Risk Score Model for Major Amputation Following Peripheral Vascular Intervention
ALBEIR MOUSA, MD.,FACS.,RPVI.,MPH.,MBA1, Michael Yacoub, MD.,FACS.,RPVI1, Mike Broce, BA2, Ali AbuRahma, MD.,FACS.,RVI1.
1West Virginia Univeristy, Charleston, WV, USA, 2CAMC Research Institiute, Charleston, WV, USA.
Objective(s): The purpose of this study was to identify significant predictors of major amputation following peripheral vascular intervention (PVI) and use those results to create a risk score model.
Methods: We included all PVI cases of a national data-set from the Society for Vascular Surgery Patient Safety Organization Quality Improvement (SVS-VQI). Patients with available data points and single-side-single-artery intervention were included, while those with previous amputations were excluded. Index target artery location was classified as (1) above inguinal, (2) inguinal to popliteal or (3) below popliteal. Clinical and anatomic variables were analyzed with Kaplan-Meier and Cox-regression models to determine predictors of amputation. Based on the beta coefficients of the regression model, a risk-score point system was created, and then used to categorize patients into low, moderate and high risk for amputation.
Results: A total of 16,262 PVI cases with available data were included. Average age was 67.2 ± 11.1 years, a slight majority were male (59.4%) with a history of hypertension (86.9%), diabetes (46.0%) and smoking (39.3%). There were 680 (4.2%) major amputations during the follow-up period. Several factors were associated with amputation: below popliteal index artery location (Hazard Ratio [HR], 1.8; P <0.001), treated with stent (HR, 0.8; P<0.041), TASC score [(B): HR, 1.3; P=0.037; (C): HR, 1.6; P<0.001; (D) HR, 1.7; P<0.001 )], ASA classification [(severe): HR, 1.4; P=0.004; (life threatening) HR, 2.5; P<0.001)], indication [(claudication/rest pain) HR, 0.5; P<0.01, (tissue loss/ischemia) HR, 2.2; P<0.001)]. Age by decade, history of diabetes, congestive heart failure, BMI>30, and discharged home on anticoagulant or antiplatelet were also significant predictors of amputation. With our scoring model, 3 year survival from amputation rates for patients with low, moderate, and high risk were 98.1+ 0.3(SE), 85.0 +2.9 (SE) and 70.2 +2.7 (SE); p<0.001, see figure 1. Conclusion: Three-year survival from amputation following PVI in patients with a high-risk score utilizing the model provided was 70.2%. Patients with unfavorable pre-intervention conditions and co-morbidities can be identified with our model which may be more applicable in high volume contemporary institutions.
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