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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2004;24:e147.)
© 2004 American Heart Association, Inc.

Letters to the Editor

Is There Really a Power Shortage in Clinical Trials Testing the "Homocysteine Hypothesis?"

G.J. Hankey; J.W. Eikelboom; K. Loh; Q. Yi; J. Pizzi; M. Tang; S. Hickling; M. Le; C.J. M. Klijn; P. Dusitanond; F. van Bockxmeer; A. Gelavis; R. Baker; K. Jamrozik

Stroke Unit (G.J.H., K.L., J.P., M.T., C.J.M.K., P.D.), Departments of Haematology (J.W.E., R.B.), Pathology (F.v.B.), and Pharmacy (A.G.), Royal Perth Hospital, Perth, Australia;, School of Medicine & Pharmacology (G.J.H., J.W.E., F.v.B., R.B.), School of Population Health (S.H., M.L., K.J.), University of Western Australia;, Biostatistics Department (Q.Y.), Princess Margaret Hospital, Toronto, Canada;, Imperial College (K.J.), London, United Kingdom

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

Results from a Substudy of the VITAmins TO Prevent Stroke (VITATOPS) Trial

Since January 1, 1998 the United States and Canada have implemented policies mandating the fortification of cereal grain flour products with folic acid (0.4 to 1.4 mg/lb) to reduce the risk of neural tube birth defects in newborns.¹ The disadvantage of this measure for researchers is that randomized, controlled trials of total homocysteine (tHcy)-lowering therapy, by means of folic acid and other multivitamin therapies, to prevent cardiovascular outcomes in the US and Canada are likely to achieve only 20% to 25% of the initially projected mean treatment effects of tHcy-lowering therapy (1.0 to 2.0 µmol/L versus 4.0 to 6.0 µmol/L).^2,3 Indeed, the recently completed Vitamins In Stroke Prevention (VISP) Study, which compared high-dose multivitamins (including folic acid 2.5 mg, vitamin B₁₂ 0.4 mg, and vitamin B₆ 25 mg) with low-dose multivitamins (including folic acid 0.02 mg, vitamin B₁₂ 0.006 mg, vitamin B₆ 0.2 mg) in 3,680 stroke survivors, only achieved a mean 2.0 µmol/L reduction in tHcy.^4,5 The results failed to reliably exclude a modest but clinically important effect of folic acid–based multivitamin therapy in reducing the risk of major vascular events and death by up to 20% and 30%, respectively.⁵

The VITAmins TO Prevent Stroke (VITATOPS) Trial is the only large randomized, double-blind, placebo-controlled trial currently testing the "homocysteine hypothesis" in patients with previous transient ischemic attack (TIA) or stroke.^6,7 It is being conducted in 19 countries, most where mandatory folic acid fortification of cereal grain products is not implemented. Patients are randomized to once daily . . . [Full Text of this Article]

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				G. Y.-H. Ho, J. W. Eikelboom, G. J. Hankey, C.-R. Wong, S.-L. Tan, J. B.-C. Chan, and C. P.L.-H. Chen Methylenetetrahydrofolate Reductase Polymorphisms and Homocysteine-Lowering Effect of Vitamin Therapy in Singaporean Stroke Patients Stroke, February 1, 2006; 37(2): 456 - 460. [Abstract] [Full Text] [PDF]