The effectiveness of aspirin may be hindered by high cholesterol levels, according to new research. Researchers from the University of Maryland, Baltimore, United States, examined the effectiveness of aspirin in a study of 63 patients who had heart disease and had been taking 325mg aspirin daily for at least 30 days. Of the patients who had a cholesterol level above 5.7mmol/L, 60 per cent had platelet aggregation despite taking aspirin, compared with 20 per cent of patients with cholesterol levels below 4.7mmol/L. The researchers say that other strategies are needed for patients with high cholesterol who are not responding to aspirin. They suggest using a higher dose of aspirin or making more aggressive efforts to reduce total cholesterol levels. The results were presented at the American Heart Association's annual meeting in New Orleans, US, on November 14.