December 12, 2008

Factors Associated With Survival Following Lower Extremity Bypass In Northern New England

Philip P. Goodney, MD, Brian C. Nolan, MD, Andrew C. Stanley, MD, Daniel J. Bertges, MD, Jens Eldrup-Jorgensen, MD, Donald S. Likosky, PhD, Jack L. Cronenwett, MD.
Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.

Objectives: Surgeons must weigh the morbidity incurred during lower extremity bypass (LEB) with the likelihood of survival following surgery. Therefore, we developed a model to predict survival one year following LEB.
Methods: We studied a prospective registry of 2,515 patients who underwent LEB between 2003-2007 across 11 hospitals and 50 surgeons. Cox proportional hazards models were used to determine predictors of survival within the first year following LEB.
Results: Average patient age was 68, the majority (66%) of patients were male, and many had significant comorbidities (86% were hypertensive, 65% diabetic, and 41% had coronary disease). In most patients, the indication for surgery was critical limb ischemia (73%). Overall survival by life table analysis was 98% at the time of discharge, and 90% at 1 year (Figure). Multivariate Cox models demonstrated that an emergent operation, post operative myocardial infarction, renal failure, increased age, tissue loss, and need for statin therapy all were associated with increased risk of death at 1 year. The use of beta blockers, the presence of single segment vein conduit, and discharge to home all were associated with decreased risk of death at 1 year (Table). Using this model for risk adjustment, most hospitals in our region performed as expected. However, two hospitals had fewer deaths than expected, while two hospitals had more deaths than expected.
Conclusions: Using these variables, surgeons can risk-stratify patients and inform them more precisely about their likelihood of survival following LEB, as well as compare risk-adjusted outcomes across centers and facilitate quality improvement efforts.

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