Gender is not an independent Risk Factor for Long Term Survival after EVAR
William P Shutze, Sr.1, Paul Dhot2, Moses Forge2, Alejandro Salazar2, Gerald O Ogola3
1The Heart Hospital Baylor Plano, Plano, TX;2Texas Vascular Associates, Plano, TX;3Office of the Chief Quality Office, Baylor Scott and White Health, Dallas, TX
Background We proposed to assess the gender based differences in: age, BMI, race , comorbidities, AAA diameter, the aortic neck and iliac arteries in patients undergoing endovascular AAA repair (EVAR) and evaluate the impact of these variables on survival after EVAR.
MethodsBetween 2002-2009 there were 464 EVAR procedures performed at our institution and 336 patients had an adequate digital preoperative CT scan of the AAA available and complete descriptive and survival data. The scans were sent to a core imaging lab (M2S, Lebanon, N.H.) which extracted aortic neck length, diameter, angulation, calcification and iliac length, tortuosity, angulation and calcification, and AAA diameter from these scans. These measurements were returned in a spreadsheet to which we added the patient’s information. Patient mortality was assessed using the Social Security deathmaster file. Survival time was defined by number of days between date of surgery and date of death. Kaplan-Meier estimation was used to generate survival curves. Multivariable Cox proportional hazards regression model with restricted cubic splines (with 3-knots) on continuous covariates was performed to assess association between five-year mortality and patients’ sex while adjusting for other covariates (age, race, BMI, tobacco use history, comorbidities, aortic neck, iliac artery and AAA variables).
Results
There were 278 males and 58 females in the total group. The average age for the males was 73 years compared to 77 for the females (p=.0005). Whites accounted for 255 (91.7%) of the males and 49 (84.5%) of the females (p=.87). The average BMI was 25.2 in the males and 23.1 in the females (p=.006). The female and male groups were comparable for comorbities except for CAD where the males had a higher frequency of CABG (p=.02) and PCI (p=.03). The anatomic differences are detailed in Table 1. Males (43.5%) were more likely than females (22.4%) to have EVAR performed within the device IFU guidelines (p=.0002). The five-year survival in females who were treated for endovascular AAA repair was 49% as compared to males with 73%. In multivariate analysis, sex was not statistically significant. Increase in age, iliac artery length, CHF, dialysis and BMI less than 25 kg/m2 or greater than 30 kg/m2 were significantly associated with shorter survival.
Conclusions Significant anatomic differences and survival exist between males and females undergoing EVAR. Women present at an older age but with similar AAA diameter to males. Females have more hostile anatomy in general and have a significantly reduced survival than males after EVAR. After controlling for comorbidities, aortic neck and iliac artery anatomy, gender does not appear to be an independent predictor for survival.
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| Anatomic variables | All | Male | Female | P-value |
| Proximal aortic neck angle | 142.9 ± 15.1 | 143.8 ± 14.7 | 138.3 ± 16.3 | 0.01 |
| Proximal aortic neck diameter | 22.7 ± 3.3 | 23.1 ± 3.2 | 20.8 ± 3.3 | <0.0001 |
| Proximal aortic neck diameter 15 mm inferiorly | 24.2 ± 3.5 | 24.6 ± 3.4 | 22.4 ± 3.6 | <0.0001 |
| Aortic neck calcification score | 0.6 ± 0.8 | 0.6 ± 0.8 | 0.6 ± 0.7 | 0.76 |
| Aortic neck length | 20.9 ± 12.6 | 21.9 ± 12.5 | 16.1 ± 11.9 | 0.001 |
| Iliac artery length | 60.2 ± 18.0 | 61.2 ± 17.8 | 55.3 ± 18.4 | 0.01 |
| Left common iliac artery diameter | 14.0 ± 4.0 | 14.5 ± 4.1 | 11.2 ± 1.8 | <0.0001 |
| Right common iliac artery diameter | 15.2 ± 5.4 | 15.9 ± 5.6 | 11.9 ± 2.2 | <0.0001 |
| Iliac artery angle | 114.1 ± 14.6 | 113.5 ± 14.6 | 117.1 ± 14.6 | 0.08 |
| Table 2 Cox proportional hazard ratio with 95% confidence interval for 5-year survival of endovascular AAA repair patients | ||
| Risk factor | Hazard Ratio (95% CI) | P-value |
| Female sex | 1.198 | .4826 |
| Age (years) | 1.048 | 0.0012 |
| BMI | 0.821 | <.0001 |
| Aortic neck length | 1.013 | 0.6265 |
| Iliac artery length | 1.015 | 0.0123 |
| CHF | 2.005 | 0.0166 |
| COPD | 1.460 | 0.1106 |
| Renal dysfunction dialysis | 1.981 | 0.0180 |
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