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To the Editor: Dr Toole and colleagues¹ concluded that reduction of serum homocysteine levels had no effect on recurrent cerebral infarction, coronary heart disease, and death after 2 years of follow-up. As the authors acknowledged, the trial lacked statistical power to show the reduction in risk that would be expected from the observed changes in serum homocysteine levels. The average difference in serum homocysteine levels in the trial between the treated and control groups after 1 year was 2.2 µmol/L. It has been estimated² that a 3-µmol/L reduction in serum homocysteine level is associated with a relative risk of stroke of 0.76 (95% confidence interval [CI], 0.67-0.85) and a relative risk of coronary heart disease events of 0.84 (95% CI, 0.80-0.89). Therefore, a 2.2-µmol/L difference in serum homocysteine levels would, over enough time, be expected to result in an 18% (95% CI, 11%-25%) reduction in risk of stroke and a . . . [Full Text of this Article]

David S. Wald, MD, MRCP
d.s.wald@qmul.ac.uk
Wolfson Institute of Preventive Medicine
St Barts and The London School of Medicine and Dentistry
London, England

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