A registry-based rationale for discrete intervention thresholds for open and endovascular elective abdominal aortic aneurysm repair in female patients Stephanie M. Tomee, BS,a Niki Lijftogt, MD,a Anco Vahl, MD, PhD,b Jaap F. Hamming, MD, PhD,a and Jan H. N. Lindeman, MD, PhD,a Leiden and Amsterdam, The Netherlands
ABSTRACT Objective: An evidence-based consensus for a female-specific intervention threshold for abdominal aortic aneurysms (AAAs) is missing. This study aims to analyze sex-related differences in the epidemiology of ruptured AAA to establish an intervention threshold for women. Methods: The Dutch Surgical Aneurysm Audit (DSAA) is a compulsory, nation-wide registry of AAA repairs in The Netherlands. All patients with emergency or elective AAA repair between January 1, 2013, and December 31, 2015, were included in the analysis. The main outcomes were age, sex, AAA diameter at time of rupture, and 30-day postoperative mortality. Results: A total of 1561 ruptured AAA repairs (14.7% women) and 7063 cases of elective AAA repair (13.7% women) were included in the analysis. Women had significantly smaller mean 6 standard deviation AAA diameter at time of rupture than men; 70.5 6 14.4 mm and 78.6 6 17.5 mm, respectively. In male patients, 8% of ruptures occurred at diameters below the 55 mm intervention threshold. The female equivalent of this eighth percentile is 52 mm. Female patients had significantly higher 30-day mortality after emergency repair, namely, 33% for women versus 24.2% for men, but were also significantly older, mean 6 standard deviation age 76.7 6 7.1 years and 73.9 6 8.3 years for women and men, respectively. Correcting for age reduced the 30-day mortality risk for women after ruptured AAA repair from 1.53 (95% confidence interval, 1.14-2.04) to 1.27 (95% confidence interval, 0.92-1.73). Outcome after open elective repair was significantly worse for women compared with men, with a 30-day mortality of 7.97% 30 for women and 4.27% for men (P < .01). Conclusions: The equivalent of the 55-mm intervention threshold for elective endovascular AAA repair in men is 52 mm in women. The almost doubled mortality risk for elective open repair in women implies that the optimal point for open repair is at higher diameters, very possibly at least 55 mm. (J Vasc Surg 2017;-:1-5.)
Abdominal aortic aneurysm (AAA) is particularly prevalent in men.1 Based on solid prospective clinical data,2-5 current practice guidelines recommend conservative follow-up until the maximum aneurysm diameter reaches 55 mm, at which point surgical intervention should be considered.6 On the basis of their smaller baseline aortic diameter, reported earlier ruptures, and less favorable outcome after repair, it has been argued that women qualify for repair at diameters of less than 55 mm.2,7,8 A report using Medicare data of more than 20,000 ruptured AAA (RAAA) repairs showed that after emergency repair women have higher 30-day mortality, worse long-term survival, and higher readmission rates compared with
men.9 Yet, a concrete, evidence-based consensus with respect to a sex (female)-specific intervention diameter is missing. In fact, the clinical practice guidelines of the European Society for Vascular Surgery state that, “there still remains some uncertainty about the management of small aneurysms in females.”6 The Dutch Surgical Aneurysm Audit (DSAA) is a nation-wide, compulsory registry in a country without an AAA screening program. As such, it allows for a population-based analysis of the putative sex-related differences in the epidemiology of RAAA. The purpose of this study is to provide a rationale for an AAA elective intervention threshold specifically for women on the basis of registry data.
