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Publications (7)20.99 Total impact

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    ABSTRACT: Epidemiological studies suggest that raised plasma concentrations of total homocysteine (tHcy) may be a common, causal and treatable risk factor for atherothromboembolic ischaemic stroke, dementia and depression. Although tHcy can be lowered effectively with small doses of folic acid, vitamin B(12) and vitamin B(6), it is not known whether lowering tHcy, by means of B vitamin therapy, can prevent stroke and other major atherothromboembolic vascular events. To determine whether the addition of B-vitamin supplements (folic acid 2 mg, B(6) 25 mg, B(12) 500 microg) to best medical and surgical management will reduce the combined incidence of stroke, myocardial infarction (MI) and vascular death in patients with recent stroke or transient ischaemic attack (TIA) of the brain or eye. A prospective, international, multicentre, randomised, double blind, placebo-controlled clinical trial. One hundred and four medical centres in 20 countries on five continents. Eight thousand (6600 recruited as of 5 January, 2006) patients with recent (<7 months) stroke (ischaemic or haemorrhagic) or TIA (brain or eye). RANDOMISATION: Randomisation and data collection are performed by means of a central telephone service or secure internet site. One tablet daily of either placebo or B vitamins (folic acid 2 mg, B(6) 25 mg, B(12) 500 mug). The composite of stroke, MI or death from any vascular cause, whichever occurs first. Outcome and serious adverse events are adjudicated blinded to treatment allocation. TIA, unstable angina, revascularisation procedures, dementia, depression. STATISTICAL POWER: With 8000 patients followed up for a median of 2 years and an annual incidence of the primary outcome of 8% among patients assigned placebo, the study will have at least 80% power to detect a relative reduction of 15% in the incidence of the primary outcome among patients assigned B vitamins (to 6.8%/year), applying a two-tailed level of significance of 5%. VITATOPS aims to recruit and follow-up 8000 patients between 1998 and 2008, and provide a reliable estimate of the safety and effectiveness of folic acid, vitamin B(12), and vitamin B(6) supplementation in reducing recurrent serious vascular events among a wide range of patients with TIA and stroke throughout the world.
    International Journal of Stroke 05/2007; 2(2):144-50. · 2.75 Impact Factor
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    ABSTRACT: BACKGROUND: Epidemiological studies suggest that raised plasma concentrations of total homocysteine (tHcy) may be a common, causal and treatable risk factor for atherothromboembolic ischaemic stroke, dementia and depression. Although tHcy can be lowered effectively with small doses of folic acid, vitamin B(12) and vitamin B(6), it is not known whether lowering tHcy, by means of B vitamin therapy, can prevent stroke and other major atherothromboembolic vascular events. AIM: To determine whether the addition of B-vitamin supplements (folic acid 2 mg, B(6) 25 mg, B(12) 500 microg) to best medical and surgical management will reduce the combined incidence of stroke, myocardial infarction (MI) and vascular death in patients with recent stroke or transient ischaemic attack (TIA) of the brain or eye. DESIGN: A prospective, international, multicentre, randomised, double blind, placebo-controlled clinical trial. SETTING: One hundred and four medical centres in 20 countries on five continents. SUBJECTS: Eight thousand (6600 recruited as of 5 January, 2006) patients with recent (<7 months) stroke (ischaemic or haemorrhagic) or TIA (brain or eye). RANDOMISATION: Randomisation and data collection are performed by means of a central telephone service or secure internet site. INTERVENTION: One tablet daily of either placebo or B vitamins (folic acid 2 mg, B(6) 25 mg, B(12) 500 mug). PRIMARY OUTCOME: The composite of stroke, MI or death from any vascular cause, whichever occurs first. Outcome and serious adverse events are adjudicated blinded to treatment allocation. SECONDARY OUTCOMES: TIA, unstable angina, revascularisation procedures, dementia, depression. STATISTICAL POWER: With 8000 patients followed up for a median of 2 years and an annual incidence of the primary outcome of 8% among patients assigned placebo, the study will have at least 80% power to detect a relative reduction of 15% in the incidence of the primary outcome among patients assigned B vitamins (to 6.8%/year), applying a two-tailed level of significance of 5%.
    International Journal of Stroke 02/2007; 2(2):144-150. · 2.75 Impact Factor
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    ABSTRACT: It is uncertain what impact increasing voluntary folate fortification may be having on the statistical power of randomized trials testing the homocysteine hypothesis of atherothrombosis. The objective of this study was to determine whether there has been a change in folate status between 1998 and 2002 in stroke patients randomized into the VITAmins TO Prevent Stroke (VITATOPS) Study at a single center in Perth, Australia, and what impact this may have had on the magnitude of the homocysteine-lowering effect achieved over time with folic acid-based multivitamin therapy. We conducted a randomized, double-blind, placebo-controlled study involving 285 patients with stroke or transient ischemic attack who were recruited between 1998 and 2002 and randomized to long-term folic acid 2.0 mg/day, pyridoxine 25 mg/day and cobalamin 0.5 mg/day (active VITATOPS medication) or placebo. Fasting plasma total homocysteine, red cell folate, serum cobalamin and serum pyridoxine levels were measured at baseline and 6 months, and the change in blood levels over 4 time quartiles and differences in levels between the two randomized treatments were examined. Between 1998 and 2002, there was a significant rise in baseline mean red cell folate levels over 4 time quartiles among the entire stroke cohort (723.3, 780.1, 922.6 and 1,023.7 nmol/l in the first, second, third and fourth quartiles, respectively; p < 0.0001), but this was not associated with a spontaneous reduction in mean baseline total homocysteine levels during the same time period (12.7, 14.3, 12.1 and 12.8 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.55). The homocysteine-lowering effect of the active VITATOPS trial medication at 6 months after randomization also did not change significantly between 1998 and 2002 (difference between randomized groups: -4.1, -4.1, -3.1 and -3.6 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.56). The homocysteine-lowering effect of the active VITATOPS trial medication has not attenuated significantly in the past 5 years despite increasing voluntary fortification of foods with folic acid as reflected by a progressive rise in baseline folate status. These data suggest that in the continuing absence of a program of mandatory folate fortification of food in populations served by centers participating in the VITATOPS trial, the study will remain adequately powered to test the homocysteine-lowering hypothesis for which it was designed.
    Cerebrovascular Diseases 02/2005; 19(2):110-6. · 2.81 Impact Factor
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    ABSTRACT: 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.
    Arteriosclerosis Thrombosis and Vascular Biology 08/2004; 24(8):e147-8. · 6.34 Impact Factor
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    ABSTRACT: 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.
    Arteriosclerosis Thrombosis and Vascular Biology 08/2004; 24(8):e147-8. · 6.34 Impact Factor
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    ABSTRACT: The active VITATOPS trial medication reduces mean tHcy concentrations by 3,7 micromo VL (95%Cl: 2.7 to 4.7 micromo VL) in the Perth population studied. The treatment effect has not attenuated significantly in the past 5 years with increasing voluntary fortification of foods with folic acid. These data suggest that in the continuing absence of a program of mandatory folate fortification of food in populations served by centers participating in he VITATOPS trial, the study will remain adequately powered to test the homocysteine-lowering hypothesis for which it was designed.
    29th International Stroke Conference, San Diego, California, 5-7 Feb 2004., San Diego, California, USA; 02/2004
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