Bypass surgery for chronic lower limb ischaemia.

BACKGROUND

Surgical bypass of an occluded arterial segment is the mainstay of treatment for patients with critical limb ischaemia. As with many surgical interventions, however, it was introduced without formal evaluation.

OBJECTIVES

The objective of this review was to determine the effects of bypass surgery in patients with chronic lower limb ischaemia.

SEARCH STRATEGY

The reviewers searched the Cochrane Peripheral Vascular Diseases Group trials register, MEDLINE, EMBASE, reference lists of relevant articles, and contacted principal trial investigators.

SELECTION CRITERIA

All randomised controlled trials of bypass surgery versus control, or versus any other form of treatment.

DATA COLLECTION AND ANALYSIS

At least two reviewers extracted data and assessed trial quality independently. The reviewers contacted investigators to obtain information or data needed for the review that could not be found in published reports. Dichotomous data were analysed using the Peto odds ratio (OR), and continuous data with the weighted mean difference (fixed effect and random effects models).

MAIN RESULTS

Eight trials were identified which appeared to meet the inclusion criteria, but two were subsequently excluded. The remaining six trials involved a total of just over 700 patients, two trials comparing bypass surgery with angioplasty (PTA), and one with each of thromboendarterectomy, thrombolysis, exercise, and spinal cord stimulation. Four trials included patients with a range of disease severity (intermittent claudication and critical limb ischaemia), one was restricted to claudicants only and another to only critical limb ischaemia. The type of bypass procedure performed in each trial was similar: vein grafts for distal reconstructions; synthetic prostheses for aorto-iliac or ilio-femoral bypasses. The outcome measures varied, but four of the six trials included mortality and operative failure. In general the quality of the trials was good, but none was blinded because of the nature of the intervention. There were no clear differences between bypass surgery and PTA. Mortality and amputation rates did not differ significantly, although primary patency was significantly higher in the bypass group after 12 months (Peto OR 1. 6, 95% CI 1.0, 2.6) but not after four years (p=0.14). Compared with thrombolysis, amputation rates were significantly lower in the bypass group (Peto OR 0.2, 95% CI 0.1, 0.6), but mortality rates did not differ. Compared with thromboendarterectomy, restoration of blood flow was significantly greater in the bypass patients (Peto OR 9.2, 95% CI 1.7, 50.6), but mortality and amputation rates did not differ. Bypass did not differ significantly from exercise or spinal cord stimulation.

REVIEWER'S CONCLUSIONS: There is limited evidence for the effectiveness of bypass surgery and further large trials are required.