Ethnic Disparities With Type B Aortic Dissection
Is there a difference in outcomes after endovascular intervention in patients with complicated type B aortic dissection (TBAD) based on ethnicity and blood pressure control?
One hundred and twenty-six patients who underwent endovascular procedures for complicated TBAD at a single-institution quaternary referral center between 2012 and 2016 were retrospectively analyzed. Patients self-identified as African American (n = 53), white (n = 70), and Asian (n = 3). African American and white patients were compared on a number of variables, including age, ethnicity, insurance type, blood pressure, comorbidities, number of previous interventions, and number of antihypertension medications they were taking before intervention. Primary outcomes were survival and need for reintervention.
In a series of 126 patients with complicated TBADs treated with thoracic endovascular repair, African Americans had similar 5-year survival, but poorer hypertension control and more interventions than other ethnic groups. Kaplan-Meier estimates for survival for African Americans vs. whites were 94% vs. 89%, 91% vs. 83%, 89% vs. 79%, and 89% vs. 76% at 30 days, 1 year, 3 years, and 5 years, respectively (p = 0.05). African Americans were younger overall (52.5 ± 11 years) vs. whites (63.7 ± 14.7 years; p < 0.0001). African Americans required a significantly greater number of reinterventions (p = 0.007). They also had higher rates of chronic kidney disease (p = 0.01), smoking (p = 0.03), and cocaine use (p = 0.02) and were more likely to be on Medicaid (p = 0.02). Hypertension was poorly controlled in both groups, with the percentage of patients with uncontrolled hypertension (systolic >140 mm Hg) preoperatively, postoperatively, and 30 days after intervention at 32%, 32%, and 39%.
Optimal medical therapy is difficult to achieve in all groups. More aggressive medical management is needed, particularly more so in African Americans, which may in turn decrease the number of interventions and potentially improve long-term survival.
Healthcare disparities are often at least partly attributable to differences in access to care (and related socioeconomic and geographic factors). This retrospective analysis from a self-proclaimed “quaternary referral center” of patients treated with an endovascular procedure, therefore, provides only part of the picture. Given the complexity of the presentation of TBAD and need for anatomic imaging for definitive diagnosis, it is probable that many patients face challenges to timely diagnosis and implementation of appropriate medical management. Because patients included in this analysis managed to navigate to procedural intervention at a high volume center, the observed disparities likely represent only the tip of the iceberg.
Several aspects of this analysis limit generalizability of the findings. First, the single-center, retrospective approach misses post-procedure events treated at other centers and health systems, making it likely that observed event rates (and, conversely, event-free survival) are conservatively biased. Second, the approach to defining the hypertension-related variables and outcomes was not described in sufficient detail to provide an overview of long-term hypertension control. Retrospective collection of blood pressure data from the electronic medical record offers the abstractor a variety of options because this variable is usually available from both arms and collected multiple times per day during an inpatient stay. The methods did not include how the investigators approached selecting which value(s) were included for analysis, did not adjust for within-patient correlation for blood pressure as a repeated measure, and did not include blood pressures recorded outside of healthcare visits. Moreover, the number of antihypertensive agents is an increasingly crude indicator of blood pressure control in the modern era where angiotension-converting enzyme inhibitors, angiotensin-receptor blockers, diuretics, and other agents may be implemented for risk reduction related to comorbidities (such as diabetes or congestive heart failure) without absolute necessity for blood pressure control. Third, the lack of a medical management comparison group or specific criteria for endovascular intervention make it challenging to discern how patients were selected for procedural intervention, or what percentage were managed medically.
Additionally, the authors report a higher rate of cocaine use among African Americans, but do not comment on their criteria for performing drug screens. It would be interesting to know if all patients were screened for cocaine regardless of their race, gender, or ethnicity. This information would be important to interpret whether the observed difference reflects biased screening criteria.
These limitations aside, the observed disparities were clinically significant and should be relevant to all providers who care for patients with type B dissection. Most physicians probably would not hypothesize that the younger presentation and increased number of repeat interventions among African Americans would be associated with superior survival, as reported. It is important to note, however, that less than half the cohort was at risk beyond 2 years, limiting conclusions that can be drawn from this apparent paradox. Nonetheless, the high prevalence of previous interventions (i.e., before the index procedure used as the inclusion criterion for this analysis) as well as repeat interventions supports the notion that type B dissections should be approached as a chronic disease where a single procedure often falls short of being curative. The importance of multi-specialty, team-based approaches to management of these patients, including mutually understood goals for outpatient monitoring and treatment of hypertension, should be emphasized as an opportunity to understand and mitigate disparities.
Keywords: African Americans, Aneurysm, Dissecting, Antihypertensive Agents, Blood Pressure, Cardiology Interventions, Cocaine, Endovascular Procedures, Hypertension, Outcome Assessment (Health Care), Primary Prevention, Renal Insufficiency, Chronic, Smoking, Vascular Diseases
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