December 23, 2005

Factors Predictive of Infrainguinal Lower Extremity Arterial Bypass Graft Failure

Niten Singh, MD¹, Anton N. Sidawy, MD², Kent Dezee, MD², Richard F. Neville, MD³, Chris J. Abularrage, MD², Gilbert Aidinian, MD², Eric Adams, MD¹, Shukri Khuri, MD⁴, William Henderson, PhD.⁵.
¹Georgetown Univ/Washington Hosp.Center, Washington, DC, USA, ²VAMC, Washington, DC, USA, ³Georgetown University, Washington, DC, USA, ⁴VAMC, West Roxbury, MA, USA, ⁵NSQIP data center, Denver, CO, USA.
Objectives:
Various factors have been associated with acute failure of lower extremity arterial bypass grafts. We analyzed a large clinical database to investigate which factors were associated with a higher incidence of graft failure in infrainguinal bypass.
Methods:
This study analyzes prospectively collected data from the National Surgical Quality Improvement Program (NSQIP) of the Veterans Affairs Medical Centers. All patients from 1995-2003 in the NSQIP database who underwent infrainguinal arterial bypass were identified by CPT codes. Thirty-day graft failure data were evaluated utilizing univariate analysis as well multivariate logistic regression to control for possible confounders.
Results:
The NSQIP database identified 14,788 patients who underwent an infrainguinal lower extremity arterial bypass during the study period. Patients in the age group less than 50 had a significantly higher rate of graft failure versus those in the 51-60 year, 61-70 year, and greater than 71 year age groups on univariate and multivariate analysis (Table 1). Diabetics, whether they are on oral medication or insulin, were less likely to have acute graft failure than non-diabetics. African-Americans had higher odds of graft failure versus all other races. In addition, patients with a higher hematocrit had a less chance of graft failure (Table 2). Smoking was not a significant factor for acute graft failure on univariate as well as multivariate analysis. Multivariate analysis of the type of procedure revealed femoral artery to popliteal artery bypass with vein was not associated with statistically significant lower odds of graft failure than with prosthetic. However, in comparison to this type of bypass the following infrainguinal bypass configurations were associated with higher odds of failure: femoral artery to tibial artery bypass with vein, in-situ femoral artery to tibial artery bypass, in-situ popliteal artery to tibial artery bypass, and femoral artery to tibial vessel with prosthetic (Table 3).
Conclusion:
These data suggest that many factors have an impact on the 30-day graft failure rates of infrainguinal bypasses. These results help the vascular surgeon to predict more accurately early bypass failure rates while planning the procedure and counseling patients about its prognosis.

Table 1 Univariate analysis of age and graft failure


	Univariate analysis of age and graft failure			Multivariate logistic regression analysis of age and graft failure (Age 70 and older as reference)
Age	Total # of Bypasses	# of Failures	Percent Failure	OR	95%CI	P-value
Less than 50	1035	85	8.21*	2.14	1.56-2.94	P<0.0001
51-60	3248	171	5.26*	1.38	1.18-1.61	P<0.0001
61-70	5354	242	4.52	1.12	0.95-1.31	P<0.168
Greater than 70	5151	225	4.37	Ref	Ref	Ref

*=P<0.0001 Chi Square
Table 2


Factor	OR	95% CI	P-value*
Diabetics on oral medication	0.71	0.57-0.88	0.002
Diabetics on insulin	0.73	0.58-0.91	0.005
Higher hematocrit	0.98	0.98-0.99	0.001
African Americans	1.39	1.25-1.55	0.001

*=by multivariate logistic regression
Table 3


Procedure	OR	95% CI	P-value*
Femoral to popliteal with vein	Ref
Femoral to popliteal with prosthetic	0.91	0.74-1.11	0.34
Femoral to tibial with vein	1.73	1.52-1.97	0.0001
In-situ femoral to tibial	1.95	1.69-2.24	0.0001
In-situ popliteal to tibial	1.69	1.24-2.32	0.001
Femoral to tibial with prosthetic	2.20	1.74-2.77	0.0001

*=by multivariate logistic regression

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