April 7, 2021

Study Finds Significant Sex-Related Disparities in AAA and PAD Treatment in the United States

April 7, 2021—Using a large national data set to explore sex-related disparities in the management of abdominal aortic aneurysm (AAA), carotid artery stenosis (CAS), and peripheral artery disease (PAD), McGinigle et al found that females were significantly less likely to undergo intervention for AAA and PAD as compared with males, even after accounting for sex-specific prevalence estimates. Females were also less likely to undergo endovascular surgery for AAA and CAS but more likely to have their PAD treated endovascularly. Results of this study were published online ahead of print in Journal of Vascular Surgery.

Key Findings

As compared with males, females were 25% and 30% less likely to undergo intervention for AAA and PAD, respectively.
Treatment rates for CAS were comparable between females and males.
Females were less likely to undergo endovascular aneurysm repair and carotid stenting, but more likely to undergo endovascular intervention for PAD.

The investigators used the Healthcare Cost and Utilization National Inpatient Sample to identify all adult patients who were hospitalized and underwent vascular surgery for AAA, CAS, or PAD between January 1, 2000 and December 31, 2016. ICD-9-CM and ICD-10-CM codes were used to capture diagnoses and procedures of interest.

The number of United States adults with AAA, CAS, and PAD were calculated using United States Census data stratified by sex and sex-specific population disease prevalence estimates from the National Institutes of Health and Agency for Healthcare Research and Quality. Poisson regression was used to estimate sex-stratified rates of surgery and incidence rate ratios (IRRs), and multivariable logistic regression was used to evaluate differences in endovascular versus open surgery.

There were 1,021,684 hospitalizations for AAA, CAS, and PAD from 2000 to 2016. Overall, AAA accounted for 13% (21% female, 79% male), CAS accounted for 40% (42% female, 58% male), and PAD accounted for 47% (42% female, 58% male) of operations. At the time of surgery, females were older than males (median age, 71.3 vs 69.7 years) and less likely to have private insurance (18% vs 23%). There were minimal differences seen across race/ethnicity, comorbidities, and hospital characteristics.

After accounting for disease prevalence, females were 25% less likely to undergo surgery for AAA and 30% less likely to undergo surgery for PAD as compared with males (IRR, 0.76; 95% CI, 0.75-0.76 and IRR, 0.69; 95% CI, 0.69-0.69, respectively), but the treatment rates for CAS were comparable between females and males (IRR, 0.96; 95% CI, 0.95-0.96). Results were consistent over time. As compared with males, females were less likely to undergo an endovascular versus open procedure for AAA or CAS (odds ratio [OR], 0.55; 95% CI, 0.53-0.57 and OR, 0.94; 95% CI, 0.91-0.94) but more likely to undergo an endovascular procedure for PAD (OR, 1.28; 95% CI, 1.26-1.30). These results were consistent over time as well.

As noted by the authors, there are certain limitations to this study, including potential variability in sex-specific prevalence estimates for AAA, CAS, and PAD; use of a large national data set that captures a sample of inpatient hospitalizations, not outpatient; and coding discrepancies potentially caused by the switch from ICD-9-CM to ICD-10-CM in 2015.

Given the results of this study, future randomized trials should look to address endovascular and open treatment strategies in females, and additional studies into sex-specific screening recommendations, comorbidity management, and objective thresholds are needed to address the undertreatment of AAA and PAD in females, noted the investigators.

ENDOVASCULAR TODAY ASKS….

Lead author Katharine McGinigle, MD, MPH, with the University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, was asked to elaborate on some of the study results:

Prevalence estimates for PAD are the same for males and females, yet this study found that females were less likely to undergo intervention for PAD. What are some possible explanations for this difference?

PAD is underdiagnosed in general, but even with objective data like abnormal ankle-brachial indices, we know that the difference in the way that females and males describe their symptoms influences our ability to make a correct diagnosis and move on to a treatment plan. Women are more likely to have atypical lower extremity symptoms instead of textbook claudication, are referred later for specialty care, and are more likely to have chronic limb-threatening ischemia at the time of diagnosis. Another study has demonstrated that females provide a more positive subjective evaluation of themselves while having worse objective walking test results compared to males being considered for the same interventions. PAD in females should be approached with a high index of suspicion, aggressive risk factor modification, and acknowledgment that there is bias against offering intervention.

What other factors might compound with female sex to contribute to further disparities?

Underrepresentation of females in clinical trials contributes to the lack of awareness of vascular disease presentation, treatments, and outcomes in this population. Public health guidelines for screening for vascular disease, particularly AAA, are more limited for females compared to males. Furthermore, from a social perspective, women, especially women who are minorities, are more likely to face barriers in accessing health care.

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