Barsher NR, Menard MT, Nguyen LL et al. Infrainguinal bypass surgery is associated with lower perioperative mortality than major amputation in high risk surgical candidates. J Vasc Surg 2011:1251-59.

{users:STANDARD} In a nutshell

High-risk patients with significant systemic co-morbidities who present with critical ischaemia are frequently offered primary amputation rather than revascularisation because of the commonly held view that primary amputation carries lower risks, including lower mortality and therefore is a safer option. The aim of this study was to ascertain whether primary amputation is indeed associated with a survival benefit in a high-risk group.

This is a retrospective study based on the American College of Surgeons’ National Surgical Quality Improvement Project (NSQIP) database. Data on patients undergoing major amputation (below or above knee) and infrainguinal bypass surgery (prosthetic or autologous conduit) over a three-year period, (2005-2008) was collected. Out of this group a cohort of high-risk patients was identified. Two propensity matched groups with similar pre-operative characteristics and differing only in their treatment were created.

Of the patients, 792 underwent major amputation (366 above knee; 426 below knee) and 781 had infrainguinal bypass. Bypass patients had a lower 30-day mortality rate (6.54% vs. 9.97%; P=0.0147), lower rate of post-op sepsis (5.6% vs 14.1%), lower rate of pulmonary embolism ( 0% vs. 0.9%; p=0.009), and lower rate of post-op pneumonias and UTIs. On the other hand, bypass patients are more likely to be taken back to theatre for further intervention (27.6% vs. 14.1%; p<0.001), and were more likely to require post-operative transfusions. There was no difference in the time to discharge between the two groups.

Second opinion      

The credibility of this study lies in the large population sample it analyses, the number of pre-operative predictive factors it manages to identify, the clear exclusion criteria, and the propensity scoring to obtain two comparable groups.

This paper carefully analyses the pre-operative characteristics of patients undergoing infrainguinal bypass and amputations. It is therefore surprising that some factors widely accepted to predispose to post-operative complications, such as glycosylated haemoglobin, were not taken into consideration.

One of the limitations of this study is that this is not a randomised trial and confounding due to unmeasured variables may have an impact on outcomes. In particular, it is not clear whether the same proportion of patients in the two groups received high dependency or intensive unit care.

In this context it is extremely unlikely that a randomised controlled trial would ever be conducted and this study is the best evidence available showing that major amputation surgery is not a lower risk option than infrainguinal bypass surgery.

The verdict

• Infrainguinal bypass surgery carries lower mortality and morbidity than major amputation even in high-risk patients
• Severe systemic co-morbidities should not exclude the option of infrainguinal bypass surgery for limb salvage.

Jonathan Cutajar

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Kevin Cassar

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