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> Vitamin B supplements for prevention of stroke, Life is never easy
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post Aug 17, 2010, 11:05 AM
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Vitamin B supplements for prevention of stroke
The Lancet Neurology
Volume 9, Issue 9, September 2010, Pages 842-84
Peter Sandercock, Department of Clinical Neurosciences, Western General Hospital, Edinburgh, UK

Refers to:
B vitamins in patients with recent transient ischaemic attack or stroke in the VITAmins TO Prevent Stroke (VITATOPS) trial: a randomised, double-blind, parallel, placebo-controlled trial
The Lancet Neurology, Volume 9, Issue 9, September 2010, Pages 855-865,
The VITATOPS Trial Study Group

Reflection and Reaction

Every year, about 15 million people worldwide have an acute stroke. If widespread treatment with a simple, inexpensive vitamin pill for a few years among stroke survivors had even a small effect on the risk of subsequent vascular events, the effect on the global burden of vascular disease could be very large. From the perspective of efforts to tackle the ever increasing global burden of non-communicable diseases, the results of the VITAmins TO Prevent Stroke (VITATOPS) trial, published in this issue of The Lancet Neurology,1 are of great interest. The central hypothesis was that, among patients with ischaemic stroke or transient ischaemic attack, lowering blood concentrations of homocysteine with a combination of folic acid, vitamin B6, and vitamin B12 over a few years would give a relative reduction in the risk of vascular events of about 15%. An increased concentration of homocysteine in the blood is a moderate risk factor for stroke and coronary artery disease.2 Although the vitamin combination used in the VITATOPS trial resulted in a reduction in homocysteine (an estimated 2% [95% CI −0·5 to 4·3] reduction in the risk of the primary outcome for each 1 μmol/L decrease in homocysteine), vitamin treatment was not significantly more effective than placebo in reducing the incidence of the composite primary endpoint of stroke, myocardial infarction, or vascular death.

So what—if anything—went wrong? Was the trial underpowered? Rory Collins and Stephen MacMahon3 summarised the problem of trial power succinctly when they wrote: “It is still not sufficiently widely appreciated just how large clinical trials need to be to detect reliably the sort of moderate, but important, differences in major outcomes that might exist.” Even though the VITATOPS trial included over 8000 patients at high risk of recurrent stroke, the estimated effect on the primary outcome was rather imprecise (95% CI 0–18% relative risk reduction) and could not—beyond reasonable doubt—exclude the 15% relative risk reduction the trial was originally powered to detect. The systematic review of relevant trials that reported vascular events included a large amount of data from 35 000 people randomly assigned to B vitamins or placebo.1 The estimated effect on vascular events was precise enough to exclude a 15% relative risk reduction. However, there was weak evidence for an 8% relative risk reduction in fatal or non-fatal stroke (risk ratio 0·92, 95% CI 0·84–1·00); if that is the true effect of the intervention, then B vitamins could still be potentially worthwhile. A large global trial—preferably with a treatment regimen that results in a larger reduction in homocysteine concentrations—with several tens of thousands of patients would be required to confirm or refute such moderate effects. At least one further homocysteine-lowering trial is ongoing at present4 and there are plans for an individual patient data meta-analysis which might—with the additional data—help to resolve some of the uncertainties.5 So, for now, do we conclude that the observational epidemiology was wrong and the trials to date have given the correct answer—that homocysteine lowering with B vitamins is not effective? There are many examples in medicine where accumulation of data from large, sufficiently powered trials, completion of meta-analyses of those trials, and consequent appreciation of the benefits of those treatments has taken a very long time—for example, antiplatelet treatment with aspirin, cholesterol reduction with drugs, and tamoxifen for breast cancer. With that in mind, I think the jury is still out on homocysteine reduction, at least until the present trials are complete.

The VITATOPS trial1 also shows how difficult it is—in the present regulatory environment—to undertake large-scale investigator-led randomised trials of treatments that have no commercial potential. In that context, the VITATOPS trial1 is a remarkable achievement, and the investigators are to be congratulated for obtaining the funding and overcoming innumerable obstacles in completing the trial—very much against the odds. The difficulties faced by the VITATOPS group over the 12 years the trial took send out a worrying signal; they confirm my personal concerns (shared by many) that investigator-led trials of non-commercial interventions face an increasingly uncertain future. There are many such promising interventions for stroke treatment, rehabilitation, and prevention that investigators who are just starting their careers might wish to evaluate in large-scale randomised trials, but which will never attract support from a commercial sponsor (for examples, see6). Faced with overcoming the obstacles to undertake clinical trials, I suspect that these researchers will probably choose the easier options of laboratory research or bedside clinical epidemiology, which at least offer the prospect of a chance to complete their study within a few years.

To conclude, the VITATOPS trial1 does not provide sufficiently robust evidence to support a policy of giving B vitamin supplements for secondary prevention after transient ischaemic attack or minor stroke. However, there is still a place for further trials of homocysteine-lowering treatment, especially if the intervention can achieve and sustain large reductions in homocysteine.

I have no conflicts of interest.

References

1 The VITATOPS Trial Study Group, B vitamins in patients with recent transient ischaemic attack or stroke in the VITAmins TO Prevent Stroke (VITATOPS) trial: a randomised, double-blind, parallel, placebo-controlled trial, Lancet Neurol (2010) 10.1016/S1474-4422(10)70187-3 published online Aug 4..
2 Homocysteine Studies Collaboration, Homocysteine and risk of ischemic heart disease and stroke: a meta-analysis, JAMA 288 (2002), pp. 2015–2022.
3 R Collins and S MacMahon, Reliable assessment of the effects of treatment on mortality and major morbidity, I: clinical trials, Lancet 357 (2001), pp. 373–380. Article | PDF (114 K) | View Record in Scopus | Cited By in Scopus (114)
4 AG Bostom, MA Carpenter, L Hunsicker et al. and for the FAVORIT Study Investigators, Baseline characteristics of participants in the Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) Trial, Am J Kidney Dis 53 (2009), pp. 121–128. Abstract | Article | PDF (282 K) | View Record in Scopus | Cited By in Scopus (3)
5 R Clarke, J Armitage, S Lewington and R Collins, Homocysteine-lowering trials for prevention of vascular disease: protocol for a collaborative meta-analysis, Clin Chem Lab Med 45 (2007), pp. 1575–1581. View Record in Scopus | Cited By in Scopus (11)
6 Cochrane Stroke Group, List of Reviews, Protocols and Titles registered with the Cochrane Stroke Group http://www.dcn.ed.ac.uk/csrg/cliblist.asp (accessed July 25, 2010).
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GodConsciousness
post Aug 17, 2010, 12:08 PM
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Pyritinol and Sulbutiamine (both based on B vitamins) may also be helpful in recovering from stroke (and perhaps even prevention).
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alisha99
post Jul 26, 2012, 12:54 AM
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QUOTE(GodConsciousness @ Aug 17, 2010, 12:08 PM) *

Pyritinol and Sulbutiamine (both based on B vitamins) may also be helpful in recovering from stroke (and perhaps even prevention).


Yes, Pyritinol is helpful in recovering from stroke.
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