Risk score for one-year mortality following emergent infra-inguinal bypass

The purpose of this study is to identify variables that place patients at higher risk for mortality following emergent infra-inguinal bypass. Further, this study will create a risk score for mortality following emergent infra-inguinal bypass to help tailor postoperative and long-term patient management.

In the Vascular Quality Initiative, we identified 2126 patients who underwent emergent infra-inguinal artery bypass. Two primary outcomes were investigated: 30 day mortality following emergent infra-inguinal bypass; and 1-year mortality following emergent infra-inguinal bypass. The first step in analysis was univariable analysis for each outcome with χ² analysis for categorical variables and Student t-test for comparison of means of ordinal variables. Next, binary logistic regression analysis was performed for each outcome utilizing variables that achieved a univariable P value ≤ .10. Factors with a multivariable P value ≤ .05 were included in the risk score, and points were weighted and assigned based on the respective regression beta-coefficient in the multivariable regression.

Variables with a significant multivariable association (P < .05) with 1-year mortality were: increasing age; body mass index less than 20 kg/m²; coronary artery disease; active hemodialysis at time of presentation; anemia at admission; prosthetic conduit for emergent bypass; postoperative myocardial infarction; postoperative acute renal insufficiency; perioperative stroke; baseline non-ambulatory status; new onset hemodialysis requirement perioperatively; need for bypass revision or thrombectomy during index admission; lack of statin prescription at discharge; lack of antiplatelet medication at discharge; and, lack of anticoagulation at time of hospital discharge. Pertinent negatives included all sociodemographic variables including rural living status, insurance status, and Area Deprivation Index home area. The risk score achieved an area under the curve of 0.820, and regression analysis of the risk score achieved an overall accuracy of 87.9% with 97.7% accuracy in predicting survival, indicating the model performs better in determining which patients will survive rather than precisely determining who will experience 1-year mortality.

Discharge medications are the primary modifiable variable impacting survival after emergent infra-inguinal bypass surgery. In the absence of contraindication, all these patients should be discharged on antiplatelet, statin, and anticoagulant medications after emergent infra-inguinal bypass as they significantly enhance survival. Social determinants of health do not impact survival among patients treated with emergent infra-inguinal bypass at Vascular Quality Initiative centers. A risk score for mortality at 1 year after emergent infra-inguinal bypass has been created that has excellent accuracy.