Table III. C-Statistics comparing the Risk Analysis Index (RAI)-only model discrimination versus the RAI-Procedure Complexity (RAI-PC) model including procedure characteristics for 30-day mortality, stratified by procedure category (e.g., AAA repair) and procedure type (endovascular versus open). The RAI-PC model adjusted for procedure category, procedure type, outpatient versus inpatient surgery status, general anesthesia use, work relative value units, and operative time.

Abbreviations: Peripheral Artery Disease (PAD), Abdominal Aortic Aneurysm (AAA), Thoracic Aortic Aneurysm (TAA), Thoracoabdominal Aortic Aneurysm (TAAA).

Procedure Category	Endovascular Surgery N = 32,492		Open Surgery N = 107,077
	C-statistic RAI [95% CI]	C-statistic RAI-PC [95% CI]	C-statistic RAI [95% CI]	C-statistic RAI-PC [95% CI]
All Procedures	0.719 [0.67–0.77]	0.805 [0.77–0.84]	0.723 [0.70–0.75]	0.795 [0.78–0.81]
AAA	0.722 [0.66–0.78]	0.840 [0.80–0.88]	0.713 [0.65–0.77]	0.765 [0.71–0.82]
Carotid	0.656 [0.39–0.92]	0.761 [0.47–1.00]	0.703 [0.65–0.75]	0.724 [0.68–0.77]
Infrainguinal	0.759 [0.67–0.85]	0.796 [0.71–0.88]	0.792 [0.76–0.82]	0.791 [0.76–0.82]
Suprainguinal	0.903 [0.82–0.99]	0.893 [0.79–1.00]	0.728 [0.68–0.78]	0.772 [0.73–0.82]
TAA	0.615 [0.46–0.77]	0.742 [0.63–0.86]	*	*
TAAA	0.685 [0.08–1.00]	0.982 [0.95–1.00]	0.565 [0.48–0.65]	0.740 [0.68–0.81]

^*There were too few observations in the open TAA procedure category to test model performance.