Variation in the choice of elective surgical procedure for abdominal aortic aneurysm in Spain

Figures & data

Figure 1 Selection process for study inclusion.

Note: Patients diagnosed with unruptured AAA, undergoing EVAR or OSR with an elective admission during the study period 2002–2012.
Abbreviations: AA, aortic aneurysm; AAA, abdominal aortic aneurysm; EVAR, endovascular aneurysm repair; OSR, open surgical repair.

Table 1 Characteristics of patients undergoing elective surgical repair for unruptured AAA in Spanish hospitals between 2002 and 2012

	Included patients (N=16,737)
	n	%
Age (years)
Mean (SD)	71.4 (7.8)
Median (min–max)	72 (25–96)
Gender
Male	16,185	96.7
Female	552	3.3
Charlson Index
Mean (SD)	0.7 (0.98)
Median (min–max)	0 (0–10)
Type of intervention
EVAR	6,809	40.7
OSR	9,928	59.3
Surgical volumes for AAA repair per hospital through the study period
Mean (SD)	328.2 (159.25)
Median (min–max)	306 (1–682)
In-hospital mortality rates
Yes	601	3.6
No	16,136	96.4

Abbreviations: AAA, abdominal aortic aneurysm; EVAR, endovascular aneurysm repair; OSR, open surgical repair.

Figure 2 Volume of AAA surgeries performed in the hospitals participating in the study from 2002 to 2012, distribution of the two types of procedures and evolution of mortality.

Notes: (A) Number of surgical procedures performed at each participating hospital during the study period and the proportion of these interventions in each center. (B) EVAR as a proportion of surgical procedures to treat AAA from 2002 to 2012 at all participating hospitals. The mortality is also shown for the same period.
Abbreviations: AAA, abdominal aortic aneurysm; EVAR, endovascular aneurysm repair.

Table 2 Characteristics of patients undergoing surgical repair for AAA: OSR vs EVAR

	Included patients (N=16,737)
	EVAR (n=6,809)		OSR (n=9,928)		OR	95% CI	P-value
	n	%	n	%
Age
Mean (SD)	73.8 (7.4)		69.7 (7.6)		1.08	(1.07–1.08)	<0.001
Median (min–max)	75 (29–96)		71 (25–94)
Gender
Male	6,568	40.6	9,617	59.4	1	(0.96–1.35)	0.148
Female	241	43.7	311	56.3	1.13
Charlson Index					1.16	(1.13–1.20)	<0.001
Mean (SD)	0.8 (1.04)		0.6 (0.93)
Median (min–max)	0 (0–8)		0 (0–10)
Intervention volume per hospital throughout the period/100
Mean (SD)	341.2 (160.70)		319.2 (157.64)		1.09	(1.07–1.11)	<0.001
Median (min–max)	319 (1–682)		304 (1–682)

Abbreviations: AAA, abdominal aortic aneurysm; EVAR, endovascular aneurysm repair; OSR, open surgical repair.

Figure 3 Funnel plot: probability of in-hospital mortality and surgery by EVAR, according to the volume of procedures performed in the hospitals participating in the study.

Abbreviations: AAA, abdominal aortic aneurysm; EVAR, endovascular aneurysm repair.

Table 3 Mortality rates at discharge among patients undergoing surgical repair for AAA during the study period

	Included patients (N=16,737)
	Mortality
	Yes (n=601)		No (n=16,136)		OR	95% CI	P-value
	n	%	n	%
Age (years)
Mean (SD)	73.1 (6.64)		71.3 (7.80)		1.03	(1.02–1.04)	<0.001
Median (min–max)	74 (48–94)		72 (25–96)
Gender
Male	583	3.6	15,602	96.4	1	(0.69–1.79)	0.672
Female	18	3.3	534	96.7	1.11
Charlson Index
Mean (SD)	0.9 (1.14)		0.7 (0.97)		1.26	(1.17–1.34)	<0.001
Median (min–max)	1 (0–10)		0 (0–10)
Type of intervention
EVAR	85	1.2	6,724	98.8	1	(3.44–5.47)	<0.001
OSR	516	5.2	9,412	94.8	4.34
Intervention volume per hospital throughout the period/100
Mean (SD)	300.2 (149.59)		329.2 (159.51)		0.89	(0.84–0.94)	<0.001
Median (min–max)	276 (1–682)		314 (1–682)

Abbreviations: AAA, abdominal aortic aneurysm; EVAR, indicates endovascular aneurysm repair; OSR, open surgical repair.

Table 4 Multilevel logistic regression analysis of surgery selection and in-hospital mortality in public hospitals in Spain, 2002–2012

	Selection of EVAR			In-hospital mortality
	Model 1	Model 2	Model 3	Model 1	Model 2	Model 3
Specific individual average effects
Age (years)	1.90 (1.82–1.97)	1.93 (1.85–2.01)	1.89 (1.82–1.97)	1.58 (1.43–1.74)	1.58 (1.43–1.74)	1.58 (1.43–1.74)
Female vs male	1.02 (0.84–1.23)	0.94 (0.77–1.15)	1.02 (0.84–1.24)	0.89 (0.55–1.44)	0.90 (0.55–1.46)	0.89 (0.55–1.44)
Charlson Index	1.14 (1.10–1.18)	1.12 (1.08–1.16)	1.13 (1.10–1.18)	1.27 (1.19–1.37)	1.28 (1.20–1.37)	1.27 (1.19–1.37)
EVAR vs OSR	--------	--------	--------	0.17 (0.13–0.22)	0.18 (0.14–0.22)	0.17 (0.14–0.22)
Year		1.25 (1.23–1.26)			0.98 (0.95–1.01)
Specific contextual average effects
Volume of intervention			1.38 (1.14–1.67)			0.87 (0.79–0.97)
General contextual effects
ICC (%)	21.04	22.27	19.89	2.86	2.86	2.31
Median OR	2.44	2.56	2.37	1.35	1.35	1.30
AUC	0.51 (0.49–0.53)	0.48 (0.46–0.50)	0.51 (0.49–0.53)	0.74 (0.72–0.76)	0.74 (0.72–0.76)	0.74 (0.72–0.76)
Goodness of fit
DIC	19,649.96	18,361.55*	19,640.54	4,827.75	4,827.94	4,824.34*

Notes: Values are given as OR with 95% CI, unless stated otherwise. The intercept is not shown in the table.

* Significant change relative to model 1 (likelihood ratio: P<0.05).

Abbreviations: AUC, area under the receiver operating characteristic curve; DIC, Bayesian deviance information criterion; EVAR, endovascular aneurysm repair; ICC, intraclass correlation coefficient; OSR, open surgical repair.