Omega-3 fatty acids for intermittent claudication.

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 clinical and haematological 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 August 2007), and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (last searched Issue 3, 2007). In addition, we searched literature from pharmaceutical companies, manufacturers of omega-3 rich foods and web sites of nutritional organisations dedicated to omega-3 fatty acids.

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 author identified potential trials. Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information if necessary.

MAIN RESULTS

Six studies were included representing 313 participants. All studies compared omega-3 fatty acid supplementation with placebo lasting from 4 weeks to 2 years. Two studies with long treatment periods administered additional substances, making any observed effects impossible to attribute to omega-3 fatty acids and were therefore excluded from the statistical analyses. No significant differences between intervention and control groups were observed in ankle brachial pressure index (ABPI) (weighted mean difference (WMD) -0.02; 95% CI -0.09 to 0.05), systolic blood pressure (WMD 5.00 mmHg; 95% CI -11.59 to 21.59), plasma viscosity (WMD 0.03 mPa/s; 95% CI -0.02 to 0.08), pain-free walking distance (PFWD) (WMD 7.46 m; 95% CI -25.47 to 40.39), or maximal walking distance (MWD) (WMD 0.27 m; 95% CI -39.59 to 40.13). Blood viscosity levels decreased. Gastrointestinal side effects were observed in two studies. Omega-3 fatty acid supplementation increased (low-density lipoprotein) LDL cholesterol levels (WMD 0.80 mmol/litre; 95% CI 0.34 to 1.26) and total cholesterol levels (WMD 0.64 mmol/litre; 95% CI 0.08 to 1.20).

AUTHORS' CONCLUSIONS: Omega-3 fatty acids appear to have limited haematological benefits in people with intermittent claudication but there is no evidence of consistent improved clinical outcomes which are the primary outcomes of this review (quality of life, PFWD, MWD, ABPI, angiographic findings). Supplementation may also cause adverse effects such as increased total and LDL cholesterol levels. Further research is needed in this area, to evaluate short- and long-term effects on more clinically relevant outcomes.