Early Graft Failure After Lower Extremity Arterial Bypass: Results from More Than 200 Hospitals

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ASSOCIATION FOR ACADEMIC SURGERY AND SOCIETY OF UNIVERSITY SURGEONS—ABSTRACTS

(FG) for collagen III, photographed under polarized light, and analyzed to determine the SR:FG ratio. Results: Mean subject age at T2, M:F ratio, mean duration of scaffold indwelling, and ratio of onlay:inlay:sublay location were 55.9 years, 7:8, 681.3 days, 3:1:11, respectively. SR/FG significantly correlated with ACS wound class at T1 (p¼0.01), CCI at T1 (p¼0.02), and CCI at T2 (p¼0.02). Cell infiltration significantly correlated with subject age at T2 (p¼0.00), CCI at T1 (p¼0.00), and CCI at T2 (p¼0.00). Fibrous encapsulation significantly correlated with scaffold location (p¼0.03). Neovascularization significantly correlated with subject age at T2 (p¼0.00). When duration of scaffold indwelling was categorized as 0, 1-6, 7-12, 13-18, 19-24, and >24 months, greater indwelling durations significantly correlated with greater composite remodeling score (p¼0.00), cell infiltration (p¼0.00), cell type (p¼0.01), extracellular matrix deposition (p¼0.03), and neovascularization (p¼0.02). Conclusions: As hypothesized, greater ratios of collagen I:III significantly correlated with greater ACS wound class at T1, and greater CCI at both T1 and T2. Mean composite scores for remodeling did not significantly correlate with subject characteristics or wound class. However, significant correlations were found between greater cell infiltration and greater CCI at both T1 and T2; and greater fibrous encapsulation and inlay location. With greater indwelling duration, scaffolds demonstrated significantly greater overall remodeling, cell infiltration, favorable cell types, ECM deposition, and neovascularization, but not scaffold degradation or fibrous encapusulation. Host characteristics and surgical site assessments may predict degree of remodeling following abdominal wall repair for costly biologic scaffolds.

35.6. Early Graft Failure After Lower Extremity Arterial Bypass: Results from More Than 200 Hospitals. G. Soma, D. Y. Greenblatt, M. T. Nelson, J. Havlena, C. C. Greenberg, K. C. Kent; University of Wisconsin School of Medicine and Public Health, Department of Surgery, Madison, WI Introduction: Early graft failure (EGF) is a serious complication after lower extremity arterial bypass. EGF has not been examined using national data since the widespread adoption of percutaneous treatments for LE arterial occlusive disease. To address this gap, we utilized data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP), which includes more than 200 academic and community hospitals. Methods: Patients who underwent lower extremity arterial bypass from 2005 to 2009 were selected from the ACS NSQIP database. The frequency of 30-day EGF NSQIP variable ‘‘OTHGRAFL’’ was determined. Univariate and multivariate methods were utilized to identify risk factors for EGF. Results: Of 13,751 patients who underwent open lower extremity arterial bypass, 733 (5.6%) had EGF. Patients who suffered EGF had a longer mean length of hospital stay (11.4 vs. 6.4 d, p<0.001), and had higher rates of reoperation (83.3% vs. 14.8%, p<0.001) and 30-day mortality (5.6% vs. 2.2%, p<0.001). The rate of other complications in patients who suffered EGF was 37.2%, compared to 19.1% in those who did not have EGF (p<0.001). In patients who had both EGF and another complication, the majority (77.3%) experienced the other complication subsequent to EGF. In a multivariable model, factors associated with EGF included younger age, female gender, smoking, prior operation, femoral to tibial bypass, prosthetic graft, and emergent operation (Table). Conclusions: In an era of increased utilization of percutaneous techniques, EGF after open lower extremity arterial bypass remains a common event, with serious consequences. EGF is strongly associated with developing other complications, reoperation, and mortality. We have identified a number of risk factors for EGF, which may be of use for pre-operative counseling and decision making.

TABLE Significant Risk Factors for Early Graft Failure After Lower Extremity Arterial Bypass. Odds Ratios (ORs) and Confidence Intervals (CIs) are Adjusted for 17 Variables Including Demographics, Comorbid Conditions, Preoperative Lab Values, and Operative Factors Risk Factor

Adjusted OR (95% CI)

Age < 50 (vs. 60-69) Female Smoker Prior operation within 30 d Emergent operation Bypass type Femoral to popliteal Femoral to tibial Popliteal to tibial Graft type Reversed vein Prosthetic

1.48 (1.13 – 1.96) 1.24 (1.06 – 1.44) 1.23 (1.04 – 1.46) 1.34 (1.04 – 1.73) 1.68 (1.29 – 2.19) Referent 2.10 (1.78 – 2.49) 1.79 (1.38 – 2.32) Referent 1.25 (1.05 – 1.50)

35.7. Diagnosis of Venous Thromboembolism as an Outpatient in Patients Undergoing Surgical Treatment for Malignancy: An Analysis of ACS NSQIP Data 2005-2008. C. E. Reinke, G. C. Karakousis, R. A. Hadler, J. A. Drebin, D. L. Fraker, R. R. Kelz; Department of Surgery, Philadelphia, PA Introduction: the relationship between malignancy, surgery and venous thromboembolism (VTE) is well established. Previous studies have reported that the incidence of VTE varies by tumor type. Current guidelines provide recommendations on use of inpatient pharmacoprophylaxis for surgical oncology patients. the practice of continuing pharmacoprophylaxis after discharge is reserved for the ‘‘high-risk’’ patient and the use of this practice varies widely. Little is known regarding rates of outpatient VTE diagnosis by tumor site for surgical patients. the current study was designed to determine the likelihood of VTE diagnosis after hospital discharge by site of neoplasm to help inform surgeons when deciding upon the duration of pharmacoprophylaxis for their cancer patients. Methods: We performed a retrospective cohort study of patients entered into the ACS-NSQIP database from 2005-2008 who underwent a surgical procedure and had a post-operative neoplasm diagnosis. The incidence of VTE was calculated by tumor site for malignant neoplasms and the median post-operative day of diagnosis of VTE and median post-operative day of discharge were calculated and compared across cancer types. We report 30-day VTE outcomes and censored length of stay at 30 days. Patients with neoplams in the field of general surgery, gynecologic and genitourinary surgery were analyzed. Patients with VTE diagnosis on the day of discharge were excluded from the analysis of outpatient status (n¼13) as well as patients who were missing day of diagnosis of VTE (n¼6). For VTE patients, diagnosis status (inpatient versus outpatient) was determined and the percent of VTE patients diagnosed as an outpatient was compared across groups. An incidence of post-discharge VTE diagnosis was determined by multiplying the incidence and the percent of patients with outpatient discharge for each malignancy site. Results: Out of 130,284 patients who underwent surgery for neoplasm, there were 92,072 with malignant diagnosis by pathology, of which 76,479 were included in the analysis. The incidence of VTE varied substantially by site of malignancy (0-51 events per 1000 cases). Percent of VTE events diagnosed as an outpatient varied as well, ranging from 0 to 100% (see Table). The absolute incidence of VTE diagnosed as an outpatient ranged from 0 to 10.1 per 1000 cases, with malignancies of the pancreas, stomach and prostate having