METHODS From the Department of Vascular Surgery, Leiden University Medical Center, Leidena; and the Department of Vascular Surgery, Onze Lieve Vrouwe Gasthuis, Amsterdam.b Author conflict of interest: none. Correspondence: Jan H.N. Lindeman, MD, PhD, Department of Surgery, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands (e-mail:
[email protected]). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2017 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jvs.2017.07.123
All patients with a RAAA registered in the DSAA between January 1, 2013, and December 31, 2015, in The Netherlands were included for primary analysis. The DSAA registration is mandatory for medical centers that perform a minimum of 20 AAA repairs per year. Registrations are available for sex, date of birth, diameter at time of rupture, type of procedure, mortality, and preoperative creatinine levels. Data on imaging modalities (eg, computed tomography [CT] scans or ultrasound examination) is not available in the DSAA. Yet, considering the need of CT for surgical workup, the majority of 1
2
Journal of Vascular Surgery
Tomee et al
---
measurements of AAA diameter after rupture will be CT based. Data for elective repair registered in the DSAA for the same time period was used as a reference with respect to postoperative outcome. All registry data are anonymized and cannot be traced back to individual patients or medical centers. Patient informed consent was therefore not obtained. This study proposal was approved by the scientific board of the DSAA. Statistical analysis was done using SPSS 23 (IBM, Amsterdam, The Netherlands). Continuous variables were reported as mean 6 standard deviation, and t tests were used to test for significant differences. Categorical data were reported in proportions and statistical significance was tested with c2 and 95% confidence intervals (CIs). Putative associations between sex, age, body mass index, American Society of Anesthesiologist scores, type of procedure (open or endovascular aneurysm repair [EVAR]), estimated glomerular filtration rate, AAA diameter, and 30-day postoperative mortality were explored through univariate logistic regression analysis, and the significant factors included in a multivariate model. Factors included in the univariate analysis were chosen on basis of the clinical relevance. P < .05 was considered significant.
2017
ARTICLE HIGHLIGHTS d
d
d
Type of Research: Retrospective review of a compulsory national registry (Dutch Surgical Aneurysm Audit [DSAA]) Take Home Message: In 8624 abdominal aortic aneurysm repairs, the mean diameter of ruptured abdominal aortic aneurysms was significantly smaller in women than in men (70.5 mm vs 78.6 mm); 8% of ruptured abdominal aortic aneurysms were less than 52 mm in size in women and less than 55 mm in men. Mortality of elective repair was significantly higher in women than in men (7.97% vs 4.27%). Recommendation: This study suggests that women should undergo elective repair for aneurysms 52 mm in size, but only if the mortality of elective repair is further reduced.
RESULTS The DSAA registry database contains data from 9506 AAA repairs that were performed between January 1, 2013, and December 31, 2015, in The Netherlands. These data cover nearly all procedures performed in The Netherlands. For the primary analysis, we selected all 1719 patients in the registry who underwent emergency repair because of a ruptured aneurysm. Cases with missing entries on sex and/or age were excluded from the analysis. In addition, only cases with reported aneurysm sizes greater than 35 mm were selected to avoid any coding errors (Fig 1). Potential sex-specific differences in elective repair risk were evaluated in the 7063 elective AAA repair cases in the registry. We identified 1561 evaluable emergency AAA repairs, the majority of which was by open repair (63.7%). Approximately 14.7% of the emergency repairs and 13.7% of elective repairs involved women (P ¼ .31; Table I). The percentages EVAR or open repair in an emergency setting were similar for men and women. Among 7063 elective procedures, women underwent significantly more often open operative procedures (31.4%) compared with men (22.5%; P < .0001). Fig 2 shows the distribution of maximum AAA diameters at the time of emergency repair for men and women. Compared with men, the AAA size distribution for women was shifted toward the left with a mean 6 standard deviation AAA rupture diameter in
Fig 1. Flow chart of patients receiving undergoing abdominal aortic aneurysm (AAA) repair registered in the Dutch Surgical Aneurysm Audit (DSAA) between January 1, 2013, and December 31, 2015.
women of 70.5 6 14.4 mm versus 78.6 6 17.5 mm in men (P < .0001). Because AAA growth rate increases with AAA diameter, the 8-mm difference in mean AAA size at the time of rupture does not translate in an 8-mm lower intervention threshold. To address this point, we used the RAAA size distribution for men in the DSAA to estimate a female equivalent of the male 55-mm intervention threshold. This consensus intervention threshold reflects a tradeoff between elective repair risks, costs, and the risk of rupture. The AAA size-at-rupture distribution showed that, in men, 8% of all ruptures occur at sizes of less than the 55-mm threshold. We used this percentile to estimate the female equivalent of the male 55-mm intervention threshold. The corresponding female equivalent of this 8th percentile is 52 mm. This size equivalent assumes comparable surgical riskbenefit ratios for men and women. Emergency repair in women is associated with a significantly higher 30-day
Journal of Vascular Surgery Volume
-,
Number
Tomee et al
3
-
Table I. Patient characteristics of patients receiving emergency aneurysm repair (RAAA) and elective aneurysm repair (elective) RAAA
Elective
Patient characteristics
Male
Female
P
Male
Female
Age, mean (SD), years
73.9 (8.3)
76.7 (7.1)
