title: Differential effect of B-vitamin therapy by antiplatelet use on risk of recurrent vascular events after stroke.
abstract: OBJECTIVE
  Although several randomized controlled trials failed to show a benefit of B vitamin therapy on composite outcomes of cardiovascular death, myocardial infarction, and stroke among individuals with elevated homocysteine, recent post hoc analyses have suggested that several factors may interact with the effects of vitamin treatment. One post hoc analysis revealed an interaction between B vitamin therapy and antiplatelet use; however, those results have not been replicated in other studies or populations.
  
  
  METHODS
  We conducted a post hoc analysis of the Vitamin Intervention for Stroke Prevention (VISP) trial, a randomized controlled trial evaluating treatment with high- versus low-dose B vitamin therapy for secondary prevention of vascular events among stroke survivors with elevated homocysteine. Cox regression models were used to assess primary (recurrent stroke) and secondary (stroke, myocardial infarction, or vascular death) outcomes among individuals on high- versus low-dose vitamin therapy, categorized by antiplatelet use, after adjusting for covariates.
  
  
  RESULTS
  Among 3680 participants, 52% took antiplatelet medications. When compared with low-dose therapy, high-dose vitamin therapy was associated with higher stroke risk among individuals on antiplatelets (hazard ratio, 1.43; 95% confidence interval, 1.02-2.01), but trended toward lower risk among those not on antiplatelets (hazard ratio, 0.86; 95% confidence interval, 0.62-1.19).
  
  
  CONCLUSIONS
  High-dose B vitamin therapy may be associated with a higher risk of recurrent stroke among stroke survivors taking antiplatelets, but does not have a significant effect on recurrent stroke risk in those who are not on antiplatelets. Future randomized controlled trials may consider evaluating the effect of homocysteine lowering among stroke survivors with elevated homocysteine who are not on antiplatelet therapy.
authors: From the Department of Neurology, University of Southern California, Los Angeles (B.A., A.T.); Department of Neurology, Rancho Los Amigos National Rehabilitation Center, Downey, CA (B.A., A.T.); Department of Neurosciences, Medical University of South Carolina, Charleston (B.O.); Department of Biomathematics, University of California, Los Angeles (D.M.); and Department of Neurology, University of Toronto, Toronto, Ontario, Canada (G.S.).
authors: Baback
authors: B
authors: Arshi
authors: From the Department of Neurology, University of Southern California, Los Angeles (B.A., A.T.); Department of Neurology, Rancho Los Amigos National Rehabilitation Center, Downey, CA (B.A., A.T.); Department of Neurosciences, Medical University of South Carolina, Charleston (B.O.); Department of Biomathematics, University of California, Los Angeles (D.M.); and Department of Neurology, University of Toronto, Toronto, Ontario, Canada (G.S.).
authors: Bruce
authors: B
authors: Ovbiagele
authors: From the Department of Neurology, University of Southern California, Los Angeles (B.A., A.T.); Department of Neurology, Rancho Los Amigos National Rehabilitation Center, Downey, CA (B.A., A.T.); Department of Neurosciences, Medical University of South Carolina, Charleston (B.O.); Department of Biomathematics, University of California, Los Angeles (D.M.); and Department of Neurology, University of Toronto, Toronto, Ontario, Canada (G.S.).
authors: Daniela
authors: D
authors: Markovic
authors: From the Department of Neurology, University of Southern California, Los Angeles (B.A., A.T.); Department of Neurology, Rancho Los Amigos National Rehabilitation Center, Downey, CA (B.A., A.T.); Department of Neurosciences, Medical University of South Carolina, Charleston (B.O.); Department of Biomathematics, University of California, Los Angeles (D.M.); and Department of Neurology, University of Toronto, Toronto, Ontario, Canada (G.S.).
authors: Gustavo
authors: G
authors: Saposnik
authors: From the Department of Neurology, University of Southern California, Los Angeles (B.A., A.T.); Department of Neurology, Rancho Los Amigos National Rehabilitation Center, Downey, CA (B.A., A.T.); Department of Neurosciences, Medical University of South Carolina, Charleston (B.O.); Department of Biomathematics, University of California, Los Angeles (D.M.); and Department of Neurology, University of Toronto, Toronto, Ontario, Canada (G.S.). towfighi@usc.edu.
authors: Amytis
authors: A
authors: Towfighi
mesh_terms: D000367:Age Factors; D000368:Aged; D003627:Data Interpretation, Statistical; D004311:Double-Blind Method; D005260:Female; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D016016:Proportional Hazards Models; D012008:Recurrence; D012307:Risk Factors; D020521:Stroke / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology*; D016896:Treatment Outcome; D014803:Vitamin B Complex / Q000627:therapeutic use*
chemical_list: D010975:Platelet Aggregation Inhibitors; D006710:Homocysteine; D014803:Vitamin B Complex
keywords: antiplatelet agents; homocysteine; myocardial infarction; stroke; vitamin B complex