Open Repair of Ruptured Abdominal Aortic Aneurysms in a High-Volume Tertiary Referral Center: Proposal of a Prediction Model for 30-Day Mortality

Objective: About open surgical repair (OSR) in ruptured abdominal aortic aneurysms (rAAAs), several factors could affect the early outcomes. Some factors are modifiable, such as prompt diagnosis, time between symptoms and surgery, distance from the hospital, and surgical team's expertise. In Literature, a lot of studies identified predictive models to evaluate 30-day outcomes of rAAAs. All these models included preoperative clinical status and laboratory parameters. Aim of the study was to create a prediction model for 30-day mortality in patients underwent open surgical repair (OSR) for ruptured abdominal aortic aneurysm (rAAA) including pre- and intraoperative factors.

Methods: Between January 2007 and December 2020, 222 patients underwent OSR at our tertiary referral university hospital. Retrospective analysis of pre- and intraoperative factors was made by means of univariate analysis. Associations of patient and procedure variables with 30-day mortality rate were sought with multivariate Cox regression analysis. A mortality probability index was created by using a linear combination of all predictive factors multiplied by coefficients of the multiple logistic regression.

Results: Most of patients were male (189, 85.1%) with a mean age of 76.9 ± 8.7 years. Mean operation time was 221 ± 86 minutes. Overall, 30-day mortality rate was 28.8% (64 cases). Multivariate Cox regression analysis reported that age at intervention (>80 years), hypertension, congestive heart failure, chronic obstructive pulmonary disease, resuscitation maneuvers before surgery, loss of consciousness, and operation time >240 minutes were negative predictive factors for 30-day mortality risk (see [Table 1]). Patency of at least one hypogastric artery and infrarenal clamping had a protective role in reducing 30-day mortality rate. The analysis of the mortality index showed a cut-off point of 67.5 with a sensitivity of 81%, specificity of 78%, positive predictive value of 59%, and negative predictive value of 92%. Patients with values less than 67.5 had a 30-day mortality risk of 8.8%, while patient with values over 67.5 had a risk of 60.4%.

Conclusions: Elderly age, hypertension, congestive heart failure, chronic obstructive pulmonary disease, resuscitation maneuvers before surgery, loss of consciousness, and operation time >240 minutes affected 30-day mortality in patients undergoing OSR for rAAA. Patency of at least one hypogastric artery and infrarenal clamping had a protective role. In our mortality probability index a value over 67.5 increased the 30-day mortality risk up to 60%.

Table 1 Multivariate Cox regression analysis of perioperative factors affecting 30-day mortality rate

	Odds ratio	Standard error	p-Value	95% CI
Age >80 years	2.256525	.8467118	0.030	1.081547	4.707984
Hypertension	3.3555	1.746951	0.020	1.209489	9.309205
Coronary artery disease	5.460137	4.090968	0.023	1.257323	23.71156
COPD	2.162234	.8597463	0.049	.9918552	4.713646
Resuscitation maneuvers	5.853838	3.620603	0.004	1.741695	19.67476
Loss of consciousness	.3250352	.166321	0.028	.1192255	.8861179
Nasogastric tube	2.699938	1.701693	0.115	.7849933	9.286275
Operation time >240 minutes	2.551388	1.034004	0.021	1.152946	5.646041
Patency of at least one hypogastric artery	.0471537	.0549855	0.009	.0047967	.4635468
Suprarenal clamping	.2359236	.1280147	0.008	.0814517	.6833491
Infrarenal clamping	.211802	.1163848	0.005	.0721434	.6218188

Abbreviations: CI, Confident Interval; COPD, Chronic Obstructive Pulmonary Disease.

Reference

1. Tchana-Sato V, Sakalihasan N, Defraigne JO. [Ruptured abdominal aortic aneurysm]. Rev Med Liege 2018;73(5-6):296–299 PubMed