Omega-3 fatty acids for intermittent claudication

Abstract

BACKGROUND Omega-3 fatty acids are established as being effective in the treatment and prevention of coronary artery disease. It is possible that they may also benefit people with peripheral arterial disease, since the pathogenesis of the two conditions is similar. OBJECTIVES To determine the effects of omega-3 supplementation in people with intermittent claudication. SEARCH STRATEGY Trials were identified from the Cochrane Peripheral Vascular Diseases Group trials register (last searched April 2004), and the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched Issue 1, 2004). In addition, literature from pharmaceutical companies (Roche Pharmaceuticals and Seven Seas), manufacturers of omega-3 rich foods (Columbus Eggs) and web sites of nutritional organisations dedicated to omega-3 fatty acids (Omega-3 information and the Fish Foundation) were searched. SELECTION CRITERIA Randomised controlled trials of omega-3 fatty acids versus placebo or non-omega-3 fatty acids in people with intermittent claudication. DATA COLLECTION AND ANALYSIS One reviewer (TS) identified potential trials, assessed study quality and extracted data. The other reviewer (WH) assessed study quality and checked data extraction. MAIN RESULTS Four studies were included involving a total of 203 participants. The overall methodological quality of studies was good. All studies compared omega-3 fatty acid supplementation with placebo. Two studies used an omega-6 fatty acid as the placebo preparation, one used a monounsaturated fatty acid and one used a combination of omega-6 and monounsaturated fatty acids.Omega-3 fatty acid supplementation reduced triglyceride levels (weighted mean difference (WMD) -0.66 mmol/litre; 95% confidence interval (CI) -1.24 to -0.09) and diastolic blood pressure (WMD -1.94 mmHg; 95% CI -3.58 to -0.29) in the treatment group, but increased total cholesterol levels (WMD 0.41 mmol/litre; 95% CI 0.03 to 0.80) and LDL cholesterol levels (WMD 0.43 mmol/litre; 95% CI 0.12 to 0.74). Gastrointestinal side-effects were observed in one study. No significant changes were observed in pain-free walking distance (WMD -17 m; 95% CI -51 to 17 m), maximal walking distance (WMD -21 m; 95% CI -59 to 17 m) or ankle brachial pressure index (WMD -0.03; 95% CI -0.1 to 0.04). REVIEWERS' CONCLUSIONS Omega-3 fatty acids appear to have some beneficial biochemical and haemodynamic effects in people with intermittent claudication but there is no evidence of improved clinical outcomes. It should be noted that no consistent effect on primary outcome measures was detected. Further research is needed in this area, to evaluate short- and long-term effects on more clinically relevant outcomes.