²³, a finding corroborated two other studies^14,19.

Black patients also exhibited higher Charlson comorbidity scores (1.51 vs. 0.92; P=0.001)¹¹, with higher rates of renal insufficiency (35.4% vs. 17.8%; P=0.001)¹⁹, hypertension (100% vs. 86.5%; P=0.034)¹⁹, and diabetes mellitus (18.8% vs. 4.5%; P=0.021)¹⁹, while non-black patients had higher rates of COPD (20.1% vs. 6.3%; P=0.003)¹⁹ and cardiac arrhythmia (20.6% vs. 10.1%; P=0.037)¹⁹.Two other studies supported these findings^13,18.

Non-black patients had larger aortic necks (28.2 mm vs. 23.8 mm; P=0.01)¹⁸ and a higher prevalence of females with TAA (33.8% vs. 19.3%; P=0.02)¹⁸. Conversely, two other studies reported a higher prevalence of females among black patients^14,20.

Murphy et al.¹⁶ noted that non-black patients had a higher proportion of elective surgeries (48%; P=<0.001), whereas black patients had a higher proportion of emergency surgeries (20%; P=<0.001). These findings were confirmed by the study of Yin et al.¹².

3.3. Surgical Outcome

Goodney et al.¹¹ reported on higher perioperative mortality rates when undergoing open surgery (14.4% vs. 6.8%; P<0.001) in black patients compared to non-black patients, with black ethnicity being a significant risk factor (OR: 2.0; 95% CI 1.5-2.5). However, black patients demonstrated better 5-year survival rates post-open repair (71% vs. 61%; P<0.001).

Overall mortality in black patients was higher (13.7% vs. 9.8%; P=<0.001)¹⁶ and significant racial differences in in-hospital mortality were found (P<0.0001)¹⁴. In line with these results, ribieras and colleagues reported on higher complication rates (34.3% vs. 17.4%; P=0.014) and conversion rates to open repair (2.9% vs. 0%; P=0.011) in black patients compared to non-black patients.

No significant differences in all-cause or in-hospital mortality between black and non-black patients were found in four studies^13,18-20. Although the study by Yin et al.¹² found no significant cause in overall 30-day mortality rate, after adjustment for demographics, comorbidities, and operative factors, black race was independently associated with a 56% lower 30-day mortality rate after thoracic endovascular aortic repair (TEVAR) (OR: 0.44; 95% CI 0.22-0.85; P=0.01). Johnston et al.¹⁵ also reported varied odds ratios for TEVAR performance across ethnic groups as outlined in Table II. Lastly, Vervoort et al. ¹⁸ showed a lower reintervention hazard ratio in black patients compared to white patients (HR: 0.7; P=0.01)¹⁸.

3.4. Figures, Tables and Schemes

Figure 1. Flowchart of selected articles according to the PRISMA statement.

Figure 1. Flowchart of selected articles according to the PRISMA statement.

4. Discussion

This review aimed to summarize current research on racial and ethnic disparities in the presentation and outcomes of TAAs in order to aid in the development of personalized risk stratification methods. Analysis of ten empirical studies focusing on the dichotomy between black and non-black individuals revealed that black patients with TAA more commonly exhibit comorbidities such as diabetes, heart failure, and renal insufficiency, whereas non-black patients often present with COPD, coronary artery disease, and cardiac arrhythmias. Black individuals tend to present at a younger age and face a nearly doubled risk of ruptured TAA at presentation compared to non-black individuals. Despite these differences, four studies found no significant disparity between the racial groups ^13,18-20. Our findings align with existing literature on abdominal aortic aneurysms and aortic dissections,^21-24 suggesting potential consistencies in racial impacts across various aortic conditions.

However, lack of standardization in defining race and ethnicity among studies pose considerable challenges. There is a need for consensus on these definitions to improve the reliability of research findings. Future research should address these inconsistencies and develop tailored risk assessment models that consider disparities in comorbidities between racial groups. A personalized risk stratification model could enhance the precision in predicting outcomes and improve preventive and therapeutic strategies for patients with TAA.

A reasonable suggestion would be to adopt standardized racial and ethnic categories, such as those defined by the National Institutes of Health (NIH)²⁵. These categories include American Indian or Alaska Native, Asian, Black or African American, Hispanic or Latino, Native Hawaiian or Other Pacific Islander, and White. The classification should prioritize self-reporting by individuals rather than assignment by observers, aligning with recommendations from recent research²⁶. This approach would facilitate consistency in defining and analysing racial disparities in the presentation and outcomes of thoracic aortic aneurysms (TAA), thereby enhancing the validity and comparability of research findings across studies.

In conclusion, this review demonstrates significant differences in the presentation and surgical outcomes of TAA between racial and ethnic groups. Recognizing these differences is essential for developing tailored interventions and improving outcomes for all patients, regardless of race or ethnicity. Further research is needed to uncover the underlying cause of these disparities and to refine risk stratification models accordingly.