Volume-outcome relationships in lower extremity arterial bypass surgery

We sought to investigate whether a volume-outcome relationship exists for lower extremity arterial bypass (LEAB) surgery.

All LEAB procedures performed in England between 2002 and 2006 were identified from Hospital Episode Statistics data. A Charlson-type risk profile, including operating hospital annual case volume, was identified per patient. Outcome measures of revision bypass, amputation, death and a composite measure were established during the index admission and at 1 year.Quintile analysis and multilevel multivariate modeling were used to identify the existence of a volume-outcome relationship and allow adjustment of results for significant determinants of outcome.

A total of 27,660 femoropopliteal bypass and 4161 femorodistal bypass procedures were identified.As volume increased, in-hospital mortality after popliteal bypass decreased from 6.5% to 4.9% (P = 0.0045), with a corresponding odds ratio of 0.980 [95% confidence interval (CI), 0.929-0.992; P = 0.014] for every increase of 50 patients per year. Major amputation decreased from 4.1% to 3.2% (P = 0.006) in high-volume hospitals, with a reduction in risk of 0.955 (95% CI, 0.928-0.983; P = 0.002) at 1 year.For distal bypass, in-hospital mortality decreased from 9.8% to 5.5% (P = 0.004) and 1-year major amputation decreased from 25.4% to 18.2% (P < 0.001), with a corresponding odds ratio of 0.658 (95% CI, 0.517-0.838; P < 0.0001) as the volume increased.An increase in the chance of revision surgery (10.6% vs 8.2%, P < 0.001) was seen with higher volume, with an increased odds ratio of 1.031 (95% CI, 1.005-1.057; P = 0.018).

A positive volume-outcome relationship exists for LEAB procedures even after employing multilevel risk adjustment models. There are benefits in terms of mortality and limb salvage both in the short-term and at 1 year postsurgery.