Postoperative and amputation-free survival outcomes after femorodistal bypass grafting surgery: findings from the Department of Veterans Affairs National Surgical Quality Improvement Program.

PURPOSE

A noncardiac surgery risk model was used as a means of analyzing variations in postoperative mortality and amputation-free survival for older veterans undergoing femorodistal bypass grafting surgery.

METHODS

A prospective cohort study was undertaken in 105 Veterans Affairs (VA) hospitals at the time of index operation from 1991 to 1995. Each patient was linked to subsequent hospitalizations, major amputation surgery, and survival through 1999. Logistic regression and proportional hazards models were used as a means of developing risk indices on the basis of risk factors from the VA National Surgical Quality Improvement Program. A total of 4288 male veterans 40 years or older underwent artificial, vein, or in situ bypass grafting surgery at the femoral to tibial level. The main outcome measures were 30-day postoperative mortality and amputation-free survival.

RESULTS

Approximately half of all patients had undergone an earlier revascularization or amputation at any level for vascular disease. The 30-day postoperative mortality rate was 2.1% and varied greatly between mortality risk index quartiles (0.6%-5.2%). In a median 44.3 months of follow-up, surviving patients had 17,694 subsequent VA hospitalizations, 1147 patients (26.7%) underwent subsequent major amputation, and 1913 patients (44.6%) died. The overall survival probability was 88% at 1 year and 63% at 5 years; 1- and 5-year (any sided) limb salvage rates were 87% and 74%, respectively, for patients who underwent a femoropopliteal bypass grafting procedure, compared with 77% and 63%, respectively, for patients who underwent a tibial bypass grafting procedure. When amputation and death were combined as end points, amputation-free survival probability rates at 1, 3, and 7.5 years were 74%, 56%, and 29%, respectively. Patients with the best 20% survival risk scores had observed mean survival probability rates 30% higher than patients in the poorest 20% of survival risk.

CONCLUSION

Risk indices derived from the preoperative workup may be of use to clinicians in assessing and communicating risk and prognosis. Risk-adjustment of outcomes is critical for evaluating future disease management initiatives for patients with advanced peripheral arterial disease.