Lipid-lowering for peripheral arterial disease of the lower limb.

BACKGROUND Lipid-lowering therapy is recommended for secondary prevention in people with coronary artery disease. It may also reduce cardiovascular events and/or local disease progression in people with lower limb peripheral arterial disease (PAD). OBJECTIVES To assess the effects of lipid-lowering therapy on all-cause mortality, cardiovascular events and local disease progression in patients with PAD of the lower limb. SEARCH STRATEGY The authors searched The Cochrane Peripheral Vascular Diseases Group's Specialised Register (last searched February 2007) and the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched Issue 2, 2007) for publications describing randomised controlled trials of lipid-lowering therapy in peripheral arterial disease of the lower limb. SELECTION CRITERIA Randomised controlled trials of lipid-lowering therapy in patients with PAD of the lower limb. DATA COLLECTION AND ANALYSIS Three authors independently assessed trial quality and extracted data. MAIN RESULTS Eighteen trials were included, involving a total of 10,049 participants. Trials differed considerably in their inclusion criteria, outcomes measured, and type of lipid-lowering therapy used. Only one trial (PQRST) reported a detrimental effect of active treatment on blood lipid/lipoprotein levels. The pooled results from all eligible trials indicated that lipid-lowering therapy had no statistically significant effect on overall mortality (Odds Ratio (OR) 0.86; 95% Confidence Interval (CI) 0.49 to 1.50) or on total cardiovascular events (OR 0.8; 95% CI 0.59 to 1.09). However, subgroup analysis which excluded PQRST showed that lipid-lowering therapy significantly reduced the risk of total cardiovascular events (OR 0.74; CI 0.55 to 0.98). This was primarily due to a positive effect on total coronary events (OR 0.76; 95% CI 0.67 to 0.87). Greatest evidence of effectiveness came from the use of simvastatin in people with a blood cholesterol >/= 3.5 mmol/litre (HPS). Pooling of the results from several small trials on a range of different lipid-lowering agents indicated an improvement in total walking distance (Weighted Mean Difference (WMD) 152 m; 95% CI 32.11 to 271.88) and pain-free walking distance (WMD 89.76 m; 95% CI 30.05 to 149.47) but no significant impact on ankle brachial index (WMD 0.04; 95% CI -0.01 to 0.09). AUTHORS' CONCLUSIONS Lipid-lowering therapy is effective in reducing cardiovascular mortality and morbidity in people with PAD. It may also improve local symptoms. Until further evidence on the relative effectiveness of different lipid-lowering agents is available, use of a statin in people with PAD and a blood cholesterol level >/=3.5 mmol/litre is most indicated